From b284d8f29efc1c16c3aa75b64d9a940bcb74872c Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Tue, 3 Aug 2021 10:02:15 +1200 Subject: [PATCH v5 1/2] Optimize ProcSendSignal(). Instead of referring to target backends by pid, use pgprocno. This means that we don't have to scan the ProcArray, and we can drop some special case code for dealing with the startup process. In the case of buffer pin waits, we switch to storing the pgprocno of the waiter. In the case of SERIALIZABLE READ ONLY DEFERRABLE waits, we derive the pgprocno from the vxid (though that's not yet as efficient as it could be). Reviewed-by: Soumyadeep Chakraborty Reviewed-by: Ashwin Agrawal Discussion: https://postgr.es/m/CA%2BhUKGLYRyDaneEwz5Uya_OgFLMx5BgJfkQSD%3Dq9HmwsfRRb-w%40mail.gmail.com --- src/backend/access/transam/xlog.c | 3 -- src/backend/storage/buffer/buf_init.c | 3 +- src/backend/storage/buffer/bufmgr.c | 10 +++--- src/backend/storage/lmgr/predicate.c | 8 ++++- src/backend/storage/lmgr/proc.c | 49 ++------------------------- src/include/storage/buf_internals.h | 2 +- src/include/storage/proc.h | 6 +--- 7 files changed, 19 insertions(+), 62 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index f84c0bb01e..1574362724 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7308,9 +7308,6 @@ StartupXLOG(void) /* Also ensure XLogReceiptTime has a sane value */ XLogReceiptTime = GetCurrentTimestamp(); - /* Allow ProcSendSignal() to find us, for buffer pin wakeups. */ - PublishStartupProcessInformation(); - /* * Let postmaster know we've started redo now, so that it can launch * the archiver if necessary. diff --git a/src/backend/storage/buffer/buf_init.c b/src/backend/storage/buffer/buf_init.c index a299be1043..b9a83c0e9b 100644 --- a/src/backend/storage/buffer/buf_init.c +++ b/src/backend/storage/buffer/buf_init.c @@ -16,6 +16,7 @@ #include "storage/buf_internals.h" #include "storage/bufmgr.h" +#include "storage/proc.h" BufferDescPadded *BufferDescriptors; char *BufferBlocks; @@ -118,7 +119,7 @@ InitBufferPool(void) CLEAR_BUFFERTAG(buf->tag); pg_atomic_init_u32(&buf->state, 0); - buf->wait_backend_pid = 0; + buf->wait_backend_pgprocno = INVALID_PGPROCNO; buf->buf_id = i; diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index 33d99f604a..fb86c8706c 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -1890,11 +1890,11 @@ UnpinBuffer(BufferDesc *buf, bool fixOwner) BUF_STATE_GET_REFCOUNT(buf_state) == 1) { /* we just released the last pin other than the waiter's */ - int wait_backend_pid = buf->wait_backend_pid; + int wait_backend_pgprocno = buf->wait_backend_pgprocno; buf_state &= ~BM_PIN_COUNT_WAITER; UnlockBufHdr(buf, buf_state); - ProcSendSignal(wait_backend_pid); + ProcSendSignal(wait_backend_pgprocno); } else UnlockBufHdr(buf, buf_state); @@ -3995,7 +3995,7 @@ UnlockBuffers(void) * got a cancel/die interrupt before getting the signal. */ if ((buf_state & BM_PIN_COUNT_WAITER) != 0 && - buf->wait_backend_pid == MyProcPid) + buf->wait_backend_pgprocno == MyProc->pgprocno) buf_state &= ~BM_PIN_COUNT_WAITER; UnlockBufHdr(buf, buf_state); @@ -4131,7 +4131,7 @@ LockBufferForCleanup(Buffer buffer) LockBuffer(buffer, BUFFER_LOCK_UNLOCK); elog(ERROR, "multiple backends attempting to wait for pincount 1"); } - bufHdr->wait_backend_pid = MyProcPid; + bufHdr->wait_backend_pgprocno = MyProc->pgprocno; PinCountWaitBuf = bufHdr; buf_state |= BM_PIN_COUNT_WAITER; UnlockBufHdr(bufHdr, buf_state); @@ -4202,7 +4202,7 @@ LockBufferForCleanup(Buffer buffer) */ buf_state = LockBufHdr(bufHdr); if ((buf_state & BM_PIN_COUNT_WAITER) != 0 && - bufHdr->wait_backend_pid == MyProcPid) + bufHdr->wait_backend_pgprocno == MyProc->pgprocno) buf_state &= ~BM_PIN_COUNT_WAITER; UnlockBufHdr(bufHdr, buf_state); diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index 56267bdc3c..fbc0caca5c 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -207,6 +207,7 @@ #include "storage/predicate_internals.h" #include "storage/proc.h" #include "storage/procarray.h" +#include "storage/sinvaladt.h" #include "utils/rel.h" #include "utils/snapmgr.h" @@ -3669,7 +3670,12 @@ ReleasePredicateLocks(bool isCommit, bool isReadOnlySafe) */ if (SxactIsDeferrableWaiting(roXact) && (SxactIsROUnsafe(roXact) || SxactIsROSafe(roXact))) - ProcSendSignal(roXact->pid); + { + PGPROC *proc; + + proc = BackendIdGetProc(roXact->vxid.backendId); + ProcSendSignal(proc->pgprocno); + } possibleUnsafeConflict = nextConflict; } diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index b7d9da0aa9..7f2111c6e0 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -177,8 +177,6 @@ InitProcGlobal(void) ProcGlobal->autovacFreeProcs = NULL; ProcGlobal->bgworkerFreeProcs = NULL; ProcGlobal->walsenderFreeProcs = NULL; - ProcGlobal->startupProc = NULL; - ProcGlobal->startupProcPid = 0; ProcGlobal->startupBufferPinWaitBufId = -1; ProcGlobal->walwriterLatch = NULL; ProcGlobal->checkpointerLatch = NULL; @@ -624,21 +622,6 @@ InitAuxiliaryProcess(void) on_shmem_exit(AuxiliaryProcKill, Int32GetDatum(proctype)); } -/* - * Record the PID and PGPROC structures for the Startup process, for use in - * ProcSendSignal(). See comments there for further explanation. - */ -void -PublishStartupProcessInformation(void) -{ - SpinLockAcquire(ProcStructLock); - - ProcGlobal->startupProc = MyProc; - ProcGlobal->startupProcPid = MyProcPid; - - SpinLockRelease(ProcStructLock); -} - /* * Used from bufmgr to share the value of the buffer that Startup waits on, * or to reset the value to "not waiting" (-1). This allows processing @@ -1903,38 +1886,12 @@ ProcWaitForSignal(uint32 wait_event_info) } /* - * ProcSendSignal - send a signal to a backend identified by PID + * ProcSendSignal - send a signal to a backend identified by pgprocno */ void -ProcSendSignal(int pid) +ProcSendSignal(int pgprocno) { - PGPROC *proc = NULL; - - if (RecoveryInProgress()) - { - SpinLockAcquire(ProcStructLock); - - /* - * Check to see whether it is the Startup process we wish to signal. - * This call is made by the buffer manager when it wishes to wake up a - * process that has been waiting for a pin in so it can obtain a - * cleanup lock using LockBufferForCleanup(). Startup is not a normal - * backend, so BackendPidGetProc() will not return any pid at all. So - * we remember the information for this special case. - */ - if (pid == ProcGlobal->startupProcPid) - proc = ProcGlobal->startupProc; - - SpinLockRelease(ProcStructLock); - } - - if (proc == NULL) - proc = BackendPidGetProc(pid); - - if (proc != NULL) - { - SetLatch(&proc->procLatch); - } + SetLatch(&ProcGlobal->allProcs[pgprocno].procLatch); } /* diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h index 33fcaf5c9a..9b634616e4 100644 --- a/src/include/storage/buf_internals.h +++ b/src/include/storage/buf_internals.h @@ -187,7 +187,7 @@ typedef struct BufferDesc /* state of the tag, containing flags, refcount and usagecount */ pg_atomic_uint32 state; - int wait_backend_pid; /* backend PID of pin-count waiter */ + int wait_backend_pgprocno; /* backend of pin-count waiter */ int freeNext; /* link in freelist chain */ LWLock content_lock; /* to lock access to buffer contents */ } BufferDesc; diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h index be67d8a861..7c1e2efe30 100644 --- a/src/include/storage/proc.h +++ b/src/include/storage/proc.h @@ -352,9 +352,6 @@ typedef struct PROC_HDR Latch *checkpointerLatch; /* Current shared estimate of appropriate spins_per_delay value */ int spins_per_delay; - /* The proc of the Startup process, since not in ProcArray */ - PGPROC *startupProc; - int startupProcPid; /* Buffer id of the buffer that Startup process waits for pin on, or -1 */ int startupBufferPinWaitBufId; } PROC_HDR; @@ -395,7 +392,6 @@ extern void InitProcess(void); extern void InitProcessPhase2(void); extern void InitAuxiliaryProcess(void); -extern void PublishStartupProcessInformation(void); extern void SetStartupBufferPinWaitBufId(int bufid); extern int GetStartupBufferPinWaitBufId(void); @@ -411,7 +407,7 @@ extern bool IsWaitingForLock(void); extern void LockErrorCleanup(void); extern void ProcWaitForSignal(uint32 wait_event_info); -extern void ProcSendSignal(int pid); +extern void ProcSendSignal(int pgprocno); extern PGPROC *AuxiliaryPidGetProc(int pid); -- 2.30.2