Author: stefan2
Date: Mon Jan 5 19:40:32 2015
New Revision: 1649626
URL: http://svn.apache.org/r1649626
Log:
Remove the unused segment hit counter from the membuffer code.
It is kept up-to-date but never actually used anywhere.
* subversion/libsvn_subr/cache-membuffer.c
(svn_membuffer_t): Drop the HIT_COUNTER.
(drop_entry,
let_entry_age): One element less to update.
(svn_cache__membuffer_cache_create): One element less to initialize.
(increment_hit_counters): One element less to update. Update the
rationale for our overflow non-handling.
Modified:
subversion/trunk/subversion/libsvn_subr/cache-membuffer.c
Modified: subversion/trunk/subversion/libsvn_subr/cache-membuffer.c
URL:
http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_subr/cache-membuffer.c?rev=1649626&r1=1649625&r2=1649626&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_subr/cache-membuffer.c (original)
+++ subversion/trunk/subversion/libsvn_subr/cache-membuffer.c Mon Jan 5
19:40:32 2015
@@ -563,13 +563,6 @@ struct svn_membuffer_t
*/
apr_uint32_t used_entries;
- /* Sum of (read) hit counts of all used dictionary entries.
- * In conjunction used_entries used_entries, this is used calculate
- * the average hit count as part of the randomized LFU algorithm.
- */
- apr_uint64_t hit_count;
-
-
/* Total number of calls to membuffer_cache_get.
* Purely statistical information that may be used for profiling only.
* Updates are not synchronized and values may be nonsensicle on some
@@ -1027,7 +1020,6 @@ drop_entry(svn_membuffer_t *cache, entry
/* update global cache usage counters
*/
cache->used_entries--;
- cache->hit_count -= entry->hit_count;
cache->data_used -= entry->size;
/* extend the insertion window, if the entry happens to border it
@@ -1163,7 +1155,6 @@ let_entry_age(svn_membuffer_t *cache, en
if (hits_removed)
{
- cache->hit_count -= hits_removed;
entry->hit_count -= hits_removed;
}
else
@@ -1795,7 +1786,6 @@ svn_cache__membuffer_cache_create(svn_me
c[seg].max_entry_size = max_entry_size;
c[seg].used_entries = 0;
- c[seg].hit_count = 0;
c[seg].total_reads = 0;
c[seg].total_writes = 0;
c[seg].total_hits = 0;
@@ -2071,12 +2061,10 @@ static svn_error_t *
increment_hit_counters(svn_membuffer_t *cache, entry_t *entry)
{
/* To minimize the memory footprint of the cache index, we limit local
- * hit counters to 32 bits. These may overflow and we must make sure that
- * the global sums are still the sum of all local counters. */
- if (++entry->hit_count == 0)
- cache->hit_count -= APR_UINT32_MAX;
- else
- cache->hit_count++;
+ * hit counters to 32 bits. These may overflow but we don't really
+ * care because at worst, ENTRY will be dropped from cache once every
+ * few billion hits. */
+ ++entry->hit_count;
/* That one is for stats only. */
cache->total_hits++;
