database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-29 10:41:53 +03:00
Code Activity

Defer flushing of SLRU files.

Browse Source 
Previously, we called fsync() after writing out individual pg_xact,
pg_multixact and pg_commit_ts pages due to cache pressure, leading to
regular I/O stalls in user backends and recovery.  Collapse requests for
the same file into a single system call as part of the next checkpoint,
as we already did for relation files, using the infrastructure developed
by commit 3eb77eba.  This can cause a significant improvement to
recovery performance, especially when it's otherwise CPU-bound.

Hoist ProcessSyncRequests() up into CheckPointGuts() to make it clearer
that it applies to all the SLRU mini-buffer-pools as well as the main
buffer pool.  Rearrange things so that data collected in CheckpointStats
includes SLRU activity.

Also remove the Shutdown{CLOG,CommitTS,SUBTRANS,MultiXact}() functions,
because they were redundant after the shutdown checkpoint that
immediately precedes them.  (I'm not sure if they were ever needed, but
they aren't now.)

Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (parts)
Tested-by: Jakub Wartak <Jakub.Wartak@tomtom.com>
Discussion: https://postgr.es/m/CA+hUKGLJ=84YT+NvhkEEDAuUtVHMfQ9i-N7k_o50JmQ6Rpj_OQ@mail.gmail.com
This commit is contained in:
Thomas Munro
2020-09-25 18:49:43 +12:00
parent ca7f8e2b86
commit dee663f784
16 changed files with 255 additions and 175 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
src/backend/access/transam/xlog.c
View File

@ -8528,10 +8528,6 @@ ShutdownXLOG(int code, Datum arg)
CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE);
}
ShutdownCLOG();
ShutdownCommitTs();
ShutdownSUBTRANS();
ShutdownMultiXact();
}
/*
@ -9176,17 +9172,29 @@ CreateEndOfRecoveryRecord(void)
static void
CheckPointGuts(XLogRecPtr checkPointRedo, int flags)
{
CheckPointRelationMap();
CheckPointReplicationSlots();
CheckPointSnapBuild();
CheckPointLogicalRewriteHeap();
CheckPointReplicationOrigin();
/* Write out all dirty data in SLRUs and the main buffer pool */
TRACE_POSTGRESQL_BUFFER_CHECKPOINT_START(flags);
CheckpointStats.ckpt_write_t = GetCurrentTimestamp();
CheckPointCLOG();
CheckPointCommitTs();
CheckPointSUBTRANS();
CheckPointMultiXact();
CheckPointPredicate();
CheckPointRelationMap();
CheckPointReplicationSlots();
CheckPointSnapBuild();
CheckPointLogicalRewriteHeap();
CheckPointBuffers(flags); /* performs all required fsyncs */
CheckPointReplicationOrigin();
CheckPointBuffers(flags);
/* Perform all queued up fsyncs */
TRACE_POSTGRESQL_BUFFER_CHECKPOINT_SYNC_START();
CheckpointStats.ckpt_sync_t = GetCurrentTimestamp();
ProcessSyncRequests();
CheckpointStats.ckpt_sync_end_t = GetCurrentTimestamp();
TRACE_POSTGRESQL_BUFFER_CHECKPOINT_DONE();
/* We deliberately delay 2PC checkpointing as long as possible */
CheckPointTwoPhase(checkPointRedo);
}