On Wed, 23 Sep 2015 11:46:00 -0400
Robert Haas <robertmh...@gmail.com> wrote:
> On Wed, Sep 23, 2015 at 11:22 AM, Alvaro Herrera
> <alvhe...@2ndquadrant.com> wrote:
> > Robert Haas wrote:
> >> On Tue, Sep 22, 2015 at 5:16 AM, Ildus Kurbangaliev
> >> <i.kurbangal...@postgrespro.ru> wrote:
> >> > Yes, probably.
> >> > I'm going to change API calls as you suggested earlier.
> >> > How you do think the tranches registration after initialization
> >> > should look like?
> >>
> >> I don't see any need to change anything there. The idea there is
> >> that an extension allocates a tranche ID and are responsible for
> >> making sure that every backend that uses that tranche finds out
> >> about the ID that was chosen and registers a matching tranche
> >> definition. How to do that is the extension's problem. Maybe
> >> eventually we'll provide some tools to make that easier, but
> >> that's separate from the work we're trying to do here.
> >
> > FWIW I had assumed, when you created the tranche stuff, that SLRU
> > users would all allocate their lwlocks from a tranche provided by
> > slru.c itself, and the locks would be stored in the slru Ctl
> > struct. Does that not work for some reason?
>
> I think that should work and that it's a good idea. I think it's just
> a case of nobody having done the work.
>
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.
--
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..887efc9 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..3c8291c 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..1341c00 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,
+ "MultiXactOffset", NUM_MXACTOFFSET_BUFFERS, 0,
MultiXactOffsetControlLock, "pg_multixact/offsets");
SimpleLruInit(MultiXactMemberCtl,
- "MultiXactMember Ctl", NUM_MXACTMEMBER_BUFFERS, 0,
+ "MultiXactMember", 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..1eb9a25 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -136,6 +136,16 @@ static bool SlruScanDirCbDeleteCutoff(SlruCtl ctl, char *filename,
int segpage, void *data);
static void SlruInternalDeleteSegment(SlruCtl ctl, char *filename);
+/* Add a postfix to a some string */
+static char *
+add_postfix(const char *name, const char *postfix)
+{
+ int len = strlen(name) + strlen(postfix) + 1;
+ char *buf = (char *) palloc(len);
+ snprintf(buf, len, "%s%s", name, postfix);
+ return buf;
+}
+
/*
* Initialization of shared memory
*/
@@ -157,6 +167,8 @@ 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;
}
@@ -164,19 +176,23 @@ void
SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
LWLock *ctllock, const char *subdir)
{
- SlruShared shared;
- bool found;
+ SlruShared shared;
+ bool found;
+ char *shared_key = add_postfix(name, " SLRU Ctl");
- shared = (SlruShared) ShmemInitStruct(name,
+ shared = (SlruShared) ShmemInitStruct(shared_key,
SimpleLruShmemSize(nslots, nlsns),
&found);
+ pfree(shared_key);
if (!IsUnderPostmaster)
{
/* Initialize locks and shared memory area */
- char *ptr;
- Size offset;
- int slotno;
+ char *ptr;
+ Size offset;
+ int slotno;
+ int tranche_id;
+ LWLockPadded *locks;
Assert(!found);
@@ -212,6 +228,19 @@ 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.name = add_postfix(name, "Locks");
+ shared->locks_tranche.array_base = locks;
+ shared->locks_tranche.array_stride = sizeof(LWLockPadded);
+
+ tranche_id = LWLockNewTrancheId();
+ LWLockRegisterTranche(tranche_id, &shared->locks_tranche);
+
+ for (slotno = 0; slotno < nslots; slotno++)
+ LWLockInitialize(&locks[slotno].lock, tranche_id);
+
ptr += BUFFERALIGN(offset);
for (slotno = 0; slotno < nslots; slotno++)
{
@@ -219,7 +248,7 @@ 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;
}
}
diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c
index 6b70982..e0a2461 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..8a7e59e 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..7242687 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..4c68c28 100644
--- a/src/include/access/slru.h
+++ b/src/include/access/slru.h
@@ -99,6 +99,9 @@ typedef struct SlruSharedData
* the latest page.
*/
int latest_page_number;
+
+ /* LWLocks */
+ LWLockTranche locks_tranche;
} SlruSharedData;
typedef SlruSharedData *SlruShared;
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
