On 11/06/2015 08:53 PM, Robert Haas wrote:
On Fri, Nov 6, 2015 at 6:27 AM, Ildus Kurbangaliev
<i.kurbangal...@postgrespro.ru> wrote:
There is a patch that splits SLRU LWLocks to separate tranches and
moves them to SLRU Ctl. It does some work from the main patch from
this thread, but can be commited separately. It also simplifies
lwlock.c.
Thanks. I like the direction this is going.
- char *ptr;
- Size offset;
- int slotno;
+ char *ptr;
+ Size offset;
+ int slotno;
+ int tranche_id;
+ LWLockPadded *locks;
Please don't introduce this kind of churn. pgindent will undo it.
This isn't going to work for EXEC_BACKEND builds, I think. It seems
to rely on the LWLockRegisterTranche() performed !IsUnderPostmaster
being inherited by subsequent children, which won't work under
EXEC_BACKEND. Instead, store the tranche ID in SlruSharedData. Move
the LWLockRegisterTranche call out from the (!IsUnderPostmaster) case
and call it based on the tranche ID from SlruSharedData.
I would just drop the add_postfix stuff. I think it's fine if the
names of the shared memory checks are just "CLOG" etc. rather than
"CLOG Slru Ctl", and similarly I think the locks can be registered
without the "Locks" suffix. It'll be clear from context that they are
locks. I suggest also that we just change all of these names to be
lower case, though I realize that's a debatable and cosmetic point.
Thanks for the review. I've attached a new version of SLRU patch. I've
removed
add_postfix and fixed EXEC_BACKEND case.
--
Ildus Kurbangaliev
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index 3a58f1e..ea83655 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -456,7 +456,7 @@ void
CLOGShmemInit(void)
{
ClogCtl->PagePrecedes = CLOGPagePrecedes;
- SimpleLruInit(ClogCtl, "CLOG Ctl", CLOGShmemBuffers(), CLOG_LSNS_PER_PAGE,
+ SimpleLruInit(ClogCtl, "clog", CLOGShmemBuffers(), CLOG_LSNS_PER_PAGE,
CLogControlLock, "pg_clog");
}
diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.c
index b21a313..d2c281f 100644
--- a/src/backend/access/transam/commit_ts.c
+++ b/src/backend/access/transam/commit_ts.c
@@ -478,7 +478,7 @@ CommitTsShmemInit(void)
bool found;
CommitTsCtl->PagePrecedes = CommitTsPagePrecedes;
- SimpleLruInit(CommitTsCtl, "CommitTs Ctl", CommitTsShmemBuffers(), 0,
+ SimpleLruInit(CommitTsCtl, "committs", CommitTsShmemBuffers(), 0,
CommitTsControlLock, "pg_commit_ts");
commitTsShared = ShmemInitStruct("CommitTs shared",
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 7d97085..b66a2b6 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -1838,10 +1838,10 @@ MultiXactShmemInit(void)
MultiXactMemberCtl->PagePrecedes = MultiXactMemberPagePrecedes;
SimpleLruInit(MultiXactOffsetCtl,
- "MultiXactOffset Ctl", NUM_MXACTOFFSET_BUFFERS, 0,
+ "multixact_offset", NUM_MXACTOFFSET_BUFFERS, 0,
MultiXactOffsetControlLock, "pg_multixact/offsets");
SimpleLruInit(MultiXactMemberCtl,
- "MultiXactMember Ctl", NUM_MXACTMEMBER_BUFFERS, 0,
+ "multixact_member", NUM_MXACTMEMBER_BUFFERS, 0,
MultiXactMemberControlLock, "pg_multixact/members");
/* Initialize our shared state struct */
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index 90c7cf5..868b35a 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -157,6 +157,8 @@ SimpleLruShmemSize(int nslots, int nlsns)
if (nlsns > 0)
sz += MAXALIGN(nslots * nlsns * sizeof(XLogRecPtr)); /* group_lsn[] */
+ sz += MAXALIGN(nslots * sizeof(LWLockPadded)); /* lwlocks[] */
+
return BUFFERALIGN(sz) + BLCKSZ * nslots;
}
@@ -174,9 +176,10 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
if (!IsUnderPostmaster)
{
/* Initialize locks and shared memory area */
- char *ptr;
- Size offset;
- int slotno;
+ char *ptr;
+ Size offset;
+ int slotno;
+ LWLockPadded *locks;
Assert(!found);
@@ -212,6 +215,17 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
offset += MAXALIGN(nslots * nlsns * sizeof(XLogRecPtr));
}
+ /* Initialize LWLocks */
+ locks = (LWLockPadded *) ShmemAlloc(sizeof(LWLockPadded) * nslots);
+
+ shared->locks_tranche_id = LWLockNewTrancheId();
+ shared->locks_tranche.name = pstrdup(name);
+ shared->locks_tranche.array_base = locks;
+ shared->locks_tranche.array_stride = sizeof(LWLockPadded);
+
+ for (slotno = 0; slotno < nslots; slotno++)
+ LWLockInitialize(&locks[slotno].lock, shared->locks_tranche_id);
+
ptr += BUFFERALIGN(offset);
for (slotno = 0; slotno < nslots; slotno++)
{
@@ -219,13 +233,16 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
shared->page_status[slotno] = SLRU_PAGE_EMPTY;
shared->page_dirty[slotno] = false;
shared->page_lru_count[slotno] = 0;
- shared->buffer_locks[slotno] = LWLockAssign();
+ shared->buffer_locks[slotno] = &locks[slotno].lock;
ptr += BLCKSZ;
}
}
else
Assert(found);
+ /* Register SLRU tranche in the main tranches array */
+ LWLockRegisterTranche(shared->locks_tranche_id, &shared->locks_tranche);
+
/*
* Initialize the unshared control struct, including directory path. We
* assume caller set PagePrecedes.
diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c
index 6b70982..36426c5 100644
--- a/src/backend/access/transam/subtrans.c
+++ b/src/backend/access/transam/subtrans.c
@@ -178,7 +178,7 @@ void
SUBTRANSShmemInit(void)
{
SubTransCtl->PagePrecedes = SubTransPagePrecedes;
- SimpleLruInit(SubTransCtl, "SUBTRANS Ctl", NUM_SUBTRANS_BUFFERS, 0,
+ SimpleLruInit(SubTransCtl, "subtrans", NUM_SUBTRANS_BUFFERS, 0,
SubtransControlLock, "pg_subtrans");
/* Override default assumption that writes should be fsync'd */
SubTransCtl->do_fsync = false;
diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c
index 5059e3d..38231c9 100644
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -479,7 +479,7 @@ AsyncShmemInit(void)
* Set up SLRU management of the pg_notify data.
*/
AsyncCtl->PagePrecedes = asyncQueuePagePrecedes;
- SimpleLruInit(AsyncCtl, "Async Ctl", NUM_ASYNC_BUFFERS, 0,
+ SimpleLruInit(AsyncCtl, "async", NUM_ASYNC_BUFFERS, 0,
AsyncCtlLock, "pg_notify");
/* Override default assumption that writes should be fsync'd */
AsyncCtl->do_fsync = false;
diff --git a/src/backend/storage/lmgr/lwlock.c b/src/backend/storage/lmgr/lwlock.c
index fd4b479..6bca02c 100644
--- a/src/backend/storage/lmgr/lwlock.c
+++ b/src/backend/storage/lmgr/lwlock.c
@@ -76,11 +76,6 @@
*/
#include "postgres.h"
-#include "access/clog.h"
-#include "access/commit_ts.h"
-#include "access/multixact.h"
-#include "access/subtrans.h"
-#include "commands/async.h"
#include "miscadmin.h"
#include "pg_trace.h"
#include "postmaster/postmaster.h"
@@ -364,24 +359,6 @@ NumLWLocks(void)
/* proc.c needs one for each backend or auxiliary process */
numLocks += MaxBackends + NUM_AUXILIARY_PROCS;
- /* clog.c needs one per CLOG buffer */
- numLocks += CLOGShmemBuffers();
-
- /* commit_ts.c needs one per CommitTs buffer */
- numLocks += CommitTsShmemBuffers();
-
- /* subtrans.c needs one per SubTrans buffer */
- numLocks += NUM_SUBTRANS_BUFFERS;
-
- /* multixact.c needs two SLRU areas */
- numLocks += NUM_MXACTOFFSET_BUFFERS + NUM_MXACTMEMBER_BUFFERS;
-
- /* async.c needs one per Async buffer */
- numLocks += NUM_ASYNC_BUFFERS;
-
- /* predicate.c needs one per old serializable xid buffer */
- numLocks += NUM_OLDSERXID_BUFFERS;
-
/* slot.c needs one for each slot */
numLocks += max_replication_slots;
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index 47b4ada..4b4ad81 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -794,7 +794,7 @@ OldSerXidInit(void)
* Set up SLRU management of the pg_serial data.
*/
OldSerXidSlruCtl->PagePrecedes = OldSerXidPagePrecedesLogically;
- SimpleLruInit(OldSerXidSlruCtl, "OldSerXid SLRU Ctl",
+ SimpleLruInit(OldSerXidSlruCtl, "oldserxid",
NUM_OLDSERXID_BUFFERS, 0, OldSerXidLock, "pg_serial");
/* Override default assumption that writes should be fsync'd */
OldSerXidSlruCtl->do_fsync = false;
diff --git a/src/include/access/slru.h b/src/include/access/slru.h
index f60e75b..caf4fff 100644
--- a/src/include/access/slru.h
+++ b/src/include/access/slru.h
@@ -99,6 +99,10 @@ typedef struct SlruSharedData
* the latest page.
*/
int latest_page_number;
+
+ /* LWLocks */
+ int locks_tranche_id;
+ LWLockTranche locks_tranche;
} SlruSharedData;
typedef SlruSharedData *SlruShared;
--
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