v5 attached mostly addresses instr_time persistence issues.
On Tue, Mar 14, 2023 at 6:56 PM Andres Freund <and...@anarazel.de> wrote:
> On 2023-03-09 11:50:38 -0500, Melanie Plageman wrote:
> > On Tue, Mar 7, 2023 at 1:39 PM Andres Freund <and...@anarazel.de> wrote:
> > > On 2023-03-06 11:30:13 -0500, Melanie Plageman wrote:
> > > > > As pgstat_bktype_io_stats_valid() is called only in Assert(), I think
> > > > > that would be a good idea
> > > > > to also check that if counts are not Zero then times are not Zero.
> > > >
> > > > Yes, I think adding some validation around the relationship between
> > > > counts and timing should help prevent developers from forgetting to call
> > > > pg_stat_count_io_op() when calling pgstat_count_io_time() (as relevant).
> > > >
> > > > However, I think that we cannot check that if IO counts are non-zero
> > > > that IO times are non-zero, because the user may not have
> > > > track_io_timing enabled. We can check that if IO times are not zero, IO
> > > > counts are not zero. I've done this in the attached v3.
> > >
> > > And even if track_io_timing is enabled, the timer granularity might be so
> > > low
> > > that we *still* get zeroes.
> > >
> > > I wonder if we should get rid of pgStatBlockReadTime,
> > > pgStatBlockWriteTime,
> >
> > And then have pg_stat_reset_shared('io') reset pg_stat_database IO
> > stats?
>
> Yes.
I think this makes sense but I am hesitant to do it in this patchset,
because it feels a bit hidden...maybe?
But, if you feel strongly, I will make the change.
> > > > typedef struct PgStat_BktypeIO
> > > > {
> > > > - PgStat_Counter
> > > > data[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
> > > > + PgStat_Counter
> > > > counts[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
> > > > + instr_time
> > > > times[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
> > > > } PgStat_BktypeIO;
> > >
> > > Ah, you're going to hate me. We can't store instr_time on disk. There's
> > > another patch that gets substantial peformance gains by varying the
> > > frequency
> > > at which instr_time keeps track of time based on the CPU frequency...
> >
> > What does that have to do with what we can store on disk?
>
> The frequency can change.
Ah, I see.
> > If so, would it not be enough to do this when reading/writing the stats
> > file?
>
> Theoretically yes. But to me it seems cleaner to do it when flushing to shared
> stats. See also the overflow issue below.
>
> > > It also just doesn't have enough range to keep track of system wide
> > > time on a larger system. A single backend won't run for 293 years, but
> > > with a few thousand backends that's a whole different story.
> > >
> > > I think we need to accumulate in instr_time, but convert to floating point
> > > when flushing stats.
> >
> > Hmmm. So, are you saying that we need to read from disk when we query
> > the view and add that to what is in shared memory? That we only store
> > the delta since the last restart in the instr_time array?
>
> No, I don't think I am suggesting that. What I am trying to suggest is that
> PendingIOStats should contain instr_time, but that PgStat_IO should contain
> PgStat_Counter as microseconds, as before.
So, I've modified the code to make a union of instr_time and
PgStat_Counter in PgStat_BktypeIO. I am not quite sure if this is okay.
I store in microsec and then in pg_stat_io, I multiply to get
milliseconds for display.
I considered refactoring pgstat_io_end() to use INSTR_TIME_ACCUM_DIFF()
like [1], but, in the end I actually think I would end up with more
operations because of the various different counters needing to be
updated. As it is now, I do a single subtract and a few adds (one for
each of the different statistics objects tracking IO times
(pgBufferUsage, pgStatBlockWrite/ReadTime). Whereas, I would need to do
an accum diff for every one of those.
- Melanie
[1]
https://www.postgresql.org/message-id/1feedb83-7aa9-cb4b-5086-598349d3f555%40gmail.com
From 5c02cd9cb784bf22f756fb9d92f4bd29ba2e744a Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplage...@gmail.com>
Date: Mon, 6 Mar 2023 10:41:51 -0500
Subject: [PATCH v5] Track IO times in pg_stat_io
Add IO timing for reads, writes, extends, and fsyncs to pg_stat_io.
Reviewed-by: Bertrand Drouvot <bertranddrouvot...@gmail.com>
Reviewed-by: Andres Freund <and...@anarazel.de>
Discussion: https://www.postgresql.org/message-id/flat/CAAKRu_ay5iKmnbXZ3DsauViF3eMxu4m1oNnJXqV_HyqYeg55Ww%40mail.gmail.com
---
doc/src/sgml/monitoring.sgml | 59 +++++++++++++++
src/backend/catalog/system_views.sql | 4 ++
src/backend/storage/buffer/bufmgr.c | 56 ++++++---------
src/backend/storage/buffer/localbuf.c | 6 +-
src/backend/storage/smgr/md.c | 27 ++++---
src/backend/utils/activity/pgstat.c | 77 +++++++++++++++++++-
src/backend/utils/activity/pgstat_io.c | 99 +++++++++++++++++++++-----
src/backend/utils/adt/pgstatfuncs.c | 48 +++++++++++--
src/include/catalog/pg_proc.dat | 6 +-
src/include/pgstat.h | 14 +++-
src/test/regress/expected/rules.out | 6 +-
11 files changed, 325 insertions(+), 77 deletions(-)
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 6249bb50d0..ad3667f258 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -3814,6 +3814,18 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</entry>
</row>
+ <row>
+ <entry role="catalog_table_entry">
+ <para role="column_definition">
+ <structfield>read_time</structfield> <type>double precision</type>
+ </para>
+ <para>
+ Time spent in read operations in milliseconds (if <xref
+ linkend="guc-track-io-timing"/> is enabled, otherwise zero)
+ </para>
+ </entry>
+ </row>
+
<row>
<entry role="catalog_table_entry">
<para role="column_definition">
@@ -3826,6 +3838,18 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</entry>
</row>
+ <row>
+ <entry role="catalog_table_entry">
+ <para role="column_definition">
+ <structfield>write_time</structfield> <type>double precision</type>
+ </para>
+ <para>
+ Time spent in write operations in milliseconds (if <xref
+ linkend="guc-track-io-timing"/> is enabled, otherwise zero)
+ </para>
+ </entry>
+ </row>
+
<row>
<entry role="catalog_table_entry">
<para role="column_definition">
@@ -3838,6 +3862,18 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</entry>
</row>
+ <row>
+ <entry role="catalog_table_entry">
+ <para role="column_definition">
+ <structfield>extend_time</structfield> <type>double precision</type>
+ </para>
+ <para>
+ Time spent in extend operations in milliseconds (if <xref
+ linkend="guc-track-io-timing"/> is enabled, otherwise zero)
+ </para>
+ </entry>
+ </row>
+
<row>
<entry role="catalog_table_entry">
<para role="column_definition">
@@ -3902,6 +3938,18 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</entry>
</row>
+ <row>
+ <entry role="catalog_table_entry">
+ <para role="column_definition">
+ <structfield>fsync_time</structfield> <type>double precision</type>
+ </para>
+ <para>
+ Time spent in fsync operations in milliseconds (if <xref
+ linkend="guc-track-io-timing"/> is enabled, otherwise zero)
+ </para>
+ </entry>
+ </row>
+
<row>
<entry role="catalog_table_entry">
<para role="column_definition">
@@ -3967,6 +4015,17 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
</itemizedlist>
</para>
+ <note>
+ <para>
+ Columns tracking I/O time will only be non-zero when <xref
+ linkend="guc-track-io-timing"/> is enabled. The user should be careful when
+ using these columns in combination with their corresponding operations to
+ ensure that <varname>track_io_timing</varname> was enabled for the entire
+ time since the last reset.
+ </para>
+ </note>
+
+
</sect2>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 34ca0e739f..39391bc2fc 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1123,12 +1123,16 @@ SELECT
b.io_object,
b.io_context,
b.reads,
+ b.read_time,
b.writes,
+ b.write_time,
b.extends,
+ b.extend_time,
b.op_bytes,
b.evictions,
b.reuses,
b.fsyncs,
+ b.fsync_time,
b.stats_reset
FROM pg_stat_get_io() b;
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 0a05577b68..64857f1ff6 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1000,12 +1000,17 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
if (isExtend)
{
+ instr_time io_start;
+
/* new buffers are zero-filled */
MemSet((char *) bufBlock, 0, BLCKSZ);
+
+ io_start = pgstat_io_start();
+
/* don't set checksum for all-zero page */
smgrextend(smgr, forkNum, blockNum, bufBlock, false);
- pgstat_count_io_op(io_object, io_context, IOOP_EXTEND);
+ pgstat_io_end(io_start, io_object, io_context, IOOP_EXTEND);
/*
* NB: we're *not* doing a ScheduleBufferTagForWriteback here;
@@ -1024,25 +1029,13 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
MemSet((char *) bufBlock, 0, BLCKSZ);
else
{
- instr_time io_start,
- io_time;
+ instr_time io_start;
- if (track_io_timing)
- INSTR_TIME_SET_CURRENT(io_start);
- else
- INSTR_TIME_SET_ZERO(io_start);
+ io_start = pgstat_io_start();
smgrread(smgr, forkNum, blockNum, bufBlock);
- pgstat_count_io_op(io_object, io_context, IOOP_READ);
-
- if (track_io_timing)
- {
- INSTR_TIME_SET_CURRENT(io_time);
- INSTR_TIME_SUBTRACT(io_time, io_start);
- pgstat_count_buffer_read_time(INSTR_TIME_GET_MICROSEC(io_time));
- INSTR_TIME_ADD(pgBufferUsage.blk_read_time, io_time);
- }
+ pgstat_io_end(io_start, io_object, io_context, IOOP_READ);
/* check for garbage data */
if (!PageIsVerifiedExtended((Page) bufBlock, blockNum,
@@ -2848,6 +2841,7 @@ BufferGetTag(Buffer buffer, RelFileLocator *rlocator, ForkNumber *forknum,
*blknum = bufHdr->tag.blockNum;
}
+
/*
* FlushBuffer
* Physically write out a shared buffer.
@@ -2873,8 +2867,7 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
{
XLogRecPtr recptr;
ErrorContextCallback errcallback;
- instr_time io_start,
- io_time;
+ instr_time io_start;
Block bufBlock;
char *bufToWrite;
uint32 buf_state;
@@ -2949,10 +2942,7 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
*/
bufToWrite = PageSetChecksumCopy((Page) bufBlock, buf->tag.blockNum);
- if (track_io_timing)
- INSTR_TIME_SET_CURRENT(io_start);
- else
- INSTR_TIME_SET_ZERO(io_start);
+ io_start = pgstat_io_start();
/*
* bufToWrite is either the shared buffer or a copy, as appropriate.
@@ -2981,17 +2971,7 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOObject io_object,
* When a strategy is not in use, the write can only be a "regular" write
* of a dirty shared buffer (IOCONTEXT_NORMAL IOOP_WRITE).
*/
- pgstat_count_io_op(IOOBJECT_RELATION, io_context, IOOP_WRITE);
-
- if (track_io_timing)
- {
- INSTR_TIME_SET_CURRENT(io_time);
- INSTR_TIME_SUBTRACT(io_time, io_start);
- pgstat_count_buffer_write_time(INSTR_TIME_GET_MICROSEC(io_time));
- INSTR_TIME_ADD(pgBufferUsage.blk_write_time, io_time);
- }
-
- pgBufferUsage.shared_blks_written++;
+ pgstat_io_end(io_start, IOOBJECT_RELATION, io_context, IOOP_WRITE);
/*
* Mark the buffer as clean (unless BM_JUST_DIRTIED has become set) and
@@ -3597,6 +3577,7 @@ FlushRelationBuffers(Relation rel)
for (i = 0; i < NLocBuffer; i++)
{
uint32 buf_state;
+ instr_time io_start;
bufHdr = GetLocalBufferDescriptor(i);
if (BufTagMatchesRelFileLocator(&bufHdr->tag, &rel->rd_locator) &&
@@ -3616,6 +3597,12 @@ FlushRelationBuffers(Relation rel)
PageSetChecksumInplace(localpage, bufHdr->tag.blockNum);
+ /*
+ * TODO: is it okay that this formerly didn't count
+ * pgBufferUsage or pgStatBlockReadTime
+ */
+ io_start = pgstat_io_start();
+
smgrwrite(RelationGetSmgr(rel),
BufTagGetForkNum(&bufHdr->tag),
bufHdr->tag.blockNum,
@@ -3625,13 +3612,14 @@ FlushRelationBuffers(Relation rel)
buf_state &= ~(BM_DIRTY | BM_JUST_DIRTIED);
pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
- pgstat_count_io_op(IOOBJECT_TEMP_RELATION, IOCONTEXT_NORMAL, IOOP_WRITE);
+ pgstat_io_end(io_start, IOOBJECT_TEMP_RELATION, IOCONTEXT_NORMAL, IOOP_WRITE);
/* Pop the error context stack */
error_context_stack = errcallback.previous;
}
}
+
return;
}
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index 5325ddb663..af45a72934 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -220,6 +220,7 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
*/
if (buf_state & BM_DIRTY)
{
+ instr_time io_start;
SMgrRelation oreln;
Page localpage = (char *) LocalBufHdrGetBlock(bufHdr);
@@ -228,6 +229,8 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
PageSetChecksumInplace(localpage, bufHdr->tag.blockNum);
+ io_start = pgstat_io_start();
+
/* And write... */
smgrwrite(oreln,
BufTagGetForkNum(&bufHdr->tag),
@@ -239,8 +242,7 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
buf_state &= ~BM_DIRTY;
pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
- pgstat_count_io_op(IOOBJECT_TEMP_RELATION, IOCONTEXT_NORMAL, IOOP_WRITE);
- pgBufferUsage.local_blks_written++;
+ pgstat_io_end(io_start, IOOBJECT_TEMP_RELATION, IOCONTEXT_NORMAL, IOOP_WRITE);
}
/*
diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 352958e1fe..2440211f03 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -1030,6 +1030,17 @@ register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
if (!RegisterSyncRequest(&tag, SYNC_REQUEST, false /* retryOnError */ ))
{
+ instr_time io_start = pgstat_io_start();
+
+ ereport(DEBUG1,
+ (errmsg_internal("could not forward fsync request because request queue is full")));
+
+ if (FileSync(seg->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC) < 0)
+ ereport(data_sync_elevel(ERROR),
+ (errcode_for_file_access(),
+ errmsg("could not fsync file \"%s\": %m",
+ FilePathName(seg->mdfd_vfd))));
+
/*
* We have no way of knowing if the current IOContext is
* IOCONTEXT_NORMAL or IOCONTEXT_[BULKREAD, BULKWRITE, VACUUM] at this
@@ -1041,16 +1052,7 @@ register_dirty_segment(SMgrRelation reln, ForkNumber forknum, MdfdVec *seg)
* IOCONTEXT_NORMAL is likely clearer when investigating the number of
* backend fsyncs.
*/
- pgstat_count_io_op(IOOBJECT_RELATION, IOCONTEXT_NORMAL, IOOP_FSYNC);
-
- ereport(DEBUG1,
- (errmsg_internal("could not forward fsync request because request queue is full")));
-
- if (FileSync(seg->mdfd_vfd, WAIT_EVENT_DATA_FILE_SYNC) < 0)
- ereport(data_sync_elevel(ERROR),
- (errcode_for_file_access(),
- errmsg("could not fsync file \"%s\": %m",
- FilePathName(seg->mdfd_vfd))));
+ pgstat_io_end(io_start, IOOBJECT_RELATION, IOCONTEXT_NORMAL, IOOP_FSYNC);
}
}
@@ -1399,6 +1401,7 @@ int
mdsyncfiletag(const FileTag *ftag, char *path)
{
SMgrRelation reln = smgropen(ftag->rlocator, InvalidBackendId);
+ instr_time io_start;
File file;
bool need_to_close;
int result,
@@ -1425,6 +1428,8 @@ mdsyncfiletag(const FileTag *ftag, char *path)
need_to_close = true;
}
+ io_start = pgstat_io_start();
+
/* Sync the file. */
result = FileSync(file, WAIT_EVENT_DATA_FILE_SYNC);
save_errno = errno;
@@ -1432,7 +1437,7 @@ mdsyncfiletag(const FileTag *ftag, char *path)
if (need_to_close)
FileClose(file);
- pgstat_count_io_op(IOOBJECT_RELATION, IOCONTEXT_NORMAL, IOOP_FSYNC);
+ pgstat_io_end(io_start, IOOBJECT_RELATION, IOCONTEXT_NORMAL, IOOP_FSYNC);
errno = save_errno;
return result;
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index b125802b21..9f5f041d7c 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -95,9 +95,11 @@
#include "access/transam.h"
#include "access/xact.h"
+#include "executor/instrument.h"
#include "lib/dshash.h"
#include "pgstat.h"
#include "port/atomics.h"
+#include "storage/bufmgr.h"
#include "storage/fd.h"
#include "storage/ipc.h"
#include "storage/lwlock.h"
@@ -108,7 +110,6 @@
#include "utils/pgstat_internal.h"
#include "utils/timestamp.h"
-
/* ----------
* Timer definitions.
*
@@ -906,6 +907,80 @@ pgstat_have_entry(PgStat_Kind kind, Oid dboid, Oid objoid)
return pgstat_get_entry_ref(kind, dboid, objoid, false, NULL) != NULL;
}
+instr_time
+pgstat_io_start(void)
+{
+ instr_time io_start;
+
+ if (track_io_timing)
+ INSTR_TIME_SET_CURRENT(io_start);
+ else
+ INSTR_TIME_SET_ZERO(io_start);
+
+ return io_start;
+}
+
+void
+pgstat_io_end(instr_time io_start, IOObject io_object,
+ IOContext io_context, IOOp io_op)
+{
+ instr_time io_time;
+
+ if (track_io_timing)
+ {
+ INSTR_TIME_SET_CURRENT(io_time);
+ INSTR_TIME_SUBTRACT(io_time, io_start);
+ pgstat_count_io_time(io_object, io_context, io_op, io_time);
+
+ if (io_op == IOOP_WRITE)
+ {
+ if (io_object == IOOBJECT_RELATION)
+ {
+ /* TODO: AFAICT, pgstat_count_buffer_write_time is only called */
+ /* for shared buffers whereas pgstat_count_buffer_read_time is */
+ /* called for temp relations and shared buffers. */
+ /*
+ * is this intentional and should I match current behavior or
+ * not?
+ */
+ pgstat_count_buffer_write_time(INSTR_TIME_GET_MICROSEC(io_time));
+ INSTR_TIME_ADD(pgBufferUsage.blk_write_time, io_time);
+ }
+ }
+ else if (io_op == IOOP_READ)
+ {
+ pgstat_count_buffer_read_time(INSTR_TIME_GET_MICROSEC(io_time));
+ if (io_object == IOOBJECT_RELATION)
+ {
+ INSTR_TIME_ADD(pgBufferUsage.blk_read_time, io_time);
+ }
+ }
+ }
+
+ pgstat_count_io_op(io_object, io_context, io_op);
+
+ if (io_op == IOOP_WRITE)
+ {
+ if (io_object == IOOBJECT_RELATION)
+ pgBufferUsage.shared_blks_written++;
+ else if (io_object == IOOBJECT_TEMP_RELATION)
+ pgBufferUsage.local_blks_written++;
+ }
+
+ /*
+ * TODO: this is normally done later in ReadBuffer_common() is it okay to
+ * do here?
+ */
+ else if (io_op == IOOP_READ)
+ {
+ if (io_object == IOOBJECT_RELATION)
+ pgBufferUsage.shared_blks_read++;
+ else if (io_object == IOOBJECT_TEMP_RELATION)
+ pgBufferUsage.local_blks_read++;
+ }
+}
+
+
/*
* Ensure snapshot for fixed-numbered 'kind' exists.
*
diff --git a/src/backend/utils/activity/pgstat_io.c b/src/backend/utils/activity/pgstat_io.c
index af5d554610..fe09cbf16d 100644
--- a/src/backend/utils/activity/pgstat_io.c
+++ b/src/backend/utils/activity/pgstat_io.c
@@ -25,36 +25,47 @@ bool have_iostats = false;
/*
* Check that stats have not been counted for any combination of IOObject,
- * IOContext, and IOOp which are not tracked for the passed-in BackendType. The
- * passed-in PgStat_BktypeIO must contain stats from the BackendType specified
- * by the second parameter. Caller is responsible for locking the passed-in
- * PgStat_BktypeIO, if needed.
+ * IOContext, and IOOp which are not tracked for the passed-in BackendType. If
+ * the IOOp is not counted for this combination but IO time is otherwise
+ * tracked for this IOOp, check that IO time has not been counted for this
+ * combination. If stats are tracked for this combination and IO times are
+ * non-zero, counts should be non-zero.
+ *
+ * The passed-in PgStat_BktypeIO must contain stats from the BackendType
+ * specified by the second parameter. Caller is responsible for locking the
+ * passed-in PgStat_BktypeIO, if needed.
*/
bool
pgstat_bktype_io_stats_valid(PgStat_BktypeIO *backend_io,
BackendType bktype)
{
- bool bktype_tracked = pgstat_tracks_io_bktype(bktype);
-
for (int io_object = 0; io_object < IOOBJECT_NUM_TYPES; io_object++)
{
for (int io_context = 0; io_context < IOCONTEXT_NUM_TYPES; io_context++)
{
- /*
- * Don't bother trying to skip to the next loop iteration if
- * pgstat_tracks_io_object() would return false here. We still
- * need to validate that each counter is zero anyway.
- */
for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
{
- /* No stats, so nothing to validate */
- if (backend_io->data[io_object][io_context][io_op] == 0)
+ /* we do track it */
+ if (pgstat_tracks_io_op(bktype, io_object, io_context, io_op))
+ {
+ /* ensure that if IO times are non-zero, counts are > 0 */
+ if (backend_io->times[io_object][io_context][io_op] != 0 &&
+ backend_io->counts[io_object][io_context][io_op] <= 0)
+ return false;
+
continue;
+ }
- /* There are stats and there shouldn't be */
- if (!bktype_tracked ||
- !pgstat_tracks_io_op(bktype, io_object, io_context, io_op))
+ /* we don't track it, and it is not 0 */
+ if (backend_io->counts[io_object][io_context][io_op] != 0)
return false;
+
+ /* we don't track this IOOp, so make sure its IO time is zero */
+ if (pgstat_tracks_io_time(io_op) > -1)
+ {
+ if (backend_io->times[io_object][io_context][io_op] != 0)
+ return false;
+ }
}
}
}
@@ -70,7 +81,21 @@ pgstat_count_io_op(IOObject io_object, IOContext io_context, IOOp io_op)
Assert((unsigned int) io_op < IOOP_NUM_TYPES);
Assert(pgstat_tracks_io_op(MyBackendType, io_object, io_context, io_op));
- PendingIOStats.data[io_object][io_context][io_op]++;
+ PendingIOStats.counts[io_object][io_context][io_op]++;
+
+ have_iostats = true;
+}
+
+void
+pgstat_count_io_time(IOObject io_object, IOContext io_context, IOOp io_op, instr_time time)
+{
+ Assert(io_object < IOOBJECT_NUM_TYPES);
+ Assert(io_context < IOCONTEXT_NUM_TYPES);
+ Assert(io_op < IOOP_NUM_TYPES);
+ Assert(pgstat_tracks_io_op(MyBackendType, io_object, io_context, io_op));
+ Assert(pgstat_tracks_io_time(io_op) != -1);
+
+ INSTR_TIME_ADD(PendingIOStats.pending_times[io_object][io_context][io_op], time);
have_iostats = true;
}
@@ -114,8 +139,17 @@ pgstat_flush_io(bool nowait)
for (int io_context = 0; io_context < IOCONTEXT_NUM_TYPES; io_context++)
{
for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
- bktype_shstats->data[io_object][io_context][io_op] +=
- PendingIOStats.data[io_object][io_context][io_op];
+ {
+ instr_time time;
+
+ bktype_shstats->counts[io_object][io_context][io_op] +=
+ PendingIOStats.counts[io_object][io_context][io_op];
+
+ time = PendingIOStats.pending_times[io_object][io_context][io_op];
+
+ bktype_shstats->times[io_object][io_context][io_op] +=
+ INSTR_TIME_GET_MICROSEC(time);
+ }
}
}
@@ -384,3 +418,30 @@ pgstat_tracks_io_op(BackendType bktype, IOObject io_object,
return true;
}
+
+/*
+ * PgStat_BktypeIO->times contains IO times for IOOps. For simplicity this
+ * array has a spot for every IOOp. pgstat_tracks_io_time() is the source of
+ * truth for which IOOps have corresponding IO times.
+ */
+IOOp
+pgstat_tracks_io_time(IOOp io_op)
+{
+ switch (io_op)
+ {
+ case IOOP_READ:
+ return IOOP_READ;
+ case IOOP_WRITE:
+ return IOOP_WRITE;
+ case IOOP_EXTEND:
+ return IOOP_EXTEND;
+ case IOOP_FSYNC:
+ return IOOP_FSYNC;
+ case IOOP_EVICT:
+ case IOOP_REUSE:
+ return -1;
+ }
+
+ elog(ERROR, "unrecognized IOOp value: %d", io_op);
+ pg_unreachable();
+}
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 35c6d46555..60fdda1a14 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1255,12 +1255,16 @@ typedef enum io_stat_col
IO_COL_IO_OBJECT,
IO_COL_IO_CONTEXT,
IO_COL_READS,
+ IO_COL_READ_TIME,
IO_COL_WRITES,
+ IO_COL_WRITE_TIME,
IO_COL_EXTENDS,
+ IO_COL_EXTEND_TIME,
IO_COL_CONVERSION,
IO_COL_EVICTIONS,
IO_COL_REUSES,
IO_COL_FSYNCS,
+ IO_COL_FSYNC_TIME,
IO_COL_RESET_TIME,
IO_NUM_COLUMNS,
} io_stat_col;
@@ -1292,6 +1296,28 @@ pgstat_get_io_op_index(IOOp io_op)
pg_unreachable();
}
+/*
+ * Get the number of the column containing IO times for the specified IOOp. If
+ * the specified IOOp is one for which IO time is not tracked, return -1. Note
+ * that this function assumes that IO time for an IOOp is displayed in the view
+ * in the column directly after the IOOp counts.
+ */
+static io_stat_col
+pgstat_get_io_time_index(IOOp io_op)
+{
+ if (pgstat_tracks_io_time(io_op) == -1)
+ return -1;
+
+ return pgstat_get_io_op_index(io_op) + 1;
+}
+
+static inline
+PgStat_Counter
+pg_stat_micro_to_millisecs(PgStat_Counter val_microsec)
+{
+ return val_microsec * 0.001;
+}
+
Datum
pg_stat_get_io(PG_FUNCTION_ARGS)
{
@@ -1359,20 +1385,32 @@ pg_stat_get_io(PG_FUNCTION_ARGS)
for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
{
- int col_idx = pgstat_get_io_op_index(io_op);
+ PgStat_Counter count = bktype_stats->counts[io_obj][io_context][io_op];
+ int i = pgstat_get_io_op_index(io_op);
/*
* Some combinations of BackendType and IOOp, of IOContext
* and IOOp, and of IOObject and IOOp are not tracked. Set
* these cells in the view NULL.
*/
- nulls[col_idx] = !pgstat_tracks_io_op(bktype, io_obj, io_context, io_op);
+ if (pgstat_tracks_io_op(bktype, io_obj, io_context, io_op))
+ values[i] = Int64GetDatum(count);
+ else
+ nulls[i] = true;
+ }
- if (nulls[col_idx])
+ for (int io_op = 0; io_op < IOOP_NUM_TYPES; io_op++)
+ {
+ PgStat_Counter time = bktype_stats->times[io_obj][io_context][io_op];
+ int i = pgstat_get_io_time_index(io_op);
+
+ if (i == -1)
continue;
- values[col_idx] =
- Int64GetDatum(bktype_stats->data[io_obj][io_context][io_op]);
+ if (!nulls[pgstat_get_io_op_index(io_op)])
+ values[i] = Float8GetDatum(pg_stat_micro_to_millisecs(time));
+ else
+ nulls[i] = true;
}
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index fbc4aade49..a16c49fad2 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5728,9 +5728,9 @@
proname => 'pg_stat_get_io', provolatile => 'v',
prorows => '30', proretset => 't',
proparallel => 'r', prorettype => 'record', proargtypes => '',
- proallargtypes => '{text,text,text,int8,int8,int8,int8,int8,int8,int8,timestamptz}',
- proargmodes => '{o,o,o,o,o,o,o,o,o,o,o}',
- proargnames => '{backend_type,io_object,io_context,reads,writes,extends,op_bytes,evictions,reuses,fsyncs,stats_reset}',
+ proallargtypes => '{text,text,text,int8,float8,int8,float8,int8,float8,int8,int8,int8,int8,float8,timestamptz}',
+ proargmodes => '{o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}',
+ proargnames => '{backend_type,io_object,io_context,reads,read_time,writes,write_time,extends,extend_time,op_bytes,evictions,reuses,fsyncs,fsync_time,stats_reset}',
prosrc => 'pg_stat_get_io' },
{ oid => '1136', descr => 'statistics: information about WAL activity',
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 1e418b682b..288a8c7c0e 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -304,7 +304,12 @@ typedef enum IOOp
typedef struct PgStat_BktypeIO
{
- PgStat_Counter data[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
+ PgStat_Counter counts[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
+ union
+ {
+ instr_time pending_times[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
+ PgStat_Counter times[IOOBJECT_NUM_TYPES][IOCONTEXT_NUM_TYPES][IOOP_NUM_TYPES];
+ };
} PgStat_BktypeIO;
typedef struct PgStat_IO
@@ -466,6 +471,11 @@ extern TimestampTz pgstat_get_stat_snapshot_timestamp(bool *have_snapshot);
extern PgStat_Kind pgstat_get_kind_from_str(char *kind_str);
extern bool pgstat_have_entry(PgStat_Kind kind, Oid dboid, Oid objoid);
+extern instr_time pgstat_io_start(void);
+
+extern void pgstat_io_end(instr_time io_start, IOObject io_object,
+ IOContext io_context, IOOp io_op);
+
/*
* Functions in pgstat_archiver.c
@@ -498,6 +508,7 @@ extern PgStat_CheckpointerStats *pgstat_fetch_stat_checkpointer(void);
extern bool pgstat_bktype_io_stats_valid(PgStat_BktypeIO *context_ops,
BackendType bktype);
extern void pgstat_count_io_op(IOObject io_object, IOContext io_context, IOOp io_op);
+extern void pgstat_count_io_time(IOObject io_object, IOContext io_context, IOOp io_op, instr_time time);
extern PgStat_IO *pgstat_fetch_stat_io(void);
extern const char *pgstat_get_io_context_name(IOContext io_context);
extern const char *pgstat_get_io_object_name(IOObject io_object);
@@ -507,6 +518,7 @@ extern bool pgstat_tracks_io_object(BackendType bktype,
IOObject io_object, IOContext io_context);
extern bool pgstat_tracks_io_op(BackendType bktype, IOObject io_object,
IOContext io_context, IOOp io_op);
+extern IOOp pgstat_tracks_io_time(IOOp io_op);
/*
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index e953d1f515..5434851314 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1880,14 +1880,18 @@ pg_stat_io| SELECT backend_type,
io_object,
io_context,
reads,
+ read_time,
writes,
+ write_time,
extends,
+ extend_time,
op_bytes,
evictions,
reuses,
fsyncs,
+ fsync_time,
stats_reset
- FROM pg_stat_get_io() b(backend_type, io_object, io_context, reads, writes, extends, op_bytes, evictions, reuses, fsyncs, stats_reset);
+ FROM pg_stat_get_io() b(backend_type, io_object, io_context, reads, read_time, writes, write_time, extends, extend_time, op_bytes, evictions, reuses, fsyncs, fsync_time, stats_reset);
pg_stat_progress_analyze| SELECT s.pid,
s.datid,
d.datname,
--
2.37.2
