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New GUC, track_iotiming, to track I/O timings.

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Currently, the only way to see the numbers this gathers is via
EXPLAIN (ANALYZE, BUFFERS), but the plan is to add visibility through
the stats collector and pg_stat_statements in subsequent patches.

Ants Aasma, reviewed by Greg Smith, with some further changes by me.
This commit is contained in:
Robert Haas
2012-03-27 14:52:37 -04:00
parent 98316e211b
commit 40b9b95769
8 changed files with 72 additions and 0 deletions
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24
src/backend/storage/buffer/bufmgr.c
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@ -67,6 +67,7 @@
bool zero_damaged_pages = false;
int bgwriter_lru_maxpages = 100;
double bgwriter_lru_multiplier = 2.0;
bool track_iotiming = false;
/*
* How many buffers PrefetchBuffer callers should try to stay ahead of their
@ -437,8 +438,21 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
MemSet((char *) bufBlock, 0, BLCKSZ);
else
{
instr_time io_start,
io_time;
if (track_iotiming)
INSTR_TIME_SET_CURRENT(io_start);
smgrread(smgr, forkNum, blockNum, (char *) bufBlock);
if (track_iotiming)
{
INSTR_TIME_SET_CURRENT(io_time);
INSTR_TIME_SUBTRACT(io_time, io_start);
INSTR_TIME_ADD(pgBufferUsage.time_read, io_time);
}
/* check for garbage data */
if (!PageHeaderIsValid((PageHeader) bufBlock))
{
@ -1874,6 +1888,7 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
{
XLogRecPtr recptr;
ErrorContextCallback errcontext;
instr_time io_start, io_end;
/*
* Acquire the buffer's io_in_progress lock. If StartBufferIO returns
@ -1921,12 +1936,21 @@ FlushBuffer(volatile BufferDesc *buf, SMgrRelation reln)
buf->flags &= ~BM_JUST_DIRTIED;
UnlockBufHdr(buf);
if (track_iotiming)
INSTR_TIME_SET_CURRENT(io_start);
smgrwrite(reln,
buf->tag.forkNum,
buf->tag.blockNum,
(char *) BufHdrGetBlock(buf),
false);
if (track_iotiming)
{
INSTR_TIME_SET_CURRENT(io_end);
INSTR_TIME_ACCUM_DIFF(pgBufferUsage.time_write, io_end, io_start);
}
pgBufferUsage.shared_blks_written++;
/*