[svn-r14442] Modified metadata cache to adapt more quickly to the insertion of a

large entry, or to a large increases in the size of an existing entry.
This required some additions to the cache configuration structure, and
thus will require changes in the metadata cache documentation.

The basic idea is to monitor the size of entries as they are loaded,
inserted, or increased in size.  If the size of the entry (or increase)
exceeds some user selected fraction of the size of the cache, increase
the size of the cache.

Note that this fix was designed quickly -- while it deals with the 
use case that exposed the problem, we may have to revisit the issue
later.

Tested serial and parallel on Phoenix, and h5committest.

1 files changed, 81 insertions, 24 deletions

diff --git a/src/H5Cprivate.h b/src/H5Cprivate.h
index d365755..10585a3 100644
--- a/src/H5Cprivate.h
+++ b/src/H5Cprivate.h
@@ -37,7 +37,7 @@
 #include "H5Fprivate.h"		/* File access				*/
 
 
-#define H5C_DO_SANITY_CHECKS		0
+#define H5C_DO_SANITY_CHECKS		1
 #define H5C_DO_EXTREME_SANITY_CHECKS	0
 
 /* This sanity checking constant was picked out of the air.  Increase
@@ -51,7 +51,7 @@
 /* H5C_COLLECT_CACHE_STATS controls overall collection of statistics
  * on cache activity.  In general, this #define should be set to 0.
  */
-#define H5C_COLLECT_CACHE_STATS	0
+#define H5C_COLLECT_CACHE_STATS	1
 
 /* H5C_COLLECT_CACHE_ENTRY_STATS controls collection of statistics
  * in individual cache entries.
@@ -587,7 +587,58 @@ typedef struct H5C_cache_entry_t
  *	above, this field contains the maximum number of bytes by which the
  *	cache size can be increased in a single re-size.
  *
- *
+ * flash_incr_mode:  Instance of the H5C_cache_flash_incr_mode enumerated
+ * 	type whose value indicates whether and by what algorithm we should
+ * 	make flash increases in the size of the cache to accomodate insertion
+ * 	of large entries and large increases in the size of a single entry.
+ *
+ * 	The addition of the flash increment mode was occasioned by performance
+ * 	problems that appear when a local heap is increased to a size in excess
+ * 	of the current cache size.  While the existing re-size code dealt with 
+ * 	this eventually, performance was very bad for the remainder of the 
+ * 	epoch.
+ * 	
+ * 	At present, there are two possible values for the flash_incr_mode:
+ *
+ * 	H5C_flash_incr__off:  Don't perform flash increases in the size of 
+ * 		the cache. 
+ *
+ *	H5C_flash_incr__add_space:  Let x be either the size of a newly 
+ *	        newly inserted entry, or the number of bytes by which the 
+ *	        size of an existing entry has been increased.
+ *
+ *	        If 
+ *	        	x > flash_threshold * current max cache size, 
+ *
+ *	       	increase the current maximum cache size by x * flash_multiple
+ *	       	less any free space in the cache, and start a new epoch.  For
+ *	       	now at least, pay no attention to the maximum increment.
+ *
+ *
+ *	With a little thought, it should be obvious that the above flash
+ *	cache size increase algorithm is not sufficient for all circumstances --
+ *	for example, suppose the user round robins through 
+ *	(1/flash_threshold) +1 groups, adding one data set to each on each 
+ *	pass.  Then all will increase in size at about the same time, requiring 
+ *	the max cache size to at least double to maintain acceptable 
+ *      performance, however the above flash increment algorithm will not be 
+ *	triggered.
+ *
+ *	Hopefully, the add space algorithm detailed above will be sufficient 
+ *	for the performance problems encountered to date.  However, we should 
+ *	expect to revisit the issue.
+ *
+ * flash_multiple: Double containing the multiple described above in the 
+ * 	H5C_flash_incr__add_space section of the discussion of the 
+ * 	flash_incr_mode	section.  This field is ignored unless flash_incr_mode 
+ * 	is H5C_flash_incr__add_space.
+ *
+ * flash_threshold: Double containing the factor by which current max cache size
+ *      is multiplied to obtain the size threshold for the add_space flash 
+ *      increment algorithm.  The field is ignored unless flash_incr_mode is 
+ *	H5C_flash_incr__add_space.
+ *
+ *	
  * Cache size decrease control fields:
  *
  * decr_mode: Instance of the H5C_cache_decr_mode enumerated type whose
@@ -701,6 +752,8 @@ typedef struct H5C_cache_entry_t
 #define H5C__DEF_AR_MIN_CLEAN_FRAC		0.5
 #define H5C__DEF_AR_INCREMENT			2.0
 #define H5C__DEF_AR_MAX_INCREMENT		((size_t)( 2 * 1024 * 1024))
+#define	H5C__DEF_AR_FLASH_MULTIPLE		1.0
+#define H5C__DEV_AR_FLASH_THRESHOLD		0.25
 #define H5C__DEF_AR_DECREMENT			0.9
 #define H5C__DEF_AR_MAX_DECREMENT		((size_t)( 1 * 1024 * 1024))
 #define H5C__DEF_AR_EPCHS_B4_EVICT		3
@@ -713,6 +766,7 @@ enum H5C_resize_status
 {
     in_spec,
     increase,
+    flash_increase,
     decrease,
     at_max_size,
     at_min_size,
@@ -733,45 +787,48 @@ typedef void (*H5C_auto_resize_rpt_fcn)(H5C_t * cache_ptr,
 typedef struct H5C_auto_size_ctl_t
 {
     /* general configuration fields: */
-    int32_t			version;
-    H5C_auto_resize_rpt_fcn	rpt_fcn;
+    int32_t				version;
+    H5C_auto_resize_rpt_fcn		rpt_fcn;
 
-    hbool_t			set_initial_size;
-    size_t			initial_size;
+    hbool_t				set_initial_size;
+    size_t				initial_size;
 
-    double			min_clean_fraction;
+    double				min_clean_fraction;
 
-    size_t			max_size;
-    size_t			min_size;
+    size_t				max_size;
+    size_t				min_size;
 
-    int64_t			epoch_length;
+    int64_t				epoch_length;
 
 
     /* size increase control fields: */
-    enum H5C_cache_incr_mode	incr_mode;
+    enum H5C_cache_incr_mode		incr_mode;
 
-    double			lower_hr_threshold;
+    double				lower_hr_threshold;
 
-    double			increment;
+    double				increment;
 
-    hbool_t			apply_max_increment;
-    size_t			max_increment;
+    hbool_t				apply_max_increment;
+    size_t				max_increment;
 
+    enum H5C_cache_flash_incr_mode	flash_incr_mode;
+    double				flash_multiple;
+    double				flash_threshold;
 
     /* size decrease control fields: */
-    enum H5C_cache_decr_mode	decr_mode;
+    enum H5C_cache_decr_mode		decr_mode;
 
-    double			upper_hr_threshold;
+    double				upper_hr_threshold;
 
-    double			decrement;
+    double				decrement;
 
-    hbool_t			apply_max_decrement;
-    size_t			max_decrement;
+    hbool_t				apply_max_decrement;
+    size_t				max_decrement;
 
-    int32_t			epochs_before_eviction;
+    int32_t				epochs_before_eviction;
 
-    hbool_t			apply_empty_reserve;
-    double			empty_reserve;
+    hbool_t				apply_empty_reserve;
+    double				empty_reserve;
 
 } H5C_auto_size_ctl_t;