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Specialize checkpointer sort functions. 

When sorting a potentially large number of dirty buffers, the
checkpointer can benefit from a faster sort routine.  One reported
improvement on a large buffer pool system was 1.4s -> 0.6s.

Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CA%2BhUKGJ2-eaDqAum5bxhpMNhvuJmRDZxB_Tow0n-gse%2BHG0Yig%40mail.gmail.com
This commit is contained in:
Thomas Munro 2021-03-12 23:56:02 +13:00
parent 519e4c9ee2
commit 1b88b8908e
1 changed files with 22 additions and 15 deletions
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37
src/backend/storage/buffer/bufmgr.c
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@ -488,8 +488,8 @@ static void FindAndDropRelFileNodeBuffers(RelFileNode rnode,
static void AtProcExit_Buffers(int code, Datum arg);
static void CheckForBufferLeaks(void);
static int rnode_comparator(const void *p1, const void *p2);
static int buffertag_comparator(const void *p1, const void *p2);
static int ckpt_buforder_comparator(const void *pa, const void *pb);
static inline int buffertag_comparator(const BufferTag *a, const BufferTag *b);
static inline int ckpt_buforder_comparator(const CkptSortItem *a, const CkptSortItem *b);
static int ts_ckpt_progress_comparator(Datum a, Datum b, void *arg);
@ -1831,6 +1831,13 @@ UnpinBuffer(BufferDesc *buf, bool fixOwner)
}
}
#define ST_SORT sort_checkpoint_bufferids
#define ST_ELEMENT_TYPE CkptSortItem
#define ST_COMPARE(a, b) ckpt_buforder_comparator(a, b)
#define ST_SCOPE static
#define ST_DEFINE
#include <lib/sort_template.h>
/*
* BufferSync -- Write out all dirty buffers in the pool.
*
@ -1931,8 +1938,7 @@ BufferSync(int flags)
* end up writing to the tablespaces one-by-one; possibly overloading the
* underlying system.
*/
qsort(CkptBufferIds, num_to_scan, sizeof(CkptSortItem),
ckpt_buforder_comparator);
sort_checkpoint_bufferids(CkptBufferIds, num_to_scan);
num_spaces = 0;
@ -4567,11 +4573,9 @@ WaitBufHdrUnlocked(BufferDesc *buf)
/*
* BufferTag comparator.
*/
static int
buffertag_comparator(const void *a, const void *b)
static inline int
buffertag_comparator(const BufferTag *ba, const BufferTag *bb)
{
const BufferTag *ba = (const BufferTag *) a;
const BufferTag *bb = (const BufferTag *) b;
int ret;
ret = rnode_comparator(&ba->rnode, &bb->rnode);
@ -4598,12 +4602,9 @@ buffertag_comparator(const void *a, const void *b)
* It is important that tablespaces are compared first, the logic balancing
* writes between tablespaces relies on it.
*/
static int
ckpt_buforder_comparator(const void *pa, const void *pb)
static inline int
ckpt_buforder_comparator(const CkptSortItem *a, const CkptSortItem *b)
{
const CkptSortItem *a = (const CkptSortItem *) pa;
const CkptSortItem *b = (const CkptSortItem *) pb;
/* compare tablespace */
if (a->tsId < b->tsId)
return -1;
@ -4694,6 +4695,13 @@ ScheduleBufferTagForWriteback(WritebackContext *context, BufferTag *tag)
IssuePendingWritebacks(context);
}
#define ST_SORT sort_pending_writebacks
#define ST_ELEMENT_TYPE PendingWriteback
#define ST_COMPARE(a, b) buffertag_comparator(&a->tag, &b->tag)
#define ST_SCOPE static
#define ST_DEFINE
#include <lib/sort_template.h>
/*
* Issue all pending writeback requests, previously scheduled with
* ScheduleBufferTagForWriteback, to the OS.
@ -4713,8 +4721,7 @@ IssuePendingWritebacks(WritebackContext *context)
* Executing the writes in-order can make them a lot faster, and allows to
* merge writeback requests to consecutive blocks into larger writebacks.
*/
qsort(&context->pending_writebacks, context->nr_pending,
sizeof(PendingWriteback), buffertag_comparator);
sort_pending_writebacks(context->pending_writebacks, context->nr_pending);
/*
* Coalesce neighbouring writes, but nothing else. For that we iterate