[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, 18 insertions, 4 deletions

diff --git a/src/H5Cpkg.h b/src/H5Cpkg.h
index 949f923..7c04ea2 100644
--- a/src/H5Cpkg.h
+++ b/src/H5Cpkg.h
@@ -465,6 +465,18 @@
  *		all the ways this can happen, we simply set this flag when
  *		we receive a new configuration.
  *
+ * flash_size_increase_possible: Depending on the configuration data given
+ * 		in the resize_ctl field, it may or may not be possible
+ * 		for a flash size increase to occur.  We set this flag
+ * 		whenever we receive a new configuration so as to avoid 
+ * 		repeated calculations.
+ *
+ * flash_size_increase_threshold: If a flash cache size increase is possible,
+ * 		this field is used to store the minimum size of a new entry
+ * 		or size increase needed to trigger a flash cache size 
+ * 		increase.  Note that this field must be updated whenever 
+ * 		the size of the cache is changed.
+ *
  * size_decrease_possible:  Depending on the configuration data given
  *              in the resize_ctl field, it may or may not be possible
  *              to decrease the size of the cache.  Rather than test for
@@ -580,10 +592,10 @@
  *		equal to the array index has not been in cache when
  *		requested in the current epoch.
  *
- * write_protects:  Array of int64 of length H5C__MAX_NUM_TYPE_IDS + 1.  The cells
- * 		are used to record the number of times an entry with type id
- * 		equal to the array index has been write protected in the 
- * 		current epoch.
+ * write_protects:  Array of int64 of length H5C__MAX_NUM_TYPE_IDS + 1.  The 
+ *		cells are used to record the number of times an entry with 
+ *		type id equal to the array index has been write protected 
+ *		in the current epoch.
  *
  * 		Observe that (hits + misses) = (write_protects + read_protects).
  *
@@ -855,6 +867,8 @@ struct H5C_t
     H5C_cache_entry_t *	        dLRU_tail_ptr;
 
     hbool_t			size_increase_possible;
+    hbool_t			flash_size_increase_possible;
+    size_t			flash_size_increase_threshold; 
     hbool_t			size_decrease_possible;
     hbool_t			resize_enabled;
     hbool_t			cache_full;