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Replace the BufMgrLock with separate locks on the lookup hashtable and

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the freelist, plus per-buffer spinlocks that protect access to individual
shared buffer headers.  This requires abandoning a global freelist (since
the freelist is a global contention point), which shoots down ARC and 2Q
as well as plain LRU management.  Adopt a clock sweep algorithm instead.
Preliminary results show substantial improvement in multi-backend situations.
This commit is contained in:
Tom Lane
2005-03-04 20:21:07 +00:00
parent 5592a6cf46
commit 5d5087363d
18 changed files with 1410 additions and 1932 deletions
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46
src/backend/utils/misc/guc.c
View File

@@ -10,7 +10,7 @@
* Written by Peter Eisentraut <peter_e@gmx.net>.
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.253 2005/03/01 20:23:34 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.254 2005/03/04 20:21:06 tgl Exp $
*
*--------------------------------------------------------------------
*/
@@ -77,7 +77,6 @@ extern bool Log_disconnections;
extern DLLIMPORT bool check_function_bodies;
extern int CommitDelay;
extern int CommitSiblings;
extern int DebugSharedBuffers;
extern char *default_tablespace;
static const char *assign_log_destination(const char *value,
@@ -1230,15 +1229,6 @@ static struct config_int ConfigureNamesInt[] =
-1, -1, INT_MAX / 1000, NULL, NULL
},
{
{"debug_shared_buffers", PGC_POSTMASTER, STATS_MONITORING,
gettext_noop("Interval to report shared buffer status in seconds"),
NULL
},
&DebugSharedBuffers,
0, 0, 600, NULL, NULL
},
{
{"bgwriter_delay", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer sleep time between rounds in milliseconds"),
@@ -1249,21 +1239,21 @@ static struct config_int ConfigureNamesInt[] =
},
{
{"bgwriter_percent", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer percentage of dirty buffers to flush per round"),
{"bgwriter_lru_maxpages", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer maximum number of all pages to flush per round"),
NULL
},
&BgWriterPercent,
1, 0, 100, NULL, NULL
&bgwriter_lru_maxpages,
5, 0, 1000, NULL, NULL
},
{
{"bgwriter_maxpages", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer maximum number of pages to flush per round"),
{"bgwriter_all_maxpages", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer maximum number of LRU pages to flush per round"),
NULL
},
&BgWriterMaxPages,
100, 0, 1000, NULL, NULL
&bgwriter_all_maxpages,
5, 0, 1000, NULL, NULL
},
{
@@ -1394,6 +1384,24 @@ static struct config_real ConfigureNamesReal[] =
MAX_GEQO_SELECTION_BIAS, NULL, NULL
},
{
{"bgwriter_lru_percent", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer percentage of LRU buffers to flush per round"),
NULL
},
&bgwriter_lru_percent,
1.0, 0.0, 100.0, NULL, NULL
},
{
{"bgwriter_all_percent", PGC_SIGHUP, RESOURCES,
gettext_noop("Background writer percentage of all buffers to flush per round"),
NULL
},
&bgwriter_all_percent,
0.333, 0.0, 100.0, NULL, NULL
},
{
{"seed", PGC_USERSET, UNGROUPED,
gettext_noop("Sets the seed for random-number generation."),

6
src/backend/utils/misc/postgresql.conf.sample
View File

@@ -99,8 +99,10 @@
# - Background writer -
#bgwriter_delay = 200 # 10-10000 milliseconds between rounds
#bgwriter_percent = 1 # 0-100% of dirty buffers in each round
#bgwriter_maxpages = 100 # 0-1000 buffers max per round
#bgwriter_lru_percent = 1.0 # 0-100% of LRU buffers scanned in each round
#bgwriter_lru_maxpages = 5 # 0-1000 buffers max written per round
#bgwriter_all_percent = 0.333 # 0-100% of all buffers scanned in each round
#bgwriter_all_maxpages = 5 # 0-1000 buffers max written per round
#---------------------------------------------------------------------------

9
src/backend/utils/resowner/resowner.c
View File

@@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/resowner/resowner.c,v 1.9 2004/12/31 22:02:50 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/utils/resowner/resowner.c,v 1.10 2005/03/04 20:21:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -200,12 +200,7 @@ ResourceOwnerReleaseInternal(ResourceOwner owner,
* that would indicate failure to clean up the executor correctly ---
* so issue warnings. In the abort case, just clean up quietly.
*
* XXX this is fairly inefficient due to multiple BufMgrLock
* grabs if there are lots of buffers to be released, but we
* don't expect many (indeed none in the success case) so it's
* probably not worth optimizing.
*
* We are however careful to release back-to-front, so as to
* We are careful to do the releasing back-to-front, so as to
* avoid O(N^2) behavior in ResourceOwnerForgetBuffer().
*/
while (owner->nbuffers > 0)