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[PATCH v3 4/6] Convert PROC_HDR->startupBufferPinWaitBuf to an atomic variable. 1+ messages / 1 participants [nested] [flat]
* [PATCH v3 4/6] Convert PROC_HDR->startupBufferPinWaitBuf to an atomic variable. @ 2026-09-08 17:40 Nathan Bossart <nathan@postgresql.org> 0 siblings, 0 replies; 1+ messages in thread From: Nathan Bossart @ 2026-09-08 17:40 UTC (permalink / raw) Currently, this variable is a Buffer that is accessed via a volatile pointer. By converting it to an atomic variable, we can remove the volatile qualifiers. No barriers are needed; as the comment there notes, the value is published before the backends that read it are signaled. --- src/backend/storage/lmgr/proc.c | 12 +++--------- src/include/storage/proc.h | 2 +- 2 files changed, 4 insertions(+), 10 deletions(-) diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index ab65a6dbcc9..91fe2766640 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -238,7 +238,7 @@ ProcGlobalShmemInit(void *arg) dlist_init(&ProcGlobal->autovacFreeProcs); dlist_init(&ProcGlobal->bgworkerFreeProcs); dlist_init(&ProcGlobal->walsenderFreeProcs); - ProcGlobal->startupBufferPinWaitBuf = InvalidBuffer; + pg_atomic_init_u32(&ProcGlobal->startupBufferPinWaitBuf, InvalidBuffer); pg_atomic_init_u32(&ProcGlobal->avLauncherProc, INVALID_PROC_NUMBER); pg_atomic_init_u32(&ProcGlobal->walwriterProc, INVALID_PROC_NUMBER); pg_atomic_init_u32(&ProcGlobal->checkpointerProc, INVALID_PROC_NUMBER); @@ -767,10 +767,7 @@ InitAuxiliaryProcess(void) void SetStartupBufferPinWaitBuf(Buffer buffer) { - /* use volatile pointer to prevent code rearrangement */ - volatile PROC_HDR *procglobal = ProcGlobal; - - procglobal->startupBufferPinWaitBuf = buffer; + pg_atomic_write_u32(&ProcGlobal->startupBufferPinWaitBuf, buffer); } /* @@ -779,10 +776,7 @@ SetStartupBufferPinWaitBuf(Buffer buffer) Buffer GetStartupBufferPinWaitBuf(void) { - /* use volatile pointer to prevent code rearrangement */ - volatile PROC_HDR *procglobal = ProcGlobal; - - return procglobal->startupBufferPinWaitBuf; + return pg_atomic_read_u32(&ProcGlobal->startupBufferPinWaitBuf); } /* diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h index 4c3f431b4eb..abe40001d9a 100644 --- a/src/include/storage/proc.h +++ b/src/include/storage/proc.h @@ -500,7 +500,7 @@ typedef struct PROC_HDR /* Current shared estimate of appropriate spins_per_delay value */ int spins_per_delay; /* Buffer that Startup process waits for pin on, or InvalidBuffer */ - Buffer startupBufferPinWaitBuf; + pg_atomic_uint32 startupBufferPinWaitBuf; } PROC_HDR; extern PGDLLIMPORT PROC_HDR *ProcGlobal; -- 2.55.0 --hwKv7DgSDwjNaYBK Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v3-0005-Convert-Sharedsort-s-worker-counters-to-atomic-va.patch ^ permalink raw reply [nested|flat] 1+ messages in thread
only message in thread Thread overview: 1+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2026-09-08 17:40 [PATCH v3 4/6] Convert PROC_HDR->startupBufferPinWaitBuf to an atomic variable. Nathan Bossart <nathan@postgresql.org>
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