From dc6d4049599031a17c94a10a5d0b1d666dfc3817 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 28 May 1999 17:03:31 +0000
Subject: [PATCH] Repair performance problem in SI segment manipulations:
iterating through MAXBACKENDS array entries used to be fine when MAXBACKENDS
= 64. It's not so cool with MAXBACKENDS = 1024 (or more!), especially not in
a frequently-used routine like SIDelExpiredDataEntries. Repair by making
procState array size be the soft MaxBackends limit rather than the hard
limit, and by converting SIGetProcStateLimit() to a macro.
---
src/backend/storage/ipc/ipci.c | 4 +-
src/backend/storage/ipc/sinval.c | 13 +++--
src/backend/storage/ipc/sinvaladt.c | 88 ++++++++++++-----------------
src/include/storage/sinval.h | 4 +-
src/include/storage/sinvaladt.h | 26 +++++----
5 files changed, 62 insertions(+), 73 deletions(-)
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 6fedbcf85af..fd0b53d9a61 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.24 1999/05/25 16:11:09 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.25 1999/05/28 17:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -108,7 +108,7 @@ CreateSharedMemoryAndSemaphores(IPCKey key, int maxBackends)
*/
InitProcGlobal(key, maxBackends);
- CreateSharedInvalidationState(key);
+ CreateSharedInvalidationState(key, maxBackends);
}
diff --git a/src/backend/storage/ipc/sinval.c b/src/backend/storage/ipc/sinval.c
index 3617fa345d7..220607ac050 100644
--- a/src/backend/storage/ipc/sinval.c
+++ b/src/backend/storage/ipc/sinval.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.14 1999/05/25 16:11:12 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.15 1999/05/28 17:03:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -31,12 +31,12 @@ extern BackendTag MyBackendTag;
SPINLOCK SInvalLock = (SPINLOCK) NULL;
/****************************************************************************/
-/* CreateSharedInvalidationState(key) Create a buffer segment */
+/* CreateSharedInvalidationState() Create a buffer segment */
/* */
/* should be called only by the POSTMASTER */
/****************************************************************************/
void
-CreateSharedInvalidationState(IPCKey key)
+CreateSharedInvalidationState(IPCKey key, int maxBackends)
{
int status;
@@ -46,7 +46,8 @@ CreateSharedInvalidationState(IPCKey key)
*/
/* SInvalLock gets set in spin.c, during spinlock init */
- status = SISegmentInit(true, IPCKeyGetSIBufferMemoryBlock(key));
+ status = SISegmentInit(true, IPCKeyGetSIBufferMemoryBlock(key),
+ maxBackends);
if (status == -1)
elog(FATAL, "CreateSharedInvalidationState: failed segment init");
@@ -64,11 +65,11 @@ AttachSharedInvalidationState(IPCKey key)
if (key == PrivateIPCKey)
{
- CreateSharedInvalidationState(key);
+ CreateSharedInvalidationState(key, 16);
return;
}
/* SInvalLock gets set in spin.c, during spinlock init */
- status = SISegmentInit(false, IPCKeyGetSIBufferMemoryBlock(key));
+ status = SISegmentInit(false, IPCKeyGetSIBufferMemoryBlock(key), 0);
if (status == -1)
elog(FATAL, "AttachSharedInvalidationState: failed segment init");
diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c
index 27393c63ef6..2ebda765a88 100644
--- a/src/backend/storage/ipc/sinvaladt.c
+++ b/src/backend/storage/ipc/sinvaladt.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.19 1999/05/25 16:11:13 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.20 1999/05/28 17:03:28 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -21,6 +21,7 @@
#include "storage/backendid.h"
#include "storage/sinvaladt.h"
#include "storage/lmgr.h"
+#include "utils/memutils.h"
#include "utils/palloc.h"
#include "utils/trace.h"
@@ -115,11 +116,9 @@ static BackendId
SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag)
{
Index index;
- ProcState *stateP;
+ ProcState *stateP = NULL;
- stateP = NULL;
-
- for (index = 0; index < MAXBACKENDS; index++)
+ for (index = 0; index < segInOutP->maxBackends; index++)
{
if (segInOutP->procState[index].tag == InvalidBackendTag ||
segInOutP->procState[index].tag == backendTag)
@@ -141,7 +140,7 @@ SIAssignBackendId(SISeg *segInOutP, BackendTag backendTag)
/* verify that all "procState" entries checked for matching tags */
- for (index++; index < MAXBACKENDS; index++)
+ for (index++; index < segInOutP->maxBackends; index++)
{
if (segInOutP->procState[index].tag == backendTag)
elog(FATAL, "SIAssignBackendId: tag %d found twice", backendTag);
@@ -201,30 +200,29 @@ CleanupInvalidationState(int status, /* XXX */
/************************************************************************/
-/* SIComputeSize() - retuns the size of a buffer segment */
+/* SIComputeSize() - compute size and offsets for SI segment */
/************************************************************************/
-static SISegOffsets *
-SIComputeSize(int *segSize)
+static void
+SIComputeSize(SISegOffsets *oP, int maxBackends)
{
int A,
B,
a,
b,
totalSize;
- SISegOffsets *oP;
A = 0;
- a = SizeSISeg; /* offset to first data entry */
- b = SizeOfOneSISegEntry * MAXNUMMESSAGES;
+ /* sizeof(SISeg) includes the first ProcState entry */
+ a = sizeof(SISeg) + sizeof(ProcState) * (maxBackends - 1);
+ a = MAXALIGN(a); /* offset to first data entry */
+ b = sizeof(SISegEntry) * MAXNUMMESSAGES;
B = A + a + b;
+ B = MAXALIGN(B);
totalSize = B - A;
- *segSize = totalSize;
- oP = (SISegOffsets *) palloc(sizeof(SISegOffsets));
oP->startSegment = A;
- oP->offsetToFirstEntry = a; /* relatiove to A */
- oP->offsetToEndOfSegemnt = totalSize; /* relative to A */
- return oP;
+ oP->offsetToFirstEntry = a; /* relative to A */
+ oP->offsetToEndOfSegment = totalSize; /* relative to A */
}
@@ -340,11 +338,9 @@ SISetMaxNumEntries(SISeg *segP, int num)
/************************************************************************/
/* SIGetProcStateLimit(segP, i) returns the limit of read messages */
/************************************************************************/
-static int
-SIGetProcStateLimit(SISeg *segP, int i)
-{
- return segP->procState[i].limit;
-}
+
+#define SIGetProcStateLimit(segP,i) \
+ ((segP)->procState[i].limit)
/************************************************************************/
/* SIIncNumEntries(segP, num) increments the current nuber of entries */
@@ -557,7 +553,7 @@ SIDecProcLimit(SISeg *segP, int num)
{
int i;
- for (i = 0; i < MAXBACKENDS; i++)
+ for (i = 0; i < segP->maxBackends; i++)
{
/* decrement only, if there is a limit > 0 */
if (segP->procState[i].limit > 0)
@@ -614,7 +610,7 @@ SISetProcStateInvalid(SISeg *segP)
{
int i;
- for (i = 0; i < MAXBACKENDS; i++)
+ for (i = 0; i < segP->maxBackends; i++)
{
if (segP->procState[i].limit == 0)
{
@@ -688,7 +684,7 @@ SIDelExpiredDataEntries(SISeg *segP)
h;
min = 9999999;
- for (i = 0; i < MAXBACKENDS; i++)
+ for (i = 0; i < segP->maxBackends; i++)
{
h = SIGetProcStateLimit(segP, i);
if (h >= 0)
@@ -715,24 +711,22 @@ SIDelExpiredDataEntries(SISeg *segP)
/* SISegInit(segP) - initializes the segment */
/************************************************************************/
static void
-SISegInit(SISeg *segP)
+SISegInit(SISeg *segP, SISegOffsets *oP, int maxBackends)
{
- SISegOffsets *oP;
- int segSize,
- i;
+ int i;
SISegEntry *eP;
- oP = SIComputeSize(&segSize);
- /* set sempahore ids in the segment */
+ /* set semaphore ids in the segment */
/* XXX */
SISetStartEntrySection(segP, oP->offsetToFirstEntry);
- SISetEndEntrySection(segP, oP->offsetToEndOfSegemnt);
+ SISetEndEntrySection(segP, oP->offsetToEndOfSegment);
SISetStartFreeSpace(segP, 0);
SISetStartEntryChain(segP, InvalidOffset);
SISetEndEntryChain(segP, InvalidOffset);
SISetNumEntries(segP, 0);
SISetMaxNumEntries(segP, MAXNUMMESSAGES);
- for (i = 0; i < MAXBACKENDS; i++)
+ segP->maxBackends = maxBackends;
+ for (i = 0; i < segP->maxBackends; i++)
{
segP->procState[i].limit = -1; /* no backend active !! */
segP->procState[i].resetState = false;
@@ -753,12 +747,6 @@ SISegInit(SISeg *segP)
(MAXNUMMESSAGES - 1) * sizeof(SISegEntry));
eP->isfree = true;
eP->next = InvalidOffset; /* it's the end of the chain !! */
-
- /*
- * Be tidy
- */
- pfree(oP);
-
}
@@ -808,13 +796,14 @@ SISegmentAttach(IpcMemoryId shmid)
/************************************************************************/
-/* SISegmentInit(killExistingSegment, key) initialize segment */
+/* SISegmentInit() initialize SI segment */
+/* */
+/* NB: maxBackends param is only valid when killExistingSegment is true */
/************************************************************************/
int
-SISegmentInit(bool killExistingSegment, IPCKey key)
+SISegmentInit(bool killExistingSegment, IPCKey key, int maxBackends)
{
- SISegOffsets *oP;
- int segSize;
+ SISegOffsets offsets;
IpcMemoryId shmId;
bool create;
@@ -825,16 +814,9 @@ SISegmentInit(bool killExistingSegment, IPCKey key)
SISegmentKill(key);
/* Get a shared segment */
-
- oP = SIComputeSize(&segSize);
-
- /*
- * Be tidy
- */
- pfree(oP);
-
+ SIComputeSize(&offsets, maxBackends);
create = true;
- shmId = SISegmentGet(key, segSize, create);
+ shmId = SISegmentGet(key, offsets.offsetToEndOfSegment, create);
if (shmId < 0)
{
perror("SISegmentGet: failed");
@@ -846,7 +828,7 @@ SISegmentInit(bool killExistingSegment, IPCKey key)
SISegmentAttach(shmId);
/* Init shared memory table */
- SISegInit(shmInvalBuffer);
+ SISegInit(shmInvalBuffer, &offsets, maxBackends);
}
else
{
diff --git a/src/include/storage/sinval.h b/src/include/storage/sinval.h
index c5af7b08c98..8ef86c8a488 100644
--- a/src/include/storage/sinval.h
+++ b/src/include/storage/sinval.h
@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
- * $Id: sinval.h,v 1.10 1999/02/13 23:22:10 momjian Exp $
+ * $Id: sinval.h,v 1.11 1999/05/28 17:03:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -18,7 +18,7 @@
extern SPINLOCK SInvalLock;
-extern void CreateSharedInvalidationState(IPCKey key);
+extern void CreateSharedInvalidationState(IPCKey key, int maxBackends);
extern void AttachSharedInvalidationState(IPCKey key);
extern void InitSharedInvalidationState(void);
extern void RegisterSharedInvalid(int cacheId, Index hashIndex,
diff --git a/src/include/storage/sinvaladt.h b/src/include/storage/sinvaladt.h
index d92969a85b0..c939a0c6dbe 100644
--- a/src/include/storage/sinvaladt.h
+++ b/src/include/storage/sinvaladt.h
@@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
- * $Id: sinvaladt.h,v 1.13 1999/05/25 16:14:46 momjian Exp $
+ * $Id: sinvaladt.h,v 1.14 1999/05/28 17:03:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -31,7 +31,8 @@ A------------- Header info --------------
endEntryChain (offset relative to B)
numEntries
maxNumEntries
- procState[MAXBACKENDS] --> limit
+ maxBackends
+ procState[maxBackends] --> limit
resetState (bool)
a tag (POSTID)
B------------- Start entry section -------
@@ -70,12 +71,18 @@ typedef struct SISeg
Offset endEntryChain; /* (offset relative to B) */
int numEntries;
int maxNumEntries;
- ProcState procState[MAXBACKENDS]; /* reflects the invalidation state */
- /* here starts the entry section, controlled by offsets */
+ int maxBackends; /* size of procState array */
+ /*
+ * We declare procState as 1 entry because C wants a fixed-size array,
+ * but actually it is maxBackends entries long.
+ */
+ ProcState procState[1]; /* reflects the invalidation state */
+ /*
+ * The entry section begins after the end of the procState array.
+ * Everything there is controlled by offsets.
+ */
} SISeg;
-#define SizeSISeg sizeof(SISeg)
-
typedef struct SharedInvalidData
{
int cacheId; /* XXX */
@@ -93,13 +100,11 @@ typedef struct SISegEntry
Offset next; /* offset to next entry */
} SISegEntry;
-#define SizeOfOneSISegEntry sizeof(SISegEntry)
-
typedef struct SISegOffsets
{
Offset startSegment; /* always 0 (for now) */
Offset offsetToFirstEntry; /* A + a = B */
- Offset offsetToEndOfSegemnt; /* A + a + b */
+ Offset offsetToEndOfSegment; /* A + a + b */
} SISegOffsets;
@@ -118,7 +123,8 @@ extern SISeg *shmInvalBuffer;
* prototypes for functions in sinvaladt.c
*/
extern int SIBackendInit(SISeg *segInOutP);
-extern int SISegmentInit(bool killExistingSegment, IPCKey key);
+extern int SISegmentInit(bool killExistingSegment, IPCKey key,
+ int maxBackends);
extern bool SISetDataEntry(SISeg *segP, SharedInvalidData *data);
extern void SISetProcStateInvalid(SISeg *segP);
--
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