merge 8.6 (TIP#527, New measurement facilities in TCL: New command timerate, performance test suite)

14 files changed, 1777 insertions, 98 deletions

diff --git a/doc/timerate.n b/doc/timerate.n
new file mode 100644
index 0000000..3c764c8
--- /dev/null
+++ b/doc/timerate.n
@@ -0,0 +1,129 @@
+'\"
+'\" Copyright (c) 2005 Sergey Brester aka sebres.
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\"
+.TH timerate n "" Tcl "Tcl Built-In Commands"
+.so man.macros
+.BS
+'\" Note:  do not modify the .SH NAME line immediately below!
+.SH NAME
+timerate \- Time-related execution resp. performance measurement of a script
+.SH SYNOPSIS
+\fBtimerate \fIscript\fR \fI?time ?max-count??\fR
+.sp
+\fBtimerate \fI?-direct?\fR \fI?-overhead double?\fR \fIscript\fR \fI?time ?max-count??\fR
+.sp
+\fBtimerate \fI?-calibrate?\fR \fI?-direct?\fR \fIscript\fR \fI?time ?max-count??\fR
+.BE
+.SH DESCRIPTION
+.PP
+The first and second form will evaluate \fIscript\fR until the interval
+\fItime\fR given in milliseconds elapses, or for 1000 milliseconds (1 second)
+if \fItime\fR is not specified.
+.sp
+The parameter \fImax-count\fR could additionally impose a further restriction
+by the maximal number of iterations to evaluate the script.
+If \fImax-count\fR is specified, the evalution will stop either this count of
+iterations is reached or the time is exceeded.
+.sp
+It will then return a canonical tcl-list of the form
+.PP
+.CS
+\fB0.095977 \(mcs/# 52095836 # 10419167 #/sec 5000.000 nett-ms\fR
+.CE
+.PP
+which indicates:
+.IP \(bu
+the average amount of time required per iteration, in microseconds ([\fBlindex\fR $result 0])
+.IP \(bu
+the count how many times it was executed ([\fBlindex\fR $result 2])
+.IP \(bu
+the estimated rate per second ([\fBlindex\fR $result 4])
+.IP \(bu
+the estimated real execution time without measurement overhead ([\fBlindex\fR $result 6])
+.PP
+Time is measured in elapsed time using the finest timer resolution as possible,
+not CPU time.
+This command may be used to provide information as to how well the script or a
+tcl-command is performing and can help determine bottlenecks and fine-tune
+application performance.
+.TP
+\fI-calibrate\fR
+.
+To measure very fast scripts as exact as posible the calibration process
+may be required.
+
+The \fI-calibrate\fR option is used to calibrate timerate, calculating the
+estimated overhead of the given script as the default overhead for future 
+invocations of the \fBtimerate\fR command. If the \fItime\fR parameter is not 
+specified, the calibrate procedure runs for up to 10 seconds.
+.TP
+\fI-overhead double\fR
+.
+The \fI-overhead\fR parameter supplies an estimate (in microseconds) of the
+measurement overhead of each iteration of the tested script. This quantity
+will be subtracted from the measured time prior to reporting results.
+.TP
+\fI-direct\fR
+.
+The \fI-direct\fR option causes direct execution of the supplied script,
+without compilation, in a manner similar to the \fBtime\fR command. It can be
+used to measure the cost of \fBTcl_EvalObjEx\fR, of the invocation of canonical
+lists, and of the uncompiled versions of bytecoded commands.
+.PP
+As opposed to the \fBtime\fR commmand, which runs the tested script for a fixed
+number of iterations, the timerate command runs it for a fixed time.
+Additionally, the compiled variant of the script will be used during the entire
+measurement, as if the script were part of a compiled procedure, if the \fI-direct\fR
+option is not specified. The fixed time period and possibility of compilation allow
+for more precise results and prevent very long execution times by slow scripts, making
+it practical for measuring scripts with highly uncertain execution times.
+
+.SH EXAMPLE
+Estimate how fast it takes for a simple Tcl \fBfor\fR loop (including
+operations on variable \fIi\fR) to count to a ten:
+.PP
+.CS
+# calibrate:
+timerate -calibrate {}
+# measure:
+timerate { for {set i 0} {$i<10} {incr i} {} } 5000
+.CE
+.PP
+Estimate how fast it takes for a simple Tcl \fBfor\fR loop, ignoring the
+overhead for to perform ten iterations, ignoring the overhead of the management
+of the variable that controls the loop:
+.PP
+.CS
+# calibrate for overhead of variable operations:
+set i 0; timerate -calibrate {expr {$i<10}; incr i} 1000
+# measure:
+timerate { for {set i 0} {$i<10} {incr i} {} } 5000
+.CE
+.PP
+Estimate the speed of calculating the hour of the day using \fBclock format\fR only,
+ignoring overhead of the portion of the script that prepares the time for it to
+calculate:
+.PP
+.CS
+# calibrate:
+timerate -calibrate {}
+# estimate overhead:
+set tm 0
+set ovh [lindex [timerate { incr tm [expr {24*60*60}] }] 0]
+# measure using esimated overhead:
+set tm 0
+timerate -overhead $ovh {
+    clock format $tm -format %H
+    incr tm [expr {24*60*60}]; # overhead for this is ignored
+} 5000
+.CE
+.SH "SEE ALSO"
+time(n)
+.SH KEYWORDS
+script, timerate, time
+.\" Local Variables:
+.\" mode: nroff
+.\" End:
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index 25b6f78..47579a4 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -319,6 +319,9 @@ static const CmdInfo builtInCmds[] = {
     {"source",		Tcl_SourceObjCmd,	NULL,			TclNRSourceObjCmd,	0},
     {"tell",		Tcl_TellObjCmd,		NULL,			NULL,	CMD_IS_SAFE},
     {"time",		Tcl_TimeObjCmd,		NULL,			NULL,	CMD_IS_SAFE},
+#ifdef TCL_TIMERATE
+    {"timerate",	Tcl_TimeRateObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
+#endif
     {"unload",		Tcl_UnloadObjCmd,	NULL,			NULL,	0},
     {"update",		Tcl_UpdateObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
     {"vwait",		Tcl_VwaitObjCmd,	NULL,			NULL,	CMD_IS_SAFE},
@@ -559,7 +562,7 @@ Tcl_CreateInterp(void)
     const BuiltinFuncDef *builtinFuncPtr;
     const OpCmdInfo *opcmdInfoPtr;
     const CmdInfo *cmdInfoPtr;
-    Tcl_Namespace *mathfuncNSPtr, *mathopNSPtr;
+    Tcl_Namespace *nsPtr;
     Tcl_HashEntry *hPtr;
     int isNew;
     CancelInfo *cancelInfo;
@@ -974,6 +977,17 @@ Tcl_CreateInterp(void)
     Tcl_NRCreateCommand(interp, "::tcl::unsupported::inject", NULL,
 	    NRCoroInjectObjCmd, NULL, NULL);
 
+    /* Create an unsupported command for timerate */
+    Tcl_CreateObjCommand(interp, "::tcl::unsupported::timerate",
+	    Tcl_TimeRateObjCmd, NULL, NULL);
+
+    /* Export unsupported commands */
+    nsPtr = Tcl_FindNamespace(interp, "::tcl::unsupported", NULL, 0);
+    if (nsPtr) {
+	Tcl_Export(interp, nsPtr, "*", 1);
+    }
+
+
 #ifdef USE_DTRACE
     /*
      * Register the tcl::dtrace command.
@@ -986,8 +1000,8 @@ Tcl_CreateInterp(void)
      * Register the builtin math functions.
      */
 
-    mathfuncNSPtr = Tcl_CreateNamespace(interp, "::tcl::mathfunc", NULL,NULL);
-    if (mathfuncNSPtr == NULL) {
+    nsPtr = Tcl_CreateNamespace(interp, "::tcl::mathfunc", NULL,NULL);
+    if (nsPtr == NULL) {
 	Tcl_Panic("Can't create math function namespace");
     }
 #define MATH_FUNC_PREFIX_LEN 17 /* == strlen("::tcl::mathfunc::") */
@@ -997,18 +1011,18 @@ Tcl_CreateInterp(void)
 	strcpy(mathFuncName+MATH_FUNC_PREFIX_LEN, builtinFuncPtr->name);
 	Tcl_CreateObjCommand(interp, mathFuncName,
 		builtinFuncPtr->objCmdProc, builtinFuncPtr->clientData, NULL);
-	Tcl_Export(interp, mathfuncNSPtr, builtinFuncPtr->name, 0);
+	Tcl_Export(interp, nsPtr, builtinFuncPtr->name, 0);
     }
 
     /*
      * Register the mathematical "operator" commands. [TIP #174]
      */
 
-    mathopNSPtr = Tcl_CreateNamespace(interp, "::tcl::mathop", NULL, NULL);
-    if (mathopNSPtr == NULL) {
+    nsPtr = Tcl_CreateNamespace(interp, "::tcl::mathop", NULL, NULL);
+    if (nsPtr == NULL) {
 	Tcl_Panic("can't create math operator namespace");
     }
-    Tcl_Export(interp, mathopNSPtr, "*", 1);
+    Tcl_Export(interp, nsPtr, "*", 1);
 #define MATH_OP_PREFIX_LEN 15 /* == strlen("::tcl::mathop::") */
     memcpy(mathFuncName, "::tcl::mathop::", MATH_OP_PREFIX_LEN);
     for (opcmdInfoPtr=mathOpCmds ; opcmdInfoPtr->name!=NULL ; opcmdInfoPtr++){
diff --git a/generic/tclClock.c b/generic/tclClock.c
index 233ddd2..aeff164 100644
--- a/generic/tclClock.c
+++ b/generic/tclClock.c
@@ -1772,8 +1772,7 @@ ClockClicksObjCmd(
 #endif
 	break;
     case CLICKS_MICROS:
-	Tcl_GetTime(&now);
-	clicks = ((Tcl_WideInt) now.sec * 1000000) + now.usec;
+	clicks = TclpGetMicroseconds();
 	break;
     }
 
@@ -1843,15 +1842,11 @@ ClockMicrosecondsObjCmd(
     int objc,			/* Parameter count */
     Tcl_Obj *const *objv)	/* Parameter values */
 {
-    Tcl_Time now;
-
     if (objc != 1) {
 	Tcl_WrongNumArgs(interp, 1, objv, NULL);
 	return TCL_ERROR;
     }
-    Tcl_GetTime(&now);
-    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(
-	    ((Tcl_WideInt) now.sec * 1000000) + now.usec));
+    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(TclpGetMicroseconds()));
     return TCL_OK;
 }
 
diff --git a/generic/tclCmdMZ.c b/generic/tclCmdMZ.c
index bd93205..7349515 100644
--- a/generic/tclCmdMZ.c
+++ b/generic/tclCmdMZ.c
@@ -17,6 +17,7 @@
  */
 
 #include "tclInt.h"
+#include "tclCompile.h"
 #include "tclRegexp.h"
 #include "tclStringTrim.h"
 
@@ -4030,7 +4031,7 @@ Tcl_TimeObjCmd(
     start = TclpGetWideClicks();
 #endif
     while (i-- > 0) {
-	result = Tcl_EvalObjEx(interp, objPtr, 0);
+	result = TclEvalObjEx(interp, objPtr, 0, NULL, 0);
 	if (result != TCL_OK) {
 	    return result;
 	}
@@ -4070,6 +4071,390 @@ Tcl_TimeObjCmd(
 /*
  *----------------------------------------------------------------------
  *
+ * Tcl_TimeRateObjCmd --
+ *
+ *	This object-based procedure is invoked to process the "timerate" Tcl
+ *	command. 
+ *	This is similar to command "time", except the execution limited by 
+ *	given time (in milliseconds) instead of repetition count.
+ *
+ * Example:
+ *	timerate {after 5} 1000 ; # equivalent for `time {after 5} [expr 1000/5]`
+ *
+ * Results:
+ *	A standard Tcl object result.
+ *
+ * Side effects:
+ *	See the user documentation.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+Tcl_TimeRateObjCmd(
+    ClientData dummy,		/* Not used. */
+    Tcl_Interp *interp,		/* Current interpreter. */
+    int objc,			/* Number of arguments. */
+    Tcl_Obj *const objv[])	/* Argument objects. */
+{
+    static 
+    double measureOverhead = 0; /* global measure-overhead */
+    double overhead = -1;	/* given measure-overhead */
+    register Tcl_Obj *objPtr;
+    register int result, i;
+    Tcl_Obj *calibrate = NULL, *direct = NULL;
+    Tcl_WideUInt count = 0;	/* Holds repetition count */
+    Tcl_WideInt  maxms  = WIDE_MIN;
+				/* Maximal running time (in milliseconds) */
+    Tcl_WideUInt maxcnt = WIDE_MAX;
+				/* Maximal count of iterations. */
+    Tcl_WideUInt threshold = 1;	/* Current threshold for check time (faster
+				 * repeat count without time check) */
+    Tcl_WideUInt maxIterTm = 1;	/* Max time of some iteration as max threshold
+				 * additionally avoid divide to zero (never < 1) */
+    unsigned short factor = 50;	/* Factor (4..50) limiting threshold to avoid
+				 * growth of execution time. */
+    register Tcl_WideInt start, middle, stop;
+#ifndef TCL_WIDE_CLICKS
+    Tcl_Time now;
+#endif
+
+    static const char *const options[] = {
+	"-direct",	"-overhead",	"-calibrate",	"--",	NULL
+    };
+    enum options {
+	TMRT_EV_DIRECT,	TMRT_OVERHEAD,	TMRT_CALIBRATE,	TMRT_LAST
+    };
+
+    NRE_callback *rootPtr;
+    ByteCode	 *codePtr = NULL;
+
+    for (i = 1; i < objc - 1; i++) {
+    	int index;
+	if (Tcl_GetIndexFromObj(NULL, objv[i], options, "option", TCL_EXACT,
+		&index) != TCL_OK) {
+	    break;
+	}
+	if (index == TMRT_LAST) {
+	    i++;
+	    break;
+	}
+	switch (index) {
+	case TMRT_EV_DIRECT:
+	    direct = objv[i];
+	    break;
+	case TMRT_OVERHEAD:
+	    if (++i >= objc - 1) {
+		goto usage;
+	    }
+	    if (Tcl_GetDoubleFromObj(interp, objv[i], &overhead) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    break;
+	case TMRT_CALIBRATE:
+	    calibrate = objv[i];
+	    break;
+	}
+    }
+
+    if (i >= objc || i < objc-3) {
+usage:
+	Tcl_WrongNumArgs(interp, 1, objv, "?-direct? ?-calibrate? ?-overhead double? command ?time ?max-count??");
+	return TCL_ERROR;
+    }
+    objPtr = objv[i++];
+    if (i < objc) {	/* max-time */
+	result = Tcl_GetWideIntFromObj(interp, objv[i++], &maxms);
+	if (result != TCL_OK) {
+	    return result;
+	}
+	if (i < objc) {	/* max-count*/
+	    Tcl_WideInt v;
+	    result = Tcl_GetWideIntFromObj(interp, objv[i], &v);
+	    if (result != TCL_OK) {
+		return result;
+	    }
+	    maxcnt = (v > 0) ? v : 0;
+	}
+    }
+
+    /* if calibrate */
+    if (calibrate) {
+
+	/* if no time specified for the calibration */
+	if (maxms == WIDE_MIN) {
+	    Tcl_Obj *clobjv[6];
+	    Tcl_WideInt maxCalTime = 5000;
+	    double lastMeasureOverhead = measureOverhead;
+	    
+	    clobjv[0] = objv[0]; 
+	    i = 1;
+	    if (direct) {
+	    	clobjv[i++] = direct;
+	    }
+	    clobjv[i++] = objPtr; 
+
+	    /* reset last measurement overhead */
+	    measureOverhead = (double)0;
+
+	    /* self-call with 100 milliseconds to warm-up,
+	     * before entering the calibration cycle */
+	    TclNewIntObj(clobjv[i], 100);
+	    Tcl_IncrRefCount(clobjv[i]);
+	    result = Tcl_TimeRateObjCmd(dummy, interp, i+1, clobjv);
+	    Tcl_DecrRefCount(clobjv[i]);
+	    if (result != TCL_OK) {
+		return result;
+	    }
+
+	    i--;
+	    clobjv[i++] = calibrate;
+	    clobjv[i++] = objPtr; 
+
+	    /* set last measurement overhead to max */
+	    measureOverhead = (double)UWIDE_MAX;
+
+	    /* calibration cycle until it'll be preciser */
+	    maxms = -1000;
+	    do {
+		lastMeasureOverhead = measureOverhead;
+		TclNewIntObj(clobjv[i], (int)maxms);
+		Tcl_IncrRefCount(clobjv[i]);
+		result = Tcl_TimeRateObjCmd(dummy, interp, i+1, clobjv);
+		Tcl_DecrRefCount(clobjv[i]);
+		if (result != TCL_OK) {
+		    return result;
+		}
+		maxCalTime += maxms;
+		/* increase maxms for preciser calibration */
+		maxms -= (-maxms / 4);
+		/* as long as new value more as 0.05% better */
+	    } while ( (measureOverhead >= lastMeasureOverhead
+		    || measureOverhead / lastMeasureOverhead <= 0.9995)
+		    && maxCalTime > 0
+	    );
+
+	    return result;
+	}
+	if (maxms == 0) {
+	    /* reset last measurement overhead */
+	    measureOverhead = 0;
+	    Tcl_SetObjResult(interp, Tcl_NewLongObj(0));
+	    return TCL_OK;
+	}
+
+	/* if time is negative - make current overhead more precise */
+	if (maxms > 0) {
+	    /* set last measurement overhead to max */
+	    measureOverhead = (double)UWIDE_MAX;
+	} else {
+	    maxms = -maxms;
+	}
+
+    }
+
+    if (maxms == WIDE_MIN) {
+    	maxms = 1000;
+    }
+    if (overhead == -1) {
+	overhead = measureOverhead;
+    }
+
+    /* be sure that resetting of result will not smudge the further measurement */
+    Tcl_ResetResult(interp);
+
+    /* compile object */
+    if (!direct) {
+	if (TclInterpReady(interp) != TCL_OK) {
+	    return TCL_ERROR;
+	}
+	codePtr = TclCompileObj(interp, objPtr, NULL, 0);
+	TclPreserveByteCode(codePtr);
+    }
+
+    /* get start and stop time */
+#ifdef TCL_WIDE_CLICKS
+    start = middle = TclpGetWideClicks();
+    /* time to stop execution (in wide clicks) */
+    stop = start + (maxms * 1000 / TclpWideClickInMicrosec());
+#else
+    Tcl_GetTime(&now);
+    start = now.sec; start *= 1000000; start += now.usec;
+    middle = start;
+    /* time to stop execution (in microsecs) */
+    stop = start + maxms * 1000;
+#endif
+
+    /* start measurement */
+    if (maxcnt > 0)
+    while (1) {
+    	/* eval single iteration */
+    	count++;
+
+	if (!direct) {
+	    /* precompiled */
+	    rootPtr = TOP_CB(interp);
+	    result = TclNRExecuteByteCode(interp, codePtr);
+	    result = TclNRRunCallbacks(interp, result, rootPtr);
+	} else {
+	    /* eval */
+	    result = TclEvalObjEx(interp, objPtr, 0, NULL, 0);
+	}
+	if (result != TCL_OK) {
+	    /* allow break from measurement cycle (used for conditional stop) */
+	    if (result != TCL_BREAK) {
+		goto done;
+	    }
+	    /* force stop immediately */
+	    threshold = 1;
+	    maxcnt = 0;
+	    result = TCL_OK;
+	}
+	
+	/* don't check time up to threshold */
+	if (--threshold > 0) continue;
+
+	/* check stop time reached, estimate new threshold */
+    #ifdef TCL_WIDE_CLICKS
+	middle = TclpGetWideClicks();
+    #else
+	Tcl_GetTime(&now);
+	middle = now.sec; middle *= 1000000; middle += now.usec;
+    #endif
+	if (middle >= stop || count >= maxcnt) {
+	    break;
+	}
+
+	/* don't calculate threshold by few iterations, because sometimes first
+	 * iteration(s) can be too fast or slow (cached, delayed clean up, etc) */
+	if (count < 10) {
+	   threshold = 1; continue;
+	}
+
+	/* average iteration time in microsecs */
+	threshold = (middle - start) / count;
+	if (threshold > maxIterTm) {
+	    maxIterTm = threshold;
+	    /* interations seems to be longer */
+	    if (threshold > (maxIterTm * 2)) {
+		if ((factor *= 2) > 50) factor = 50;
+	    } else {
+		if (factor < 50) factor++;
+	    }
+	} else if (factor > 4) {
+	    /* interations seems to be shorter */
+	    if (threshold < (maxIterTm / 2)) {
+		if ((factor /= 2) < 4) factor = 4;
+	    } else {
+		factor--;
+	    }
+	}
+	/* as relation between remaining time and time since last check,
+	 * maximal some % of time (by factor), so avoid growing of the execution time
+	 * if iterations are not consistent, e. g. wax continuously on time) */
+	threshold = ((stop - middle) / maxIterTm) / factor + 1;
+	if (threshold > 100000) {	    /* fix for too large threshold */
+	    threshold = 100000;
+	}
+	/* consider max-count */
+	if (threshold > maxcnt - count) {
+	    threshold = maxcnt - count;
+	}
+    }
+
+    {
+	Tcl_Obj *objarr[8], **objs = objarr;
+	Tcl_WideInt val;
+	const char *fmt;
+
+	middle -= start;		     /* execution time in microsecs */
+
+    #ifdef TCL_WIDE_CLICKS
+	/* convert execution time in wide clicks to microsecs */
+	middle *= TclpWideClickInMicrosec();
+    #endif
+
+	/* if not calibrate */
+	if (!calibrate) {
+	    /* minimize influence of measurement overhead */
+	    if (overhead > 0) {
+		/* estimate the time of overhead (microsecs) */
+		Tcl_WideUInt curOverhead = overhead * count;
+		if (middle > (Tcl_WideInt)curOverhead) {
+		    middle -= curOverhead;
+		} else {
+		    middle = 0;
+		}
+	    }
+	} else {
+	    /* calibration - obtaining new measurement overhead */
+	    if (measureOverhead > (double)middle / count) {
+		measureOverhead = (double)middle / count;
+	    }
+	    objs[0] = Tcl_NewDoubleObj(measureOverhead);
+	    TclNewLiteralStringObj(objs[1], "\xC2\xB5s/#-overhead"); /* mics */
+	    objs += 2;
+	}
+
+	val = middle / count;		     /* microsecs per iteration */
+	if (val >= 1000000) {
+	    objs[0] = Tcl_NewWideIntObj(val);
+	} else {
+	    if (val < 10)    { fmt = "%.6f"; } else
+	    if (val < 100)   { fmt = "%.4f"; } else
+	    if (val < 1000)  { fmt = "%.3f"; } else
+	    if (val < 10000) { fmt = "%.2f"; } else
+			     { fmt = "%.1f"; };
+	    objs[0] = Tcl_ObjPrintf(fmt, ((double)middle)/count);
+	}
+
+	objs[2] = Tcl_NewWideIntObj(count); /* iterations */
+	
+	/* calculate speed as rate (count) per sec */
+	if (!middle) middle++; /* +1 ms, just to avoid divide by zero */
+	if (count < (WIDE_MAX / 1000000)) {
+	    val = (count * 1000000) / middle;
+	    if (val < 100000) {
+		if (val < 100)	{ fmt = "%.3f"; } else
+		if (val < 1000) { fmt = "%.2f"; } else
+				{ fmt = "%.1f"; };
+		objs[4] = Tcl_ObjPrintf(fmt, ((double)(count * 1000000)) / middle);
+	    } else {
+		objs[4] = Tcl_NewWideIntObj(val);
+	    }
+	} else {
+	    objs[4] = Tcl_NewWideIntObj((count / middle) * 1000000);
+	}
+
+	/* estimated net execution time (in millisecs) */
+	if (!calibrate) {
+	    objs[6] = Tcl_ObjPrintf("%.3f", (double)middle / 1000);
+	    TclNewLiteralStringObj(objs[7], "nett-ms");
+	}
+
+	/*
+	* Construct the result as a list because many programs have always parsed
+	* as such (extracting the first element, typically).
+	*/
+
+	TclNewLiteralStringObj(objs[1], "\xC2\xB5s/#"); /* mics/# */
+	TclNewLiteralStringObj(objs[3], "#");
+	TclNewLiteralStringObj(objs[5], "#/sec");
+	Tcl_SetObjResult(interp, Tcl_NewListObj(8, objarr));
+    }
+
+done:
+
+    if (codePtr != NULL) {
+	TclReleaseByteCode(codePtr);
+    }
+
+    return result;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * Tcl_TryObjCmd, TclNRTryObjCmd --
  *
  *	This procedure is invoked to process the "try" Tcl command. See the
diff --git a/generic/tclInt.h b/generic/tclInt.h
index 3525bf5..3a77196 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -3259,10 +3259,22 @@ MODULE_SCOPE int	TclpLoadMemory(Tcl_Interp *interp, void *buffer,
 MODULE_SCOPE void	TclInitThreadStorage(void);
 MODULE_SCOPE void	TclFinalizeThreadDataThread(void);
 MODULE_SCOPE void	TclFinalizeThreadStorage(void);
+
 #ifdef TCL_WIDE_CLICKS
 MODULE_SCOPE Tcl_WideInt TclpGetWideClicks(void);
 MODULE_SCOPE double	TclpWideClicksToNanoseconds(Tcl_WideInt clicks);
+MODULE_SCOPE double	TclpWideClickInMicrosec(void);
+#else
+#   ifdef _WIN32
+#	define TCL_WIDE_CLICKS 1
+MODULE_SCOPE Tcl_WideInt TclpGetWideClicks(void);
+MODULE_SCOPE double	TclpWideClickInMicrosec(void);
+#	define		TclpWideClicksToNanoseconds(clicks) \
+				((double)(clicks) * TclpWideClickInMicrosec() * 1000)
+#   endif
 #endif
+MODULE_SCOPE Tcl_WideInt TclpGetMicroseconds(void);
+
 MODULE_SCOPE int	TclZlibInit(Tcl_Interp *interp);
 MODULE_SCOPE void *	TclpThreadCreateKey(void);
 MODULE_SCOPE void	TclpThreadDeleteKey(void *keyPtr);
@@ -3538,6 +3550,9 @@ MODULE_SCOPE int	Tcl_ThrowObjCmd(ClientData dummy, Tcl_Interp *interp,
 MODULE_SCOPE int	Tcl_TimeObjCmd(ClientData clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
+MODULE_SCOPE int	Tcl_TimeRateObjCmd(ClientData clientData,
+			    Tcl_Interp *interp, int objc,
+			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	Tcl_TraceObjCmd(ClientData clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
diff --git a/generic/tclPort.h b/generic/tclPort.h
index d3f6233..58e1f5e 100644
--- a/generic/tclPort.h
+++ b/generic/tclPort.h
@@ -27,5 +27,8 @@
 #define UWIDE_MAX ((Tcl_WideUInt)-1)
 #define WIDE_MAX ((Tcl_WideInt)(UWIDE_MAX >> 1))
 #define WIDE_MIN ((Tcl_WideInt)((Tcl_WideUInt)WIDE_MAX+1))
+#define UWIDE_MAX ((Tcl_WideUInt)-1)
+#define WIDE_MAX ((Tcl_WideInt)(UWIDE_MAX >> 1))
+#define WIDE_MIN ((Tcl_WideInt)((Tcl_WideUInt)WIDE_MAX+1))
 
 #endif /* _TCLPORT */
diff --git a/library/tclIndex b/library/tclIndex
index 87a2814..5a702ad 100644
--- a/library/tclIndex
+++ b/library/tclIndex
@@ -73,3 +73,6 @@ set auto_index(::tcl::tm::Defaults) [list ::tcl::Pkg::source [file join $dir tm.
 set auto_index(::tcl::tm::UnknownHandler) [list ::tcl::Pkg::source [file join $dir tm.tcl]]
 set auto_index(::tcl::tm::roots) [list ::tcl::Pkg::source [file join $dir tm.tcl]]
 set auto_index(::tcl::tm::path) [list ::tcl::Pkg::source [file join $dir tm.tcl]]
+if {[namespace exists ::tcl::unsupported]} {
+    set auto_index(timerate) {namespace import ::tcl::unsupported::timerate}
+}
diff --git a/tests-perf/clock.perf.tcl b/tests-perf/clock.perf.tcl
new file mode 100644
index 0000000..d574c2c
--- /dev/null
+++ b/tests-perf/clock.perf.tcl
@@ -0,0 +1,411 @@
+#!/usr/bin/tclsh
+# ------------------------------------------------------------------------
+#
+# test-performance.tcl --
+# 
+#  This file provides common performance tests for comparison of tcl-speed
+#  degradation by switching between branches.
+#  (currently for clock ensemble only)
+#
+# ------------------------------------------------------------------------
+# 
+# Copyright (c) 2014 Serg G. Brester (aka sebres)
+# 
+# See the file "license.terms" for information on usage and redistribution
+# of this file.
+# 
+
+array set in {-time 500}
+if {[info exists ::argv0] && [file tail $::argv0] eq [file tail [info script]]} {
+  array set in $argv
+}
+
+## common test performance framework:
+if {![namespace exists ::tclTestPerf]} {
+  source [file join [file dirname [info script]] test-performance.tcl]
+}
+
+namespace eval ::tclTestPerf-TclClock {
+
+namespace path {::tclTestPerf}
+
+## set testing defaults:
+set ::env(TCL_TZ) :CET
+
+# warm-up interpeter compiler env, clock platform-related features:
+
+## warm-up test-related features (load clock.tcl, system zones, locales, etc.):
+clock scan "" -gmt 1
+clock scan ""
+clock scan "" -timezone :CET
+clock scan "" -format "" -locale en
+clock scan "" -format "" -locale de
+
+## ------------------------------------------
+
+proc test-format {{reptime 1000}} {
+  _test_run $reptime {
+    # Format : short, week only (in gmt)
+    {clock format 1482525936 -format "%u" -gmt 1}
+    # Format : short, week only (system zone)
+    {clock format 1482525936 -format "%u"}
+    # Format : short, week only (CEST)
+    {clock format 1482525936 -format "%u" -timezone :CET}
+    # Format : date only (in gmt)
+    {clock format 1482525936 -format "%Y-%m-%d" -gmt 1}
+    # Format : date only (system zone)
+    {clock format 1482525936 -format "%Y-%m-%d"}
+    # Format : date only (CEST)
+    {clock format 1482525936 -format "%Y-%m-%d" -timezone :CET}
+    # Format : time only (in gmt)
+    {clock format 1482525936 -format "%H:%M" -gmt 1}
+    # Format : time only (system zone)
+    {clock format 1482525936 -format "%H:%M"}
+    # Format : time only (CEST)
+    {clock format 1482525936 -format "%H:%M" -timezone :CET}
+    # Format : time only (in gmt)
+    {clock format 1482525936 -format "%H:%M:%S" -gmt 1}
+    # Format : time only (system zone)
+    {clock format 1482525936 -format "%H:%M:%S"}
+    # Format : time only (CEST)
+    {clock format 1482525936 -format "%H:%M:%S" -timezone :CET}
+    # Format : default (in gmt)
+    {clock format 1482525936 -gmt 1 -locale en}
+    # Format : default (system zone)
+    {clock format 1482525936 -locale en}
+    # Format : default (CEST)
+    {clock format 1482525936 -timezone :CET -locale en}
+    # Format : ISO date-time (in gmt, numeric zone)
+    {clock format 1246379400 -format "%Y-%m-%dT%H:%M:%S %z" -gmt 1}
+    # Format : ISO date-time (system zone, CEST, numeric zone)
+    {clock format 1246379400 -format "%Y-%m-%dT%H:%M:%S %z"}
+    # Format : ISO date-time (CEST, numeric zone)
+    {clock format 1246379400 -format "%Y-%m-%dT%H:%M:%S %z" -timezone :CET}
+    # Format : ISO date-time (system zone, CEST)
+    {clock format 1246379400 -format "%Y-%m-%dT%H:%M:%S %Z"}
+    # Format : julian day with time (in gmt):
+    {clock format 1246379415 -format "%J %H:%M:%S" -gmt 1}
+    # Format : julian day with time (system zone):
+    {clock format 1246379415 -format "%J %H:%M:%S"}
+
+    # Format : locale date-time (en):
+    {clock format 1246379415 -format "%x %X" -locale en}
+    # Format : locale date-time (de):
+    {clock format 1246379415 -format "%x %X" -locale de}
+
+    # Format : locale lookup table month:
+    {clock format 1246379400 -format "%b" -locale en -gmt 1}
+    # Format : locale lookup 2 tables - month and day:
+    {clock format 1246379400 -format "%b %Od" -locale en -gmt 1}
+    # Format : locale lookup 3 tables - week, month and day:
+    {clock format 1246379400 -format "%a %b %Od" -locale en -gmt 1}
+    # Format : locale lookup 4 tables - week, month, day and year:
+    {clock format 1246379400 -format "%a %b %Od %Oy" -locale en -gmt 1}
+
+    # Format : dynamic clock value (without converter caches):
+    setup {set i 0}
+    {clock format [incr i] -format "%Y-%m-%dT%H:%M:%S" -locale en -timezone :CET}
+    cleanup {puts [clock format $i -format "%Y-%m-%dT%H:%M:%S" -locale en -timezone :CET]}
+    # Format : dynamic clock value (without any converter caches, zone range overflow):
+    setup {set i 0}
+    {clock format [incr i 86400] -format "%Y-%m-%dT%H:%M:%S" -locale en -timezone :CET}
+    cleanup {puts [clock format $i -format "%Y-%m-%dT%H:%M:%S" -locale en -timezone :CET]}
+
+    # Format : dynamic format (cacheable)
+    {clock format 1246379415 -format [string trim "%d.%m.%Y %H:%M:%S "] -gmt 1}
+
+    # Format : all (in gmt, locale en)
+    {clock format 1482525936 -format "%%a = %a | %%A = %A | %%b = %b | %%h = %h | %%B = %B | %%C = %C | %%d = %d | %%e = %e | %%g = %g | %%G = %G | %%H = %H | %%I = %I | %%j = %j | %%J = %J | %%k = %k | %%l = %l | %%m = %m | %%M = %M | %%N = %N | %%p = %p | %%P = %P | %%Q = %Q | %%s = %s | %%S = %S | %%t = %t | %%u = %u | %%U = %U | %%V = %V | %%w = %w | %%W = %W | %%y = %y | %%Y = %Y | %%z = %z | %%Z = %Z | %%n = %n | %%EE = %EE | %%EC = %EC | %%Ey = %Ey | %%n = %n | %%Od = %Od | %%Oe = %Oe | %%OH = %OH | %%Ok = %Ok | %%OI = %OI | %%Ol = %Ol | %%Om = %Om | %%OM = %OM | %%OS = %OS | %%Ou = %Ou | %%Ow = %Ow | %%Oy = %Oy" -gmt 1 -locale en}
+    # Format : all (in CET, locale de)
+    {clock format 1482525936 -format "%%a = %a | %%A = %A | %%b = %b | %%h = %h | %%B = %B | %%C = %C | %%d = %d | %%e = %e | %%g = %g | %%G = %G | %%H = %H | %%I = %I | %%j = %j | %%J = %J | %%k = %k | %%l = %l | %%m = %m | %%M = %M | %%N = %N | %%p = %p | %%P = %P | %%Q = %Q | %%s = %s | %%S = %S | %%t = %t | %%u = %u | %%U = %U | %%V = %V | %%w = %w | %%W = %W | %%y = %y | %%Y = %Y | %%z = %z | %%Z = %Z | %%n = %n | %%EE = %EE | %%EC = %EC | %%Ey = %Ey | %%n = %n | %%Od = %Od | %%Oe = %Oe | %%OH = %OH | %%Ok = %Ok | %%OI = %OI | %%Ol = %Ol | %%Om = %Om | %%OM = %OM | %%OS = %OS | %%Ou = %Ou | %%Ow = %Ow | %%Oy = %Oy" -timezone :CET -locale de}
+  }
+}
+
+proc test-scan {{reptime 1000}} {
+  _test_run $reptime {
+    # Scan : date (in gmt)
+    {clock scan "25.11.2015" -format "%d.%m.%Y" -base 0 -gmt 1}
+    # Scan : date (system time zone, with base)
+    {clock scan "25.11.2015" -format "%d.%m.%Y" -base 0}
+    # Scan : date (system time zone, without base)
+    {clock scan "25.11.2015" -format "%d.%m.%Y"}
+    # Scan : greedy match
+    {clock scan "111" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "1111" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "11111" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "111111" -format "%d%m%y" -base 0 -gmt 1}
+    # Scan : greedy match (space separated)
+    {clock scan "1 1 1" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "111 1" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "1 111" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "1 11 1" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "1 11 11" -format "%d%m%y" -base 0 -gmt 1}
+    {clock scan "11 11 11" -format "%d%m%y" -base 0 -gmt 1}
+
+    # Scan : time (in gmt)
+    {clock scan "10:35:55" -format "%H:%M:%S" -base 1000000000 -gmt 1}
+    # Scan : time (system time zone, with base)
+    {clock scan "10:35:55" -format "%H:%M:%S" -base 1000000000}
+    # Scan : time (gmt, without base)
+    {clock scan "10:35:55" -format "%H:%M:%S" -gmt 1}
+    # Scan : time (system time zone, without base)
+    {clock scan "10:35:55" -format "%H:%M:%S"}
+
+    # Scan : date-time (in gmt)
+    {clock scan "25.11.2015 10:35:55" -format "%d.%m.%Y %H:%M:%S" -base 0 -gmt 1}
+    # Scan : date-time (system time zone with base)
+    {clock scan "25.11.2015 10:35:55" -format "%d.%m.%Y %H:%M:%S" -base 0}
+    # Scan : date-time (system time zone without base)
+    {clock scan "25.11.2015 10:35:55" -format "%d.%m.%Y %H:%M:%S"}
+
+    # Scan : julian day in gmt
+    {clock scan 2451545 -format %J -gmt 1}
+    # Scan : julian day in system TZ
+    {clock scan 2451545 -format %J}
+    # Scan : julian day in other TZ
+    {clock scan 2451545 -format %J -timezone +0200}
+    # Scan : julian day with time:
+    {clock scan "2451545 10:20:30" -format "%J %H:%M:%S"}
+    # Scan : julian day with time (greedy match):
+    {clock scan "2451545 102030" -format "%J%H%M%S"}
+
+    # Scan : century, lookup table month
+    {clock scan {1970 Jan 2} -format {%C%y %b %d} -locale en -gmt 1}
+    # Scan : century, lookup table month and day (both entries are first)
+    {clock scan {1970 Jan 01} -format {%C%y %b %Od} -locale en -gmt 1}
+    # Scan : century, lookup table month and day (list scan: entries with position 12 / 31)
+    {clock scan {2016 Dec 31} -format {%C%y %b %Od} -locale en -gmt 1}
+
+    # Scan : ISO date-time (CEST)
+    {clock scan "2009-06-30T18:30:00+02:00" -format "%Y-%m-%dT%H:%M:%S%z"}
+    {clock scan "2009-06-30T18:30:00 CEST" -format "%Y-%m-%dT%H:%M:%S %z"}
+    # Scan : ISO date-time (UTC)
+    {clock scan "2009-06-30T18:30:00Z" -format "%Y-%m-%dT%H:%M:%S%z"}
+    {clock scan "2009-06-30T18:30:00 UTC" -format "%Y-%m-%dT%H:%M:%S %z"}
+
+    # Scan : locale date-time (en):
+    {clock scan "06/30/2009 18:30:15" -format "%x %X" -gmt 1 -locale en}
+    # Scan : locale date-time (de):
+    {clock scan "30.06.2009 18:30:15" -format "%x %X" -gmt 1 -locale de}
+
+    # Scan : dynamic format (cacheable)
+    {clock scan "25.11.2015 10:35:55" -format [string trim "%d.%m.%Y %H:%M:%S "] -base 0 -gmt 1}
+
+    break
+    # # Scan : long format test (allock chain)
+    # {clock scan "25.11.2015" -format "%d.%m.%Y %d.%m.%Y %d.%m.%Y %d.%m.%Y %d.%m.%Y %d.%m.%Y %d.%m.%Y %d.%m.%Y" -base 0 -gmt 1}
+    # # Scan : dynamic, very long format test (create obj representation, allock chain, GC, etc):
+    # {clock scan "25.11.2015" -format [string repeat "[incr i] %d.%m.%Y %d.%m.%Y" 10] -base 0 -gmt 1}
+    # # Scan : again:
+    # {clock scan "25.11.2015" -format [string repeat "[incr i -1] %d.%m.%Y %d.%m.%Y" 10] -base 0 -gmt 1}
+  } {puts [clock format $_(r) -locale en]}
+}
+
+proc test-freescan {{reptime 1000}} {
+  _test_run $reptime {
+    # FreeScan : relative date
+    {clock scan "5 years 18 months 385 days" -base 0 -gmt 1}
+    # FreeScan : relative date with relative weekday
+    {clock scan "5 years 18 months 385 days Fri" -base 0 -gmt 1}
+    # FreeScan : relative date with ordinal month
+    {clock scan "5 years 18 months 385 days next 1 January" -base 0 -gmt 1}
+    # FreeScan : relative date with ordinal month and relative weekday
+    {clock scan "5 years 18 months 385 days next January Fri" -base 0 -gmt 1}
+    # FreeScan : ordinal month
+    {clock scan "next January" -base 0 -gmt 1}
+    # FreeScan : relative week
+    {clock scan "next Fri" -base 0 -gmt 1}
+    # FreeScan : relative weekday and week offset 
+    {clock scan "next January + 2 week" -base 0 -gmt 1}
+    # FreeScan : time only with base
+    {clock scan "19:18:30" -base 148863600 -gmt 1}
+    # FreeScan : time only without base, gmt
+    {clock scan "19:18:30" -gmt 1}
+    # FreeScan : time only without base, system
+    {clock scan "19:18:30"}
+    # FreeScan : date, system time zone
+    {clock scan "05/08/2016 20:18:30"}
+    # FreeScan : date, supplied time zone
+    {clock scan "05/08/2016 20:18:30" -timezone :CET}
+    # FreeScan : date, supplied gmt (equivalent -timezone :GMT)
+    {clock scan "05/08/2016 20:18:30" -gmt 1}
+    # FreeScan : date, supplied time zone gmt
+    {clock scan "05/08/2016 20:18:30" -timezone :GMT}
+    # FreeScan : time only, numeric zone in string, base time gmt (exchange zones between gmt / -0500)
+    {clock scan "20:18:30 -0500" -base 148863600 -gmt 1}
+    # FreeScan : time only, zone in string (exchange zones between system / gmt)
+    {clock scan "19:18:30 GMT" -base 148863600}
+    # FreeScan : fast switch of zones in cycle - GMT, MST, CET (system) and EST
+    {clock scan "19:18:30 MST" -base 148863600 -gmt 1
+     clock scan "19:18:30 EST" -base 148863600
+    }
+  } {puts [clock format $_(r) -locale en]}
+}
+
+proc test-add {{reptime 1000}} {
+  set tests {
+    # Add : years
+    {clock add 1246379415 5 years -gmt 1}
+    # Add : months
+    {clock add 1246379415 18 months -gmt 1}
+    # Add : weeks
+    {clock add 1246379415 20 weeks -gmt 1}
+    # Add : days
+    {clock add 1246379415 385 days -gmt 1}
+    # Add : weekdays
+    {clock add 1246379415 3 weekdays -gmt 1}
+
+    # Add : hours
+    {clock add 1246379415 5 hours -gmt 1}
+    # Add : minutes
+    {clock add 1246379415 55 minutes -gmt 1}
+    # Add : seconds
+    {clock add 1246379415 100 seconds -gmt 1}
+
+    # Add : +/- in gmt
+    {clock add 1246379415 -5 years +21 months -20 weeks +386 days -19 hours +30 minutes -10 seconds -gmt 1}
+    # Add : +/- in system timezone
+    {clock add 1246379415 -5 years +21 months -20 weeks +386 days -19 hours +30 minutes -10 seconds -timezone :CET}
+
+    # Add : gmt
+    {clock add 1246379415 -5 years 18 months 366 days 5 hours 30 minutes 10 seconds -gmt 1}
+    # Add : system timezone
+    {clock add 1246379415 -5 years 18 months 366 days 5 hours 30 minutes 10 seconds -timezone :CET}
+
+    # Add : all in gmt
+    {clock add 1246379415 4 years 18 months 50 weeks 378 days 3 weekdays 5 hours 30 minutes 10 seconds -gmt 1}
+    # Add : all in system timezone
+    {clock add 1246379415 4 years 18 months 50 weeks 378 days 3 weekdays 5 hours 30 minutes 10 seconds -timezone :CET}
+
+  }
+  # if does not support add of weekdays:
+  if {[catch {clock add 0 3 weekdays -gmt 1}]} {
+    regsub -all {\mweekdays\M} $tests "days" tests
+  }
+  _test_run $reptime $tests {puts [clock format $_(r) -locale en]}
+}
+
+proc test-convert {{reptime 1000}} {
+  _test_run $reptime {
+    # Convert locale (en -> de):
+    {clock format [clock scan "Tue May 30 2017" -format "%a %b %d %Y" -gmt 1 -locale en] -format "%a %b %d %Y" -gmt 1 -locale de}
+    # Convert locale (de -> en):
+    {clock format [clock scan "Di Mai 30 2017" -format "%a %b %d %Y" -gmt 1 -locale de] -format "%a %b %d %Y" -gmt 1 -locale en}
+
+    # Convert TZ: direct
+    {clock format [clock scan "19:18:30" -base 148863600 -timezone EST] -timezone MST}
+    {clock format [clock scan "19:18:30" -base 148863600 -timezone MST] -timezone EST}
+    # Convert TZ: included in scan string & format
+    {clock format [clock scan "19:18:30 EST" -base 148863600] -format "%H:%M:%S %z" -timezone MST}
+    {clock format [clock scan "19:18:30 EST" -base 148863600] -format "%H:%M:%S %z" -timezone EST}
+
+    # Format locale 1x: comparison values
+    {clock format 0 -gmt 1 -locale en} 
+    {clock format 0 -gmt 1 -locale de}
+    {clock format 0 -gmt 1 -locale fr}
+    # Format locale 2x: without switching locale (en, en)
+    {clock format 0 -gmt 1 -locale en; clock format 0 -gmt 1 -locale en}
+    # Format locale 2x: with switching locale (en, de)
+    {clock format 0 -gmt 1 -locale en; clock format 0 -gmt 1 -locale de}
+    # Format locale 3x: without switching locale (en, en, en)
+    {clock format 0 -gmt 1 -locale en; clock format 0 -gmt 1 -locale en; clock format 0 -gmt 1 -locale en}
+    # Format locale 3x: with switching locale (en, de, fr)
+    {clock format 0 -gmt 1 -locale en; clock format 0 -gmt 1 -locale de; clock format 0 -gmt 1 -locale fr}
+
+    # Scan locale 2x: without switching locale (en, en) + (de, de)
+    {clock scan "Tue May 30 2017" -format "%a %b %d %Y" -gmt 1 -locale en; clock scan "Tue May 30 2017" -format "%a %b %d %Y" -gmt 1 -locale en}
+    {clock scan "Di Mai 30 2017" -format "%a %b %d %Y" -gmt 1 -locale de; clock scan "Di Mai 30 2017" -format "%a %b %d %Y" -gmt 1 -locale de}
+    # Scan locale 2x: with switching locale (en, de)
+    {clock scan "Tue May 30 2017" -format "%a %b %d %Y" -gmt 1 -locale en; clock scan "Di Mai 30 2017" -format "%a %b %d %Y" -gmt 1 -locale de}
+    # Scan locale 3x: with switching locale (en, de, fr)
+    {clock scan "Tue May 30 2017" -format "%a %b %d %Y" -gmt 1 -locale en; clock scan "Di Mai 30 2017" -format "%a %b %d %Y" -gmt 1 -locale de; clock scan "mar. mai 30 2017" -format "%a %b %d %Y" -gmt 1 -locale fr}
+
+    # Format TZ 2x: comparison values
+    {clock format 0 -timezone CET -format "%Y-%m-%d %H:%M:%S %z"}
+    {clock format 0 -timezone EST -format "%Y-%m-%d %H:%M:%S %z"}
+    # Format TZ 2x: without switching
+    {clock format 0 -timezone CET -format "%Y-%m-%d %H:%M:%S %z"; clock format 0 -timezone CET -format "%Y-%m-%d %H:%M:%S %z"}
+    {clock format 0 -timezone EST -format "%Y-%m-%d %H:%M:%S %z"; clock format 0 -timezone EST -format "%Y-%m-%d %H:%M:%S %z"}
+    # Format TZ 2x: with switching
+    {clock format 0 -timezone CET -format "%Y-%m-%d %H:%M:%S %z"; clock format 0 -timezone EST -format "%Y-%m-%d %H:%M:%S %z"}
+    # Format TZ 3x: with switching (CET, EST, MST)
+    {clock format 0 -timezone CET -format "%Y-%m-%d %H:%M:%S %z"; clock format 0 -timezone EST -format "%Y-%m-%d %H:%M:%S %z"; clock format 0 -timezone MST -format "%Y-%m-%d %H:%M:%S %z"}
+    # Format TZ 3x: with switching (GMT, EST, MST)
+    {clock format 0 -gmt 1 -format "%Y-%m-%d %H:%M:%S %z"; clock format 0 -timezone EST -format "%Y-%m-%d %H:%M:%S %z"; clock format 0 -timezone MST -format "%Y-%m-%d %H:%M:%S %z"}
+
+    # FreeScan TZ 2x (+1 system-default): without switching TZ
+    {clock scan "19:18:30 MST" -base 148863600; clock scan "19:18:30 MST" -base 148863600}
+    {clock scan "19:18:30 EST" -base 148863600; clock scan "19:18:30 EST" -base 148863600}
+    # FreeScan TZ 2x (+1 system-default): with switching TZ
+    {clock scan "19:18:30 MST" -base 148863600; clock scan "19:18:30 EST" -base 148863600}
+    # FreeScan TZ 2x (+1 gmt, +1 system-default)
+    {clock scan "19:18:30 MST" -base 148863600 -gmt 1; clock scan "19:18:30 EST" -base 148863600}
+    
+    # Scan TZ: comparison included in scan string vs. given
+    {clock scan "2009-06-30T18:30:00 CEST" -format "%Y-%m-%dT%H:%M:%S %z"}
+    {clock scan "2009-06-30T18:30:00 CET" -format "%Y-%m-%dT%H:%M:%S %z"}
+    {clock scan "2009-06-30T18:30:00" -timezone CET -format "%Y-%m-%dT%H:%M:%S"}
+  }
+}
+
+proc test-other {{reptime 1000}} {
+  _test_run $reptime {
+    # Bad zone
+    {catch {clock scan "1 day" -timezone BAD_ZONE -locale en}}
+
+    # Scan : julian day (overflow)
+    {catch {clock scan 5373485 -format %J}}
+
+    # Scan : test rotate of GC objects (format is dynamic, so tcl-obj removed with last reference)
+    {set i 0; time { clock scan "[incr i] - 25.11.2015" -format "$i - %d.%m.%Y" -base 0 -gmt 1 } 50}
+    # Scan : test reusability of GC objects (format is dynamic, so tcl-obj removed with last reference)
+    {set i 50; time { clock scan "[incr i -1] - 25.11.2015" -format "$i - %d.%m.%Y" -base 0 -gmt 1 } 50}
+  }
+}
+
+proc test-ensemble-perf {{reptime 1000}} {
+  _test_run $reptime {
+    # Clock clicks (ensemble)
+    {clock clicks}
+    # Clock clicks (direct)
+    {::tcl::clock::clicks}
+    # Clock seconds (ensemble)
+    {clock seconds}
+    # Clock seconds (direct)
+    {::tcl::clock::seconds}
+    # Clock microseconds (ensemble)
+    {clock microseconds}
+    # Clock microseconds (direct)
+    {::tcl::clock::microseconds}
+    # Clock scan (ensemble)
+    {clock scan ""}
+    # Clock scan (direct)
+    {::tcl::clock::scan ""}
+    # Clock format (ensemble)
+    {clock format 0 -f %s}
+    # Clock format (direct)
+    {::tcl::clock::format 0 -f %s}
+  }
+}
+
+proc test {{reptime 1000}} {
+  puts ""
+  test-ensemble-perf [expr {$reptime / 2}]; #fast enough
+  test-format $reptime
+  test-scan $reptime
+  test-freescan $reptime
+  test-add $reptime
+  test-convert [expr {$reptime / 2}]; #fast enough
+  test-other $reptime
+
+  puts \n**OK**
+}
+
+}; # end of ::tclTestPerf-TclClock
+
+# ------------------------------------------------------------------------
+
+# if calling direct:
+if {[info exists ::argv0] && [file tail $::argv0] eq [file tail [info script]]} {
+  ::tclTestPerf-TclClock::test $in(-time)
+}
diff --git a/tests-perf/test-performance.tcl b/tests-perf/test-performance.tcl
new file mode 100644
index 0000000..4629cd4
--- /dev/null
+++ b/tests-perf/test-performance.tcl
@@ -0,0 +1,144 @@
+# ------------------------------------------------------------------------
+#
+# test-performance.tcl --
+# 
+#  This file provides common performance tests for comparison of tcl-speed
+#  degradation or regression by switching between branches.
+#
+#  To execute test case evaluate direct corresponding file "tests-perf\*.perf.tcl".
+#
+# ------------------------------------------------------------------------
+# 
+# Copyright (c) 2014 Serg G. Brester (aka sebres)
+# 
+# See the file "license.terms" for information on usage and redistribution
+# of this file.
+# 
+
+namespace eval ::tclTestPerf {
+# warm-up interpeter compiler env, calibrate timerate measurement functionality:
+
+# if no timerate here - import from unsupported:
+if {[namespace which -command timerate] eq {}} {
+  namespace inscope ::tcl::unsupported {namespace export timerate}
+  namespace import ::tcl::unsupported::timerate
+}
+
+# if not yet calibrated:
+if {[lindex [timerate {} 10] 6] >= (10-1)} {
+  puts -nonewline "Calibration ... "; flush stdout
+  puts "done: [lrange \
+    [timerate -calibrate {}] \
+  0 1]"
+}
+
+proc {**STOP**} {args} {
+  return -code error -level 4 "**STOP** in [info level [expr {[info level]-2}]] [join $args { }]" 
+}
+
+proc _test_get_commands {lst} {
+  regsub -all {(?:^|\n)[ \t]*(\#[^\n]*|\msetup\M[^\n]*|\mcleanup\M[^\n]*)(?=\n\s*(?:[\{\#]|setup|cleanup|$))} $lst "\n{\\1}"
+}
+
+proc _test_out_total {} {
+  upvar _ _
+
+  set tcnt [llength $_(itm)]
+  if {!$tcnt} {
+    puts ""
+    return
+  }
+
+  set mintm 0x7fffffff
+  set maxtm 0
+  set nett 0
+  set wtm 0
+  set wcnt 0
+  set i 0
+  foreach tm $_(itm) {
+    if {[llength $tm] > 6} {
+      set nett [expr {$nett + [lindex $tm 6]}]
+    }
+    set wtm [expr {$wtm + [lindex $tm 0]}]
+    set wcnt [expr {$wcnt + [lindex $tm 2]}]
+    set tm [lindex $tm 0]
+    if {$tm > $maxtm} {set maxtm $tm; set maxi $i}
+    if {$tm < $mintm} {set mintm $tm; set mini $i}
+    incr i
+  }
+
+  puts [string repeat ** 40]
+  set s [format "%d cases in %.2f sec." $tcnt [expr {([clock milliseconds] - $_(starttime)) / 1000.0}]]
+  if {$nett > 0} {
+    append s [format " (%.2f nett-sec.)" [expr {$nett / 1000.0}]]
+  }
+  puts "Total $s:"
+  lset _(m) 0 [format %.6f $wtm]
+  lset _(m) 2 $wcnt
+  lset _(m) 4 [format %.3f [expr {$wcnt / (($nett ? $nett : ($tcnt * [lindex $_(reptime) 0])) / 1000.0)}]]
+  if {[llength $_(m)] > 6} {
+    lset _(m) 6 [format %.3f $nett]
+  }
+  puts $_(m)
+  puts "Average:"
+  lset _(m) 0 [format %.6f [expr {[lindex $_(m) 0] / $tcnt}]]
+  lset _(m) 2 [expr {[lindex $_(m) 2] / $tcnt}]
+  if {[llength $_(m)] > 6} {
+    lset _(m) 6 [format %.3f [expr {[lindex $_(m) 6] / $tcnt}]]
+    lset _(m) 4 [format %.0f [expr {[lindex $_(m) 2] / [lindex $_(m) 6] * 1000}]]
+  }
+  puts $_(m)
+  puts "Min:"
+  puts [lindex $_(itm) $mini]
+  puts "Max:"
+  puts [lindex $_(itm) $maxi]
+  puts [string repeat ** 40]
+  puts ""
+}
+
+proc _test_run {args} {
+  upvar _ _
+  # parse args:
+  set _(out-result) 1
+  if {[lindex $args 0] eq "-no-result"} {
+    set _(out-result) 0
+    set args [lrange $args 1 end]
+  }
+  if {[llength $args] < 2 || [llength $args] > 3} {
+    return -code error "wrong # args: should be \"[lindex [info level [info level]] 0] ?-no-result? reptime lst ?outcmd?\""
+  }
+  set outcmd {puts $_(r)}
+  set args [lassign $args reptime lst]
+  if {[llength $args]} {
+    set outcmd [lindex $args 0]
+  }
+  # avoid output if only once:
+  if {[lindex $reptime 0] <= 1 || ([llength $reptime] > 1 && [lindex $reptime 1] == 1)} {
+    set _(out-result) 0
+  }
+  array set _ [list itm {} reptime $reptime starttime [clock milliseconds]]
+
+  # process measurement:
+  foreach _(c) [_test_get_commands $lst] {
+    puts "% [regsub -all {\n[ \t]*} $_(c) {; }]"
+    if {[regexp {^\s*\#} $_(c)]} continue
+    if {[regexp {^\s*(?:setup|cleanup)\s+} $_(c)]} {
+      puts [if 1 [lindex $_(c) 1]]
+      continue
+    }
+    # if output result (and not once):
+    if {$_(out-result)} {
+      set _(r) [if 1 $_(c)]
+      if {$outcmd ne {}} $outcmd
+      if {[llength $_(reptime)] > 1} { # decrement max-count
+        lset _(reptime) 1 [expr {[lindex $_(reptime) 1] - 1}]
+      }
+    }
+    puts [set _(m) [timerate $_(c) {*}$_(reptime)]]
+    lappend _(itm) $_(m)
+    puts ""
+  }
+  _test_out_total
+}
+
+}; # end of namespace ::tclTestPerf
diff --git a/tests-perf/timer-event.perf.tcl b/tests-perf/timer-event.perf.tcl
new file mode 100644
index 0000000..805f0f8
--- /dev/null
+++ b/tests-perf/timer-event.perf.tcl
@@ -0,0 +1,182 @@
+#!/usr/bin/tclsh
+
+# ------------------------------------------------------------------------
+#
+# timer-event.perf.tcl --
+# 
+#  This file provides performance tests for comparison of tcl-speed
+#  of timer events (event-driven tcl-handling).
+#
+# ------------------------------------------------------------------------
+# 
+# Copyright (c) 2014 Serg G. Brester (aka sebres)
+# 
+# See the file "license.terms" for information on usage and redistribution
+# of this file.
+# 
+
+
+if {![namespace exists ::tclTestPerf]} {
+  source [file join [file dirname [info script]] test-performance.tcl]
+}
+
+
+namespace eval ::tclTestPerf-Timer-Event {
+
+namespace path {::tclTestPerf}
+
+proc test-queue {{reptime {1000 10000}}} {
+
+  set howmuch [lindex $reptime 1]
+
+  # because of extremely short measurement times by tests below, wait a little bit (warming-up),
+  # to minimize influence of the time-gradation (just for better dispersion resp. result-comparison)
+  timerate {after 0} 156
+
+  puts "*** up to $howmuch events ***"
+  # single iteration by update, so using -no-result (measure only):
+  _test_run -no-result $reptime [string map [list \{*\}\$reptime $reptime \$howmuch $howmuch \\# \#] {
+    # generate up to $howmuch idle-events:
+    {after idle {set foo bar}}
+    # update / after idle:
+    {update; if {![llength [after info]]} break}
+    
+    # generate up to $howmuch idle-events:
+    {after idle {set foo bar}}
+    # update idletasks / after idle:
+    {update idletasks; if {![llength [after info]]} break}
+
+    # generate up to $howmuch immediate events:
+    {after 0 {set foo bar}}
+    # update / after 0:
+    {update; if {![llength [after info]]} break}
+    
+    # generate up to $howmuch 1-ms events:
+    {after 1 {set foo bar}}
+    setup {after 1}
+    # update / after 1:
+    {update; if {![llength [after info]]} break}
+
+    # generate up to $howmuch immediate events (+ 1 event of the second generation):
+    {after 0 {after 0 {}}}
+    # update / after 0 (double generation):
+    {update; if {![llength [after info]]} break}
+
+    # cancel forwards "after idle" / $howmuch idle-events in queue:
+    setup {set i 0; timerate {set ev([incr i]) [after idle {set foo bar}]} {*}$reptime}
+    setup {set le $i; set i 0; list 1 .. $le; # cancel up to $howmuch events}
+    {after cancel $ev([incr i]); if {$i >= $le} break}
+    cleanup {update; unset -nocomplain ev}
+    # cancel backwards "after idle" / $howmuch idle-events in queue:
+    setup {set i 0; timerate {set ev([incr i]) [after idle {set foo bar}]} {*}$reptime}
+    setup {set le $i; incr i; list $le .. 1; # cancel up to $howmuch events}
+    {after cancel $ev([incr i -1]); if {$i <= 1} break}
+    cleanup {update; unset -nocomplain ev}
+
+    # cancel forwards "after 0" / $howmuch timer-events in queue:
+    setup {set i 0; timerate {set ev([incr i]) [after 0 {set foo bar}]} {*}$reptime}
+    setup {set le $i; set i 0; list 1 .. $le; # cancel up to $howmuch events}
+    {after cancel $ev([incr i]); if {$i >= $howmuch} break}
+    cleanup {update; unset -nocomplain ev}
+    # cancel backwards "after 0" / $howmuch timer-events in queue:
+    setup {set i 0; timerate {set ev([incr i]) [after 0 {set foo bar}]} {*}$reptime}
+    setup {set le $i; incr i; list $le .. 1; # cancel up to $howmuch events}
+    {after cancel $ev([incr i -1]); if {$i <= 1} break}
+    cleanup {update; unset -nocomplain ev}
+    
+    # end $howmuch events.
+    cleanup {if [llength [after info]] {error "unexpected: [llength [after info]] events are still there."}}
+  }]
+}
+
+proc test-access {{reptime {1000 5000}}} {
+  set howmuch [lindex $reptime 1]
+
+  _test_run $reptime [string map [list \{*\}\$reptime $reptime \$howmuch $howmuch] {
+    # event random access: after idle + after info (by $howmuch events)
+    setup {set i -1; timerate {set ev([incr i]) [after idle {}]} {*}$reptime}
+    {after info $ev([expr {int(rand()*$i)}])}
+    cleanup {update; unset -nocomplain ev}
+    # event random access: after 0 + after info (by $howmuch events)
+    setup {set i -1; timerate {set ev([incr i]) [after 0 {}]} {*}$reptime}
+    {after info $ev([expr {int(rand()*$i)}])}
+    cleanup {update; unset -nocomplain ev}
+
+    # end $howmuch events.
+    cleanup {if [llength [after info]] {error "unexpected: [llength [after info]] events are still there."}}
+  }]
+}
+
+proc test-exec {{reptime 1000}} {
+  _test_run $reptime {
+    # after idle + after cancel
+    {after cancel [after idle {set foo bar}]}
+    # after 0 + after cancel
+    {after cancel [after 0 {set foo bar}]}
+    # after idle + update idletasks
+    {after idle {set foo bar}; update idletasks}
+    # after idle + update
+    {after idle {set foo bar}; update}
+    # immediate: after 0 + update
+    {after 0 {set foo bar}; update}
+    # delayed: after 1 + update
+    {after 1 {set foo bar}; update}
+    # empty update:
+    {update}
+    # empty update idle tasks:
+    {update idletasks}
+
+    # simple shortest sleep:
+    {after 0}
+  }
+}
+
+proc test-nrt-capability {{reptime 1000}} {
+  _test_run $reptime {
+    # comparison values:
+    {after 0 {set a 5}; update}
+    {after 0 {set a 5}; vwait a}
+
+    # conditional vwait with very brief wait-time:
+    {after 1 {set a timeout}; vwait a; expr {$::a ne "timeout" ? 1 : "0[unset ::a]"}}
+    {after 0 {set a timeout}; vwait a; expr {$::a ne "timeout" ? 1 : "0[unset ::a]"}}
+  }
+}
+
+proc test-long {{reptime 1000}} {
+  _test_run $reptime {
+    # in-between important event by amount of idle events:
+    {time {after idle {after 30}} 10; after 1 {set important 1}; vwait important;}
+    cleanup {foreach i [after info] {after cancel $i}}
+    # in-between important event (of new generation) by amount of idle events:
+    {time {after idle {after 30}} 10; after 1 {after 0 {set important 1}}; vwait important;} 
+    cleanup {foreach i [after info] {after cancel $i}}
+  }
+}
+
+proc test {{reptime 1000}} {
+  test-exec $reptime
+  foreach howmuch {5000 50000} {
+    test-access [list $reptime $howmuch]
+  }
+  test-nrt-capability $reptime
+  test-long $reptime
+
+  puts ""
+  foreach howmuch { 10000 20000 40000 60000 } {
+    test-queue [list $reptime $howmuch]
+  }
+
+  puts \n**OK**
+}
+
+}; # end of ::tclTestPerf-Timer-Event
+
+# ------------------------------------------------------------------------
+
+# if calling direct:
+if {[info exists ::argv0] && [file tail $::argv0] eq [file tail [info script]]} {
+  array set in {-time 500}
+  array set in $argv
+  ::tclTestPerf-Timer-Event::test $in(-time)
+}
diff --git a/tests/cmdMZ.test b/tests/cmdMZ.test
index a5f3009..45231c8 100644
--- a/tests/cmdMZ.test
+++ b/tests/cmdMZ.test
@@ -342,6 +342,70 @@ test cmdMZ-5.7 {Tcl_TimeObjCmd: errors generate right trace} {
     invoked from within
 "time {error foo}"}}
 
+test cmdMZ-6.1 {Tcl_TimeRateObjCmd: basic format of command} {
+    list [catch {timerate} msg] $msg
+} {1 {wrong # args: should be "timerate ?-direct? ?-calibrate? ?-overhead double? command ?time ?max-count??"}}
+test cmdMZ-6.2.1 {Tcl_TimeRateObjCmd: basic format of command} {
+    list [catch {timerate a b c d} msg] $msg
+} {1 {wrong # args: should be "timerate ?-direct? ?-calibrate? ?-overhead double? command ?time ?max-count??"}}
+test cmdMZ-6.2.2 {Tcl_TimeRateObjCmd: basic format of command} {
+    list [catch {timerate a b c} msg] $msg
+} {1 {expected integer but got "b"}}
+test cmdMZ-6.2.3 {Tcl_TimeRateObjCmd: basic format of command} {
+    list [catch {timerate a b} msg] $msg
+} {1 {expected integer but got "b"}}
+test cmdMZ-6.3 {Tcl_TimeRateObjCmd: basic format of command} {
+    list [catch {timerate -overhead b {} a b} msg] $msg
+} {1 {expected floating-point number but got "b"}}
+test cmdMZ-6.4 {Tcl_TimeRateObjCmd: compile of script happens even with negative iteration counts} {
+    list [catch {timerate "foreach a {c d e} \{" -12456} msg] $msg
+} {1 {missing close-brace}}
+test cmdMZ-6.5 {Tcl_TimeRateObjCmd: result format and one iteration} {
+    regexp {^\d+.\d+ \ws/# 1 # \d+ #/sec \d+.\d+ nett-ms$} [timerate {} 0]
+} 1
+test cmdMZ-6.6 {Tcl_TimeRateObjCmd: slower commands take longer, but it remains almost the same time of measument} {
+    set m1 [timerate {after 0} 20]
+    set m2 [timerate {after 1} 20]
+    list \
+	[expr {[lindex $m1 0] < [lindex $m2 0]}] \
+	[expr {[lindex $m1 0] < 100}] \
+	[expr {[lindex $m2 0] >= 500}] \
+	[expr {[lindex $m1 2] > 1000}] \
+	[expr {[lindex $m2 2] <= 50}] \
+	[expr {[lindex $m1 4] > 10000}] \
+	[expr {[lindex $m2 4] < 10000}] \
+	[expr {[lindex $m1 6] > 10 && [lindex $m1 6] < 50}] \
+	[expr {[lindex $m2 6] > 10 && [lindex $m2 6] < 50}]
+} [lrepeat 9 1]
+test cmdMZ-6.7 {Tcl_TimeRateObjCmd: errors generate right trace} {
+    list [catch {timerate {error foo} 1} msg] $msg $::errorInfo
+} {1 foo {foo
+    while executing
+"error foo"
+    invoked from within
+"timerate {error foo} 1"}}
+test cmdMZ-6.8 {Tcl_TimeRateObjCmd: allow (conditional) break from timerate} {
+    set m1 [timerate {break}]
+    list \
+	[expr {[lindex $m1 0] < 1000}] \
+	[expr {[lindex $m1 2] == 1}] \
+	[expr {[lindex $m1 4] > 1000}] \
+	[expr {[lindex $m1 6] < 10}]
+} {1 1 1 1}
+test cmdMZ-6.9 {Tcl_TimeRateObjCmd: max count of iterations} {
+    set m1 [timerate {} 1000 5];	# max-count wins
+    set m2 [timerate {after 20} 1 5];	# max-time wins
+    list [lindex $m1 2] [lindex $m2 2]
+} {5 1}
+test cmdMZ-6.10 {Tcl_TimeRateObjCmd: huge overhead cause 0us result} {
+    set m1 [timerate -overhead 1e6 {after 10} 100 1]
+    list \
+	[expr {[lindex $m1 0] == 0.0}] \
+	[expr {[lindex $m1 2] == 1}] \
+	[expr {[lindex $m1 4] == 1000000}] \
+	[expr {[lindex $m1 6] <= 0.001}]
+} {1 1 1 1}
+
 # The tests for Tcl_WhileObjCmd are in while.test
 
 # cleanup
diff --git a/tools/tcltk-man2html-utils.tcl b/tools/tcltk-man2html-utils.tcl
index b69e601..5a4550b 100644
--- a/tools/tcltk-man2html-utils.tcl
+++ b/tools/tcltk-man2html-utils.tcl
@@ -149,6 +149,7 @@ proc process-text {text} {
 	    {\(em}	"&#8212;" \
 	    {\(en}	"&#8211;" \
 	    {\(fm}	"&#8242;" \
+	    {\(mc}	"&#181;" \
 	    {\(mu}	"&#215;" \
 	    {\(mi}	"&#8722;" \
 	    {\(->}	"<font size=\"+1\">&#8594;</font>" \
diff --git a/unix/tclUnixTime.c b/unix/tclUnixTime.c
index 6a73ac2..d95d39b 100644
--- a/unix/tclUnixTime.c
+++ b/unix/tclUnixTime.c
@@ -87,6 +87,32 @@ TclpGetSeconds(void)
 /*
  *----------------------------------------------------------------------
  *
+ * TclpGetMicroseconds --
+ *
+ *	This procedure returns the number of microseconds from the epoch.
+ *	On most Unix systems the epoch is Midnight Jan 1, 1970 GMT.
+ *
+ * Results:
+ *	Number of microseconds from the epoch.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_WideInt
+TclpGetMicroseconds(void)
+{
+    Tcl_Time time;
+
+    tclGetTimeProcPtr(&time, tclTimeClientData);
+    return ((Tcl_WideInt)time.sec)*1000000 + time.usec;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * TclpGetClicks --
  *
  *	This procedure returns a value that represents the highest resolution
@@ -219,6 +245,51 @@ TclpWideClicksToNanoseconds(
 
     return nsec;
 }
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpWideClickInMicrosec --
+ *
+ *	This procedure return scale to convert click values from the 
+ *	TclpGetWideClicks native resolution to microsecond resolution
+ *	and back.
+ *
+ * Results:
+ * 	1 click in microseconds as double.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+double
+TclpWideClickInMicrosec(void)
+{
+    if (tclGetTimeProcPtr != NativeGetTime) {
+	return 1.0;
+    } else {
+#ifdef MAC_OSX_TCL
+	static int initialized = 0;
+	static double scale = 0.0;
+
+	if (initialized) {
+	    return scale;
+	} else {
+	    mach_timebase_info_data_t tb;
+
+	    mach_timebase_info(&tb);
+	    /* value of tb.numer / tb.denom = 1 click in nanoseconds */
+	    scale = ((double)tb.numer) / tb.denom / 1000;
+	    initialized = 1;
+	    return scale;
+	}
+#else
+#error Wide high-resolution clicks not implemented on this platform
+#endif
+    }
+}
 #endif /* TCL_WIDE_CLICKS */
 
 /*
diff --git a/win/tclWinTime.c b/win/tclWinTime.c
index dd603d1..19c53c8 100644
--- a/win/tclWinTime.c
+++ b/win/tclWinTime.c
@@ -53,6 +53,7 @@ typedef struct {
 				 * initialized. */
     int perfCounterAvailable;	/* Flag == 1 if the hardware has a performance
 				 * counter. */
+    DWORD calibrationInterv;	/* Calibration interval in seconds (start 1 sec) */
     HANDLE calibrationThread;	/* Handle to the thread that keeps the virtual
 				 * clock calibrated. */
     HANDLE readyEvent;		/* System event used to trigger the requesting
@@ -63,7 +64,6 @@ typedef struct {
     LARGE_INTEGER nominalFreq;	/* Nominal frequency of the system performance
 				 * counter, that is, the value returned from
 				 * QueryPerformanceFrequency. */
-
     /*
      * The following values are used for calculating virtual time. Virtual
      * time is always equal to:
@@ -76,6 +76,8 @@ typedef struct {
     ULARGE_INTEGER fileTimeLastCall;
     LARGE_INTEGER perfCounterLastCall;
     LARGE_INTEGER curCounterFreq;
+    LARGE_INTEGER posixEpoch;	/* Posix epoch expressed as 100-ns ticks since
+				 * the windows epoch. */
 
     /*
      * Data used in developing the estimate of performance counter frequency
@@ -92,6 +94,7 @@ static TimeInfo timeInfo = {
     { NULL, 0, 0, NULL, NULL, 0 },
     0,
     0,
+    1,
     (HANDLE) NULL,
     (HANDLE) NULL,
     (HANDLE) NULL,
@@ -100,11 +103,13 @@ static TimeInfo timeInfo = {
     (ULARGE_INTEGER) (DWORDLONG) 0,
     (LARGE_INTEGER) (Tcl_WideInt) 0,
     (LARGE_INTEGER) (Tcl_WideInt) 0,
+    (LARGE_INTEGER) (Tcl_WideInt) 0,
 #else
-    0,
-    0,
-    0,
-    0,
+    {0, 0},
+    {0, 0},
+    {0, 0},
+    {0, 0},
+    {0, 0},
 #endif
     { 0 },
     { 0 },
@@ -112,6 +117,17 @@ static TimeInfo timeInfo = {
 };
 
 /*
+ * Scale to convert wide click values from the TclpGetWideClicks native
+ * resolution to microsecond resolution and back.
+ */
+static struct {
+    int initialized;		/* 1 if initialized, 0 otherwise */
+    int perfCounter;		/* 1 if performance counter usable for wide clicks */
+    double microsecsScale;	/* Denominator scale between clock / microsecs */
+} wideClick = {0, 0.0};
+
+
+/*
  * Declarations for functions defined later in this file.
  */
 
@@ -127,6 +143,7 @@ static Tcl_WideInt	AccumulateSample(Tcl_WideInt perfCounter,
 			    Tcl_WideUInt fileTime);
 static void		NativeScaleTime(Tcl_Time* timebuf,
 			    ClientData clientData);
+static Tcl_WideInt	NativeGetMicroseconds(void);
 static void		NativeGetTime(Tcl_Time* timebuf,
 			    ClientData clientData);
 
@@ -158,10 +175,19 @@ ClientData tclTimeClientData = NULL;
 unsigned long
 TclpGetSeconds(void)
 {
-    Tcl_Time t;
+    Tcl_WideInt usecSincePosixEpoch;
+
+    /* Try to use high resolution timer */
+    if ( tclGetTimeProcPtr == NativeGetTime
+      && (usecSincePosixEpoch = NativeGetMicroseconds())
+    ) {
+	return usecSincePosixEpoch / 1000000;
+    } else {
+	Tcl_Time t;
 
-    tclGetTimeProcPtr(&t, tclTimeClientData);	/* Tcl_GetTime inlined. */
-    return t.sec;
+	tclGetTimeProcPtr(&t, tclTimeClientData);	/* Tcl_GetTime inlined. */
+	return t.sec;
+    }
 }
 
 /*
@@ -186,19 +212,147 @@ TclpGetSeconds(void)
 unsigned long
 TclpGetClicks(void)
 {
-    /*
-     * Use the Tcl_GetTime abstraction to get the time in microseconds, as
-     * nearly as we can, and return it.
-     */
+    Tcl_WideInt usecSincePosixEpoch;
 
-    Tcl_Time now;		/* Current Tcl time */
-    unsigned long retval;	/* Value to return */
+    /* Try to use high resolution timer */
+    if ( tclGetTimeProcPtr == NativeGetTime
+      && (usecSincePosixEpoch = NativeGetMicroseconds())
+    ) {
+	return (unsigned long)usecSincePosixEpoch;
+    } else {
+	/*
+	* Use the Tcl_GetTime abstraction to get the time in microseconds, as
+	* nearly as we can, and return it.
+	*/
 
-    tclGetTimeProcPtr(&now, tclTimeClientData);	/* Tcl_GetTime inlined */
+	Tcl_Time now;		/* Current Tcl time */
 
-    retval = (now.sec * 1000000) + now.usec;
-    return retval;
+	tclGetTimeProcPtr(&now, tclTimeClientData);	/* Tcl_GetTime inlined */
+	return (unsigned long)(now.sec * 1000000) + now.usec;
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpGetWideClicks --
+ *
+ *	This procedure returns a WideInt value that represents the highest
+ *	resolution clock in microseconds available on the system.
+ *
+ * Results:
+ *	Number of microseconds (from some start time).
+ *
+ * Side effects:
+ *	This should be used for time-delta resp. for measurement purposes
+ *	only, because on some platforms can return microseconds from some
+ *	start time (not from the epoch).
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_WideInt
+TclpGetWideClicks(void)
+{
+    LARGE_INTEGER curCounter;
+
+    if (!wideClick.initialized) {
+	LARGE_INTEGER perfCounterFreq;
+
+	/*
+	 * The frequency of the performance counter is fixed at system boot and
+	 * is consistent across all processors. Therefore, the frequency need 
+	 * only be queried upon application initialization.
+	 */
+	if (QueryPerformanceFrequency(&perfCounterFreq)) {
+	    wideClick.perfCounter = 1;
+	    wideClick.microsecsScale = 1000000.0 / perfCounterFreq.QuadPart;
+	} else {
+	    /* fallback using microseconds */
+	    wideClick.perfCounter = 0;
+	    wideClick.microsecsScale = 1;
+	}
+	
+	wideClick.initialized = 1;
+    }
+    if (wideClick.perfCounter) {
+	if (QueryPerformanceCounter(&curCounter)) {
+	    return (Tcl_WideInt)curCounter.QuadPart;
+	}
+	/* fallback using microseconds */
+	wideClick.perfCounter = 0;
+	wideClick.microsecsScale = 1;
+	return TclpGetMicroseconds();
+    } else {
+    	return TclpGetMicroseconds();
+    }
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpWideClickInMicrosec --
+ *
+ *	This procedure return scale to convert wide click values from the 
+ *	TclpGetWideClicks native resolution to microsecond resolution
+ *	and back.
+ *
+ * Results:
+ * 	1 click in microseconds as double.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
 
+double
+TclpWideClickInMicrosec(void)
+{
+    if (!wideClick.initialized) {
+    	(void)TclpGetWideClicks();	/* initialize */
+    }
+    return wideClick.microsecsScale;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * TclpGetMicroseconds --
+ *
+ *	This procedure returns a WideInt value that represents the highest
+ *	resolution clock in microseconds available on the system.
+ *
+ * Results:
+ *	Number of microseconds (from the epoch).
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+Tcl_WideInt 
+TclpGetMicroseconds(void)
+{
+    Tcl_WideInt usecSincePosixEpoch;
+
+    /* Try to use high resolution timer */
+    if ( tclGetTimeProcPtr == NativeGetTime
+      && (usecSincePosixEpoch = NativeGetMicroseconds())
+    ) {
+	return usecSincePosixEpoch;
+    } else {
+	/*
+	* Use the Tcl_GetTime abstraction to get the time in microseconds, as
+	* nearly as we can, and return it.
+	*/
+
+	Tcl_Time now;
+
+	tclGetTimeProcPtr(&now, tclTimeClientData);	/* Tcl_GetTime inlined */
+	return (((Tcl_WideInt)now.sec) * 1000000) + now.usec;
+    }
 }
 
 /*
@@ -227,7 +381,17 @@ void
 Tcl_GetTime(
     Tcl_Time *timePtr)		/* Location to store time information. */
 {
-    tclGetTimeProcPtr(timePtr, tclTimeClientData);
+    Tcl_WideInt usecSincePosixEpoch;
+
+    /* Try to use high resolution timer */
+    if ( tclGetTimeProcPtr == NativeGetTime
+      && (usecSincePosixEpoch = NativeGetMicroseconds())
+    ) {
+	timePtr->sec = (long) (usecSincePosixEpoch / 1000000);
+	timePtr->usec = (unsigned long) (usecSincePosixEpoch % 1000000);
+    } else {
+    	tclGetTimeProcPtr(timePtr, tclTimeClientData);
+    }
 }
 
 /*
@@ -260,13 +424,14 @@ NativeScaleTime(
 /*
  *----------------------------------------------------------------------
  *
- * NativeGetTime --
+ * NativeGetMicroseconds --
  *
- *	TIP #233: Gets the current system time in seconds and microseconds
- *	since the beginning of the epoch: 00:00 UCT, January 1, 1970.
+ *	Gets the current system time in microseconds since the beginning
+ *	of the epoch: 00:00 UCT, January 1, 1970.
  *
  * Results:
- *	Returns the current time in timePtr.
+ *	Returns the wide integer with number of microseconds from the epoch, or
+ *	0 if high resolution timer is not available.
  *
  * Side effects:
  *	On the first call, initializes a set of static variables to keep track
@@ -279,13 +444,20 @@ NativeScaleTime(
  *----------------------------------------------------------------------
  */
 
-static void
-NativeGetTime(
-    Tcl_Time *timePtr,
-    ClientData clientData)
-{
-    struct _timeb t;
+static inline Tcl_WideInt
+NativeCalc100NsTicks(
+    ULONGLONG fileTimeLastCall,
+    LONGLONG perfCounterLastCall,
+    LONGLONG curCounterFreq,
+    LONGLONG curCounter
+) {
+    return fileTimeLastCall + 
+	((curCounter - perfCounterLastCall) * 10000000 / curCounterFreq);
+}
 
+static Tcl_WideInt
+NativeGetMicroseconds(void)
+{
     /*
      * Initialize static storage on the first trip through.
      *
@@ -296,6 +468,10 @@ NativeGetTime(
     if (!timeInfo.initialized) {
 	TclpInitLock();
 	if (!timeInfo.initialized) {
+
+	    timeInfo.posixEpoch.LowPart = 0xD53E8000;
+	    timeInfo.posixEpoch.HighPart = 0x019DB1DE;
+
 	    timeInfo.perfCounterAvailable =
 		    QueryPerformanceFrequency(&timeInfo.nominalFreq);
 
@@ -400,22 +576,12 @@ NativeGetTime(
 	 * time.
 	 */
 
-	ULARGE_INTEGER fileTimeLastCall;
-	LARGE_INTEGER perfCounterLastCall, curCounterFreq;
+	ULONGLONG fileTimeLastCall;
+	LONGLONG perfCounterLastCall, curCounterFreq;
 				/* Copy with current data of calibration cycle */
 
 	LARGE_INTEGER curCounter;
 				/* Current performance counter. */
-	Tcl_WideInt curFileTime;/* Current estimated time, expressed as 100-ns
-				 * ticks since the Windows epoch. */
-	static LARGE_INTEGER posixEpoch;
-				/* Posix epoch expressed as 100-ns ticks since
-				 * the windows epoch. */
-	Tcl_WideInt usecSincePosixEpoch;
-				/* Current microseconds since Posix epoch. */
-
-	posixEpoch.LowPart = 0xD53E8000;
-	posixEpoch.HighPart = 0x019DB1DE;
 
 	QueryPerformanceCounter(&curCounter);
 
@@ -424,21 +590,18 @@ NativeGetTime(
 	 */
 	EnterCriticalSection(&timeInfo.cs);
 
-	fileTimeLastCall.QuadPart = timeInfo.fileTimeLastCall.QuadPart;
-	perfCounterLastCall.QuadPart = timeInfo.perfCounterLastCall.QuadPart;
-	curCounterFreq.QuadPart = timeInfo.curCounterFreq.QuadPart;
+	fileTimeLastCall = timeInfo.fileTimeLastCall.QuadPart;
+	perfCounterLastCall = timeInfo.perfCounterLastCall.QuadPart;
+	curCounterFreq = timeInfo.curCounterFreq.QuadPart;
 
 	LeaveCriticalSection(&timeInfo.cs);
 
 	/*
 	 * If calibration cycle occurred after we get curCounter
 	 */
-	if (curCounter.QuadPart <= perfCounterLastCall.QuadPart) {
-	    usecSincePosixEpoch =
-		(fileTimeLastCall.QuadPart - posixEpoch.QuadPart) / 10;
-	    timePtr->sec = (long) (usecSincePosixEpoch / 1000000);
-	    timePtr->usec = (unsigned long) (usecSincePosixEpoch % 1000000);
-	    return;
+	if (curCounter.QuadPart <= perfCounterLastCall) {
+	    /* Calibrated file-time is saved from posix in 100-ns ticks */
+	    return fileTimeLastCall / 10;
 	}
 
 	/*
@@ -451,27 +614,62 @@ NativeGetTime(
 	 * loop should recover.
 	 */
 
-	if (curCounter.QuadPart - perfCounterLastCall.QuadPart <
-		11 * curCounterFreq.QuadPart / 10
+	if (curCounter.QuadPart - perfCounterLastCall <
+		11 * curCounterFreq * timeInfo.calibrationInterv / 10
 	) {
-	    curFileTime = fileTimeLastCall.QuadPart +
-		 ((curCounter.QuadPart - perfCounterLastCall.QuadPart)
-		    * 10000000 / curCounterFreq.QuadPart);
-
-	    usecSincePosixEpoch = (curFileTime - posixEpoch.QuadPart) / 10;
-	    timePtr->sec = (long) (usecSincePosixEpoch / 1000000);
-	    timePtr->usec = (unsigned long) (usecSincePosixEpoch % 1000000);
-	    return;
+	    /* Calibrated file-time is saved from posix in 100-ns ticks */
+	    return NativeCalc100NsTicks(fileTimeLastCall,
+		perfCounterLastCall, curCounterFreq, curCounter.QuadPart) / 10;
 	}
     }
 
     /*
-     * High resolution timer is not available. Just use ftime.
+     * High resolution timer is not available.
      */
+    return 0;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * NativeGetTime --
+ *
+ *	TIP #233: Gets the current system time in seconds and microseconds
+ *	since the beginning of the epoch: 00:00 UCT, January 1, 1970.
+ *
+ * Results:
+ *	Returns the current time in timePtr.
+ *
+ * Side effects:
+ *	See NativeGetMicroseconds for more information.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+NativeGetTime(
+    Tcl_Time *timePtr,
+    ClientData clientData)
+{
+    Tcl_WideInt usecSincePosixEpoch;
+
+    /*
+     * Try to use high resolution timer.
+     */
+    if ( (usecSincePosixEpoch = NativeGetMicroseconds()) ) {
+	timePtr->sec = (long) (usecSincePosixEpoch / 1000000);
+	timePtr->usec = (unsigned long) (usecSincePosixEpoch % 1000000);
+    } else {
+	/*
+	* High resolution timer is not available. Just use ftime.
+	*/
+
+	struct _timeb t;
 
-    _ftime(&t);
-    timePtr->sec = (long)t.time;
-    timePtr->usec = t.millitm * 1000;
+	_ftime(&t);
+	timePtr->sec = (long)t.time;
+	timePtr->usec = t.millitm * 1000;
+    }
 }
 
 /*
@@ -492,6 +690,8 @@ NativeGetTime(
  *----------------------------------------------------------------------
  */
 
+void TclWinResetTimerResolution(void);
+
 static void
 StopCalibration(
     ClientData unused)		/* Client data is unused */
@@ -782,6 +982,8 @@ CalibrationThread(
     QueryPerformanceFrequency(&timeInfo.curCounterFreq);
     timeInfo.fileTimeLastCall.LowPart = curFileTime.dwLowDateTime;
     timeInfo.fileTimeLastCall.HighPart = curFileTime.dwHighDateTime;
+    /* Calibrated file-time will be saved from posix in 100-ns ticks */
+    timeInfo.fileTimeLastCall.QuadPart -= timeInfo.posixEpoch.QuadPart;
 
     ResetCounterSamples(timeInfo.fileTimeLastCall.QuadPart,
 	    timeInfo.perfCounterLastCall.QuadPart,
@@ -841,6 +1043,7 @@ UpdateTimeEachSecond(void)
 				/* Current value returned from
 				 * QueryPerformanceCounter. */
     FILETIME curSysTime;	/* Current system time. */
+    static LARGE_INTEGER lastFileTime; /* File time of the previous calibration */
     LARGE_INTEGER curFileTime;	/* File time at the time this callback was
 				 * scheduled. */
     Tcl_WideInt estFreq;	/* Estimated perf counter frequency. */
@@ -852,15 +1055,24 @@ UpdateTimeEachSecond(void)
 				 * step over 1 second. */
 
     /*
-     * Sample performance counter and system time.
+     * Sample performance counter and system time (from posix epoch).
      */
 
-    QueryPerformanceCounter(&curPerfCounter);
     GetSystemTimeAsFileTime(&curSysTime);
     curFileTime.LowPart = curSysTime.dwLowDateTime;
     curFileTime.HighPart = curSysTime.dwHighDateTime;
-
-    EnterCriticalSection(&timeInfo.cs);
+    curFileTime.QuadPart -= timeInfo.posixEpoch.QuadPart;
+    /* If calibration still not needed (check for possible time switch) */
+    if ( curFileTime.QuadPart > lastFileTime.QuadPart
+      && curFileTime.QuadPart < lastFileTime.QuadPart +
+      				    (timeInfo.calibrationInterv * 10000000)
+    ) {
+    	/* again in next one second */
+	return;
+    }
+    QueryPerformanceCounter(&curPerfCounter);
+    
+    lastFileTime.QuadPart = curFileTime.QuadPart;
 
     /*
      * We devide by timeInfo.curCounterFreq.QuadPart in several places. That
@@ -872,7 +1084,6 @@ UpdateTimeEachSecond(void)
      */
 
     if (timeInfo.curCounterFreq.QuadPart == 0){
-	LeaveCriticalSection(&timeInfo.cs);
 	timeInfo.perfCounterAvailable = 0;
 	return;
     }
@@ -911,12 +1122,9 @@ UpdateTimeEachSecond(void)
      * is estFreq * 20000000 / (vt1 - vt0)
      */
 
-    vt0 = 10000000 * (curPerfCounter.QuadPart
-		- timeInfo.perfCounterLastCall.QuadPart)
-	    / timeInfo.curCounterFreq.QuadPart
-	    + timeInfo.fileTimeLastCall.QuadPart;
-    vt1 = 20000000 + curFileTime.QuadPart;
-
+    vt0 = NativeCalc100NsTicks(timeInfo.fileTimeLastCall.QuadPart,
+	    timeInfo.perfCounterLastCall.QuadPart, timeInfo.curCounterFreq.QuadPart,
+	    curPerfCounter.QuadPart);
     /*
      * If we've gotten more than a second away from system time, then drifting
      * the clock is going to be pretty hopeless. Just let it jump. Otherwise,
@@ -925,21 +1133,75 @@ UpdateTimeEachSecond(void)
 
     tdiff = vt0 - curFileTime.QuadPart;
     if (tdiff > 10000000 || tdiff < -10000000) {
-	timeInfo.fileTimeLastCall.QuadPart = curFileTime.QuadPart;
-	timeInfo.curCounterFreq.QuadPart = estFreq;
+    	/* jump to current system time, use curent estimated frequency */
+    	vt0 = curFileTime.QuadPart;
     } else {
-	driftFreq = estFreq * 20000000 / (vt1 - vt0);
+    	/* calculate new frequency and estimate drift to the next second */
+	vt1 = 20000000 + curFileTime.QuadPart;
+	driftFreq = (estFreq * 20000000 / (vt1 - vt0));
+	/* 
+	 * Avoid too large drifts (only half of the current difference),
+	 * that allows also be more accurate (aspire to the smallest tdiff),
+	 * so then we can prolong calibration interval by tdiff < 100000
+	 */
+	driftFreq = timeInfo.curCounterFreq.QuadPart +
+		(driftFreq - timeInfo.curCounterFreq.QuadPart) / 2;
 
-	if (driftFreq > 1003*estFreq/1000) {
-	    driftFreq = 1003*estFreq/1000;
-	} else if (driftFreq < 997*estFreq/1000) {
-	    driftFreq = 997*estFreq/1000;
+	/* 
+	 * Average between estimated, 2 current and 5 drifted frequencies,
+	 * (do the soft drifting as possible)
+	 */
+	estFreq = (estFreq + 2 * timeInfo.curCounterFreq.QuadPart + 5 * driftFreq) / 8;
+    }
+    
+    /* Avoid too large discrepancy from nominal frequency */
+    if (estFreq > 1003*timeInfo.nominalFreq.QuadPart/1000) {
+	estFreq = 1003*timeInfo.nominalFreq.QuadPart/1000;
+	vt0 = curFileTime.QuadPart;
+    } else if (estFreq < 997*timeInfo.nominalFreq.QuadPart/1000) {
+	estFreq = 997*timeInfo.nominalFreq.QuadPart/1000;
+	vt0 = curFileTime.QuadPart;
+    } else if (vt0 != curFileTime.QuadPart) {
+	/* 
+	 * Be sure the clock ticks never backwards (avoid it by negative drifting)
+	 * just compare native time (in 100-ns) before and hereafter using 
+	 * new calibrated values) and do a small adjustment (short time freeze)
+	 */
+	LARGE_INTEGER newPerfCounter;
+	Tcl_WideInt nt0, nt1;
+
+	QueryPerformanceCounter(&newPerfCounter);
+	nt0 = NativeCalc100NsTicks(timeInfo.fileTimeLastCall.QuadPart,
+		timeInfo.perfCounterLastCall.QuadPart, timeInfo.curCounterFreq.QuadPart,
+		newPerfCounter.QuadPart);
+	nt1 = NativeCalc100NsTicks(vt0,
+		curPerfCounter.QuadPart, estFreq,
+		newPerfCounter.QuadPart);
+	if (nt0 > nt1) { /* drifted backwards, try to compensate with new base */
+	    /* first adjust with a micro jump (short frozen time is acceptable) */
+	    vt0 += nt0 - nt1;
+	    /* if drift unavoidable (e. g. we had a time switch), then reset it */
+	    vt1 = vt0 - curFileTime.QuadPart;
+	    if (vt1 > 10000000 || vt1 < -10000000) {
+	    	/* larger jump resp. shift relative new file-time */
+	    	vt0 = curFileTime.QuadPart;
+	    }
 	}
+    }
+
+    /* In lock commit new values to timeInfo (hold lock as short as possible) */
+    EnterCriticalSection(&timeInfo.cs);
 
-	timeInfo.fileTimeLastCall.QuadPart = vt0;
-	timeInfo.curCounterFreq.QuadPart = driftFreq;
+    /* grow calibration interval up to 10 seconds (if still precise enough) */
+    if (tdiff < -100000 || tdiff > 100000) {
+	/* too long drift - reset calibration interval to 1000 second */
+	timeInfo.calibrationInterv = 1;
+    } else if (timeInfo.calibrationInterv < 10) {
+	timeInfo.calibrationInterv++;
     }
 
+    timeInfo.fileTimeLastCall.QuadPart = vt0;
+    timeInfo.curCounterFreq.QuadPart = estFreq;
     timeInfo.perfCounterLastCall.QuadPart = curPerfCounter.QuadPart;
 
     LeaveCriticalSection(&timeInfo.cs);