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Diffstat (limited to 'README.mig-alloc-reform')
| -rw-r--r-- | README.mig-alloc-reform | 71 |
1 files changed, 0 insertions, 71 deletions
diff --git a/README.mig-alloc-reform b/README.mig-alloc-reform deleted file mode 100644 index 302812a..0000000 --- a/README.mig-alloc-reform +++ /dev/null @@ -1,71 +0,0 @@ -What is mig-alloc-reform? - 1. A massive simplification of the memory management in Tcl core. - a. removal of the Tcl stack, each BC allocates its own stacklet - b. TclStackAlloc is gone, replaced with ckalloc; goodbye to sometimes - hard sync problems - c. removal of the allocCache slot in struct Interp - d. retirement of the (unused) Tcl allocator USE_TCLALLOC; replacement - with a single-thread special case of zippy - e. unify all allocator options in a single file tclAlloc.c - d. exploit fast TSD via __thread where available (autoconferry still - missing, enable by hand with -DHAVE_FAST_TSD) - f. small improvements in zippy's memory usage: - . try to split blocks in the shared cache before allocating new - ones from the system - . use the same bucket for Tcl_Objs and smallest allocs - - 2. New allocator options - a. purify build (but stop using them, see below). This is suitable to - use with a preloaded malloc replacement - b. (~NEW) native build: call to sys malloc, but maintain zippy's - Tcl_Obj caches (per thread, if threads enabled). Can be switched to - run as a purify build via an env var at startup. This is suitable to - use with a preloaded malloc replacement. The threaded variant is new. - c. zippy build - d. (NEW) multi build: this is a build that can function as any of the - other three. Per default it runs as zippy, but can be switched to - native or purify via an env var at startup. May or may not be used - for deployment, but it will definitely be very useful for - development: no need to recompile in order to valgrind, just set an - env var! - - How do you use it? Options are: - 1. Don't pay any attention to it, build as always. You will get the same - allocator as before - 2. Select the build you want with compiler flags - -DTCL_ALLOCATOR=(aNATIVE|aPURIFY|aZIPPY|aMULTI) - 3. Select behaviour at startup: native can be switched to purify, multi - can be switched to any of the others. Define the env var - TCL_ALLOCATOR when starting up and you're good to go - - -** PERFORMANCE NOTES ** - * do enable HAVE_FAST_TSD on threaded build where available! Without - that it is probably slower than before. Note that __thread is not - available on macosx, but the "slow" version should be quite fast there - (or so they say) - * not measured, but: purify, native and zippy builds should be just as - fast as before. The obj-alloc macros have been removed while - developing. It is not certain that they provide a speedup, this will - be measured and acted accordingly - * multi build should be a only a tad slower, may even be suitable as - default build on all platforms - * zippy stats not enabled by default, -DZIPPY_STATS switches them on - -** TO DO LIST ** - * DEFINITELY - - test like crazy - - timings: versus older version (in unthreaded, fast-tsd and slow-tsd - builds). Determine if the obj-alloc macros should be reenabled - - autoconferry to auto-detect HAVE_FAST_TSD - - autoconferry to choose allocator flags? Keep USE_THREAD_ALLOC and - USE_TCLALLOC for back compat with external build scripts only (and - set them too!), but set also the new variants - TCL_ALLOCATOR=(aNATIVE|aPURIFY|aZIPPY|aMULTI) - - Makefile.in and autoconferry changes in windows, mac - - choose allocators from the command line instead of env vars? - - verify interaction with memdebug (should be 'none', but ...) - - * MAYBE - - build zippy as malloc-replacement, compile always aNATIVE and - preload alternatives |