Thanks for the review!
On Tue, Jul 12, 2022 at 4:06 AM Kyotaro Horiguchi <horikyota....@gmail.com>
wrote:
> At Mon, 11 Jul 2022 22:22:28 -0400, Melanie Plageman <
> melanieplage...@gmail.com> wrote in
> > Hi,
> >
> > In the attached patch set, I've added in missing IO operations for
> > certain IO Paths as well as enumerating in the commit message which IO
> > Paths and IO Operations are not currently counted and or not possible.
> >
> > There is a TODO in HandleWalWriterInterrupts() about removing
> > pgstat_report_wal() since it is immediately before a proc_exit()
>
> Right. walwriter does that without needing the explicit call.
>
I have deleted it.
>
> > I was wondering if LocalBufferAlloc() should increment the counter or if
> > I should wait until GetLocalBufferStorage() to increment the counter.
>
> Depends on what "allocate" means. Different from shared buffers, local
> buffers are taken from OS then allocated to page. OS-allcoated pages
> are restricted by num_temp_buffers so I think what we're interested in
> is the count incremented by LocalBuferAlloc(). (And it is the parallel
> of alloc for shared-buffers)
>
I've left it in LocalBufferAlloc().
>
> > I also realized that I am not differentiating between IOPATH_SHARED and
> > IOPATH_STRATEGY for IOOP_FSYNC. But, given that we don't know what type
> > of buffer we are fsync'ing by the time we call register_dirty_segment(),
> > I'm not sure how we would fix this.
>
> I think there scarcely happens flush for strategy-loaded buffers. If
> that is sensible, IOOP_FSYNC would not make much sense for
> IOPATH_STRATEGY.
>
Why would it be less likely for a backend to do its own fsync when
flushing a dirty strategy buffer than a regular dirty shared buffer?
>
> > > IMO it'd be a good idea to add pgstat_report_io_ops() to
> > > pgstat_report_vacuum()/analyze(), so that the stats for a longrunning
> > > autovac worker get updated more regularly.
> > >
> >
> > noted and fixed.
>
> > > How about moving the pgstat_report_io_ops() into
> > > pgstat_report_bgwriter(), pgstat_report_autovacuum() etc? Seems
> > > unnecessary to have multiple pgstat_* calls in these places.
> > >
> > >
> > >
> > noted and fixed.
>
> + * Also report IO Operations statistics
>
> I think that the function comment also should mention this.
>
I've added comments at the top of all these functions.
>
> > > Wonder if it's worth making the lock specific to the backend type?
> > >
> >
> > I've added another Lock into PgStat_IOPathOps so that each BackendType
> > can be locked separately. But, I've also kept the lock in
> > PgStatShared_BackendIOPathOps so that reset_all and snapshot could be
> > done easily.
>
> Looks fine about the lock separation.
>
Actually, I think it is not safe to use both of these locks. So for
picking one method, it is probably better to go with the locks in
PgStat_IOPathOps, it will be more efficient for flush (and not for
fetching and resetting), so that is probably the way to go, right?
> By the way, in the following line:
>
> +
> &pgStatLocal.shmem->io_ops.stats[backend_type_get_idx(MyBackendType)];
>
> backend_type_get_idx(x) is actually (x - 1) plus assertion on the
> value range. And the only use-case is here. There's an reverse
> function and also used only at one place.
>
> + Datum backend_type_desc =
> +
> CStringGetTextDatum(GetBackendTypeDesc(idx_get_backend_type(i)));
>
> In this usage GetBackendTypeDesc() gracefully treats out-of-domain
> values but idx_get_backend_type keenly kills the process for the
> same. This is inconsistent.
>
> My humbel opinion on this is we don't define the two functions and
> replace the calls to them with (x +/- 1). Addition to that, I think
> we should not abort() by invalid backend types. In that sense, I
> wonder if we could use B_INVALIDth element for this purpose.
>
I think that GetBackendTypeDesc() should probably also error out for an
unknown value.
I would be open to not using the helper functions. I thought it would be
less error-prone, but since it is limited to the code in
pgstat_io_ops.c, it is probably okay. Let me think a bit more.
Could you explain more about what you mean about using B_INVALID
BackendType?
>
> > > > + LWLockAcquire(&stats_shmem->lock, LW_SHARED);
> > > > + memcpy(&reset, reset_offset, sizeof(stats_shmem->stats));
> > > > + LWLockRelease(&stats_shmem->lock);
> > >
> > > Which then also means that you don't need the reset offset stuff. It's
> > > only there because with the changecount approach we can't take a lock
> to
> > > reset the stats (since there is no lock). With a lock you can just
> reset
> > > the shared state.
> > >
> >
> > Yes, I believe I have cleaned up all of this embarrassing mess. I use the
> > lock in PgStatShared_BackendIOPathOps for reset all and snapshot and the
> > locks in PgStat_IOPathOps for flush.
>
> Looks fine, but I think pgstat_flush_io_ops() need more comments like
> other pgstat_flush_* functions.
>
> + for (int i = 0; i < BACKEND_NUM_TYPES; i++)
> + stats_shmem->stats[i].stat_reset_timestamp = ts;
>
> I'm not sure we need a separate reset timestamp for each backend type
> but SLRU counter does the same thing..
>
Yes, I think for SLRU stats it is because you can reset individual SLRU
stats. Also there is no wrapper data structure to put it in. I could
keep it in PgStatShared_BackendIOPathOps since you have to reset all IO
operation stats at once, but I am thinking of getting rid of
PgStatShared_BackendIOPathOps since it is not needed if I only keep the
locks in PgStat_IOPathOps and make the global shared value an array of
PgStat_IOPathOps.
>
> > > > +pgstat_report_io_ops(void)
> > > > +{
> > >
> > > This shouldn't be needed - the flush function above can be used.
> > >
> >
> > Fixed.
>
> The commit message of 0002 contains that name:p
>
Thanks! Fixed.
>
> > > > +const char *
> > > > +pgstat_io_path_desc(IOPath io_path)
> > > > +{
> > > > + const char *io_path_desc = "Unknown IO Path";
> > > > +
> > >
> > > This should be unreachable, right?
> > >
> >
> > Changed it to an error.
>
> + elog(ERROR, "Attempt to describe an unknown IOPath");
>
> I think we usually spell it as ("unrecognized IOPath value: %d", io_path).
>
I have changed to this.
>
> > > > From f2b5b75f5063702cbc3c64efdc1e7ef3cf1acdb4 Mon Sep 17 00:00:00
> 2001
> > > > From: Melanie Plageman <melanieplage...@gmail.com>
> > > > Date: Mon, 4 Jul 2022 15:44:17 -0400
> > > > Subject: [PATCH v22 3/3] Add system view tracking IO ops per backend
> type
> > >
> > > > Add pg_stat_buffers, a system view which tracks the number of IO
> > > > operations (allocs, writes, fsyncs, and extends) done through each IO
> > > > path (e.g. shared buffers, local buffers, unbuffered IO) by each
> type of
> > > > backend.
> > >
> > > I think I like pg_stat_io a bit better? Nearly everything in here seems
> > > to fit better in that.
> > >
> > > I guess we could split out buffers allocated, but that's actually
> > > interesting in the context of the kind of IO too.
> > >
> >
> > changed it to pg_stat_io
>
> A bit different thing, but I felt a little uneasy about some uses of
> "pgstat_io_ops". IOOp looks like a neighbouring word of IOPath. On the
> other hand, actually iopath is used as an attribute of io_ops in many
> places. Couldn't we be more consistent about the relationship between
> the names?
>
> IOOp -> PgStat_IOOpType
> IOPath -> PgStat_IOPath
> PgStat_IOOpCOonters -> PgStat_IOCounters
> PgStat_IOPathOps -> PgStat_IO
> pgstat_count_io_op -> pgstat_count_io
> ...
>
> (Better wordings are welcome.)
>
Let me think about naming and make changes in the next version.
> > > Would be nice to have something testing that the ringbuffer stats stuff
> > > does something sensible - that feels not entirely trivial.
> > >
> > >
> > I've added a test to test that reused strategy buffers are counted as
> > allocs. I would like to add a test which checks that if a buffer in the
> > ring is pinned and thus not reused, that it is not counted as a strategy
> > alloc, but I found it challenging without a way to pause vacuuming, pin
> > a buffer, then resume vacuuming.
>
> ===
>
> If I'm not missing something, in BufferAlloc, when strategy is not
> used and the victim is dirty, iopath is determined based on the
> uninitialized from_ring. It seems to me from_ring is equivalent to
> strategy_current_was_in_ring. And if StrategyGetBuffer has set
> from_ring to false, StratetgyRejectBuffer may set it to true, which is
> is wrong. The logic around there seems to need a rethink.
>
> What can we read from the values separated to Shared and Strategy?
>
I have changed this local variable to only be used for communicating if
the buffer which was not rejected by StrategyRejectBuffer() was from the
ring or not for the purposes of counting strategy writes. I could add an
accessor for this member (strategy->current_was_in_ring) if that makes
more sense? For strategy allocs, I just use
strategy->current_was_in_ring inside of StrategyGetBuffer() since this
has access to that member of the struct.
Currently, strategy allocs count only reuses of a strategy buffer (not
initial shared buffers which are added to the ring).
strategy writes count only the writing out of dirty buffers which are
already in the ring and are being reused.
Alternatively, we could also count as strategy allocs all those buffers
which are added to the ring and count as strategy writes all those
shared buffers which are dirty when initially added to the ring.
- Melanie
From fdf6486b6a1546bb393aae7aa9e97604abc31d86 Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplage...@gmail.com>
Date: Tue, 28 Jun 2022 11:33:04 -0400
Subject: [PATCH v24 1/3] Add BackendType for standalone backends
All backends should have a BackendType to enable statistics reporting
per BackendType.
Add a new BackendType for standalone backends, B_STANDALONE_BACKEND (and
alphabetize the BackendTypes). Both the bootstrap backend and single
user mode backends will have BackendType B_STANDALONE_BACKEND.
Author: Melanie Plageman <melanieplage...@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAAKRu_aaq33UnG4TXq3S-OSXGWj1QGf0sU%2BECH4tNwGFNERkZA%40mail.gmail.com
---
src/backend/utils/init/miscinit.c | 17 +++++++++++------
src/include/miscadmin.h | 5 +++--
2 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index eb43b2c5e5..07e6db1a1c 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -176,6 +176,8 @@ InitStandaloneProcess(const char *argv0)
{
Assert(!IsPostmasterEnvironment);
+ MyBackendType = B_STANDALONE_BACKEND;
+
/*
* Start our win32 signal implementation
*/
@@ -255,6 +257,9 @@ GetBackendTypeDesc(BackendType backendType)
case B_INVALID:
backendDesc = "not initialized";
break;
+ case B_ARCHIVER:
+ backendDesc = "archiver";
+ break;
case B_AUTOVAC_LAUNCHER:
backendDesc = "autovacuum launcher";
break;
@@ -273,6 +278,12 @@ GetBackendTypeDesc(BackendType backendType)
case B_CHECKPOINTER:
backendDesc = "checkpointer";
break;
+ case B_LOGGER:
+ backendDesc = "logger";
+ break;
+ case B_STANDALONE_BACKEND:
+ backendDesc = "standalone backend";
+ break;
case B_STARTUP:
backendDesc = "startup";
break;
@@ -285,12 +296,6 @@ GetBackendTypeDesc(BackendType backendType)
case B_WAL_WRITER:
backendDesc = "walwriter";
break;
- case B_ARCHIVER:
- backendDesc = "archiver";
- break;
- case B_LOGGER:
- backendDesc = "logger";
- break;
}
return backendDesc;
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index ea9a56d395..5276bf25a1 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -316,18 +316,19 @@ extern void SwitchBackToLocalLatch(void);
typedef enum BackendType
{
B_INVALID = 0,
+ B_ARCHIVER,
B_AUTOVAC_LAUNCHER,
B_AUTOVAC_WORKER,
B_BACKEND,
B_BG_WORKER,
B_BG_WRITER,
B_CHECKPOINTER,
+ B_LOGGER,
+ B_STANDALONE_BACKEND,
B_STARTUP,
B_WAL_RECEIVER,
B_WAL_SENDER,
B_WAL_WRITER,
- B_ARCHIVER,
- B_LOGGER,
} BackendType;
extern PGDLLIMPORT BackendType MyBackendType;
--
2.34.1
From 546b9a06e33e1bf6ab7c8de2d5db93e77f77c39c Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplage...@gmail.com>
Date: Mon, 4 Jul 2022 15:44:17 -0400
Subject: [PATCH v24 3/3] Add system view tracking IO ops per backend type
Add pg_stat_io, a system view which tracks the number of IOOp (allocs,
writes, fsyncs, and extends) done through each IOPath (e.g. shared
buffers, local buffers, unbuffered IO) by each type of backend.
Some of these should always be zero. For example, checkpointer does not
use a BufferAccessStrategy (currently), so the "strategy" IOPath for
checkpointer will be 0 for all IOOps. All possible combinations of
IOPath and IOOp are enumerated in the view but not all are populated or
even possible at this point.
View stats are fetched from statistics incremented when a backend
performs an IO Operation and maintained by the cumulative statistics
subsystem.
Each row of the view is stats for a particular BackendType for a
particular IOPath (e.g. shared buffer accesses by checkpointer) and
each column in the view is the total number of IO Operations done (e.g.
writes).
So a cell in the view would be, for example, the number of shared
buffers written by checkpointer since the last stats reset.
Note that some of the cells in the view are redundant with fields in
pg_stat_bgwriter (e.g. buffers_backend), however these have been kept in
pg_stat_bgwriter for backwards compatibility. Deriving the redundant
pg_stat_bgwriter stats from the IO operations stats structures was also
problematic due to the separate reset targets for 'bgwriter' and
'io'.
Suggested by Andres Freund
Author: Melanie Plageman <melanieplage...@gmail.com>
Reviewed-by: Justin Pryzby <pry...@telsasoft.com>, Kyotaro Horiguchi <horikyota....@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/20200124195226.lth52iydq2n2uilq%40alap3.anarazel.de
---
doc/src/sgml/monitoring.sgml | 108 ++++++++++++++++++++++++++-
src/backend/catalog/system_views.sql | 11 +++
src/backend/utils/adt/pgstatfuncs.c | 66 ++++++++++++++++
src/include/catalog/pg_proc.dat | 9 +++
src/test/regress/expected/rules.out | 8 ++
src/test/regress/expected/stats.out | 59 +++++++++++++++
src/test/regress/sql/stats.sql | 34 +++++++++
7 files changed, 294 insertions(+), 1 deletion(-)
diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 4549c2560e..775ecf2f21 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -448,6 +448,15 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
</entry>
</row>
+ <row>
+ <entry><structname>pg_stat_io</structname><indexterm><primary>pg_stat_io</primary></indexterm></entry>
+ <entry>A row for each IO path for each backend type showing
+ statistics about backend IO operations. See
+ <link linkend="monitoring-pg-stat-io-view">
+ <structname>pg_stat_io</structname></link> for details.
+ </entry>
+ </row>
+
<row>
<entry><structname>pg_stat_wal</structname><indexterm><primary>pg_stat_wal</primary></indexterm></entry>
<entry>One row only, showing statistics about WAL activity. See
@@ -3595,7 +3604,102 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
<structfield>stats_reset</structfield> <type>timestamp with time zone</type>
</para>
<para>
- Time at which these statistics were last reset
+ Time at which these statistics were last reset.
+ </para></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ </sect2>
+
+ <sect2 id="monitoring-pg-stat-io-view">
+ <title><structname>pg_stat_io</structname></title>
+
+ <indexterm>
+ <primary>pg_stat_io</primary>
+ </indexterm>
+
+ <para>
+ The <structname>pg_stat_io</structname> view has a row for each backend
+ type for each possible IO path containing global data for the cluster for
+ that backend and IO path.
+ </para>
+
+ <table id="pg-stat-io-view" xreflabel="pg_stat_io">
+ <title><structname>pg_stat_io</structname> View</title>
+ <tgroup cols="1">
+ <thead>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ Column Type
+ </para>
+ <para>
+ Description
+ </para></entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>backend_type</structfield> <type>text</type>
+ </para>
+ <para>
+ Type of backend (e.g. background worker, autovacuum worker).
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>io_path</structfield> <type>text</type>
+ </para>
+ <para>
+ IO path taken (e.g. shared buffers, direct).
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>alloc</structfield> <type>bigint</type>
+ </para>
+ <para>
+ Number of buffers allocated.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>extend</structfield> <type>bigint</type>
+ </para>
+ <para>
+ Number of blocks extended.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>fsync</structfield> <type>bigint</type>
+ </para>
+ <para>
+ Number of blocks fsynced.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>write</structfield> <type>bigint</type>
+ </para>
+ <para>
+ Number of blocks written.
+ </para></entry>
+ </row>
+
+ <row>
+ <entry role="catalog_table_entry"><para role="column_definition">
+ <structfield>stats_reset</structfield> <type>timestamp with time zone</type>
+ </para>
+ <para>
+ Time at which these statistics were last reset.
</para></entry>
</row>
</tbody>
@@ -5355,6 +5459,8 @@ SELECT pid, wait_event_type, wait_event FROM pg_stat_activity WHERE wait_event i
the <structname>pg_stat_bgwriter</structname>
view, <literal>archiver</literal> to reset all the counters shown in
the <structname>pg_stat_archiver</structname> view,
+ <literal>io</literal> to reset all the counters shown in the
+ <structname>pg_stat_io</structname> view,
<literal>wal</literal> to reset all the counters shown in the
<structname>pg_stat_wal</structname> view or
<literal>recovery_prefetch</literal> to reset all the counters shown
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index fedaed533b..b0b2d39e28 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -1115,6 +1115,17 @@ CREATE VIEW pg_stat_bgwriter AS
pg_stat_get_buf_alloc() AS buffers_alloc,
pg_stat_get_bgwriter_stat_reset_time() AS stats_reset;
+CREATE VIEW pg_stat_io AS
+SELECT
+ b.backend_type,
+ b.io_path,
+ b.alloc,
+ b.extend,
+ b.fsync,
+ b.write,
+ b.stats_reset
+FROM pg_stat_get_io() b;
+
CREATE VIEW pg_stat_wal AS
SELECT
w.wal_records,
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 6259cc4f4c..30aff64860 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1739,6 +1739,72 @@ pg_stat_get_buf_alloc(PG_FUNCTION_ARGS)
PG_RETURN_INT64(pgstat_fetch_stat_bgwriter()->buf_alloc);
}
+/*
+* When adding a new column to the pg_stat_io view, add a new enum
+* value here above IO_NUM_COLUMNS.
+*/
+enum
+{
+ IO_COLUMN_BACKEND_TYPE,
+ IO_COLUMN_IO_PATH,
+ IO_COLUMN_ALLOCS,
+ IO_COLUMN_EXTENDS,
+ IO_COLUMN_FSYNCS,
+ IO_COLUMN_WRITES,
+ IO_COLUMN_RESET_TIME,
+ IO_NUM_COLUMNS,
+};
+
+Datum
+pg_stat_get_io(PG_FUNCTION_ARGS)
+{
+ PgStat_IOPathOps *io_path_ops;
+ ReturnSetInfo *rsinfo;
+ Datum reset_time;
+
+ SetSingleFuncCall(fcinfo, 0);
+ io_path_ops = pgstat_fetch_backend_io_path_ops();
+ rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
+
+ /*
+ * Currently it is not permitted to reset IO operation stats for individual
+ * IO Paths or individual BackendTypes. All IO Operation statistics are
+ * reset together. As such, it is easiest to reuse the first reset timestamp
+ * available.
+ */
+ reset_time = TimestampTzGetDatum(io_path_ops->stat_reset_timestamp);
+
+ for (int i = 0; i < BACKEND_NUM_TYPES; i++)
+ {
+ PgStat_IOOpCounters *counters = io_path_ops->data;
+ Datum backend_type_desc =
+ CStringGetTextDatum(GetBackendTypeDesc(idx_get_backend_type(i)));
+ /* const char *log_name = GetBackendTypeDesc(idx_get_backend_type(i)); */
+
+ for (int j = 0; j < IOPATH_NUM_TYPES; j++)
+ {
+ Datum values[IO_NUM_COLUMNS];
+ bool nulls[IO_NUM_COLUMNS];
+ memset(values, 0, sizeof(values));
+ memset(nulls, 0, sizeof(nulls));
+
+ values[IO_COLUMN_BACKEND_TYPE] = backend_type_desc;
+ values[IO_COLUMN_IO_PATH] = CStringGetTextDatum(pgstat_io_path_desc(j));
+ values[IO_COLUMN_RESET_TIME] = TimestampTzGetDatum(reset_time);
+ values[IO_COLUMN_ALLOCS] = Int64GetDatum(counters->allocs);
+ values[IO_COLUMN_EXTENDS] = Int64GetDatum(counters->extends);
+ values[IO_COLUMN_FSYNCS] = Int64GetDatum(counters->fsyncs);
+ values[IO_COLUMN_WRITES] = Int64GetDatum(counters->writes);
+
+ tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc, values, nulls);
+ counters++;
+ }
+ io_path_ops++;
+ }
+
+ return (Datum) 0;
+}
+
/*
* Returns statistics of WAL activity
*/
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 2e41f4d9e8..e9662fdc04 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -5646,6 +5646,15 @@
proname => 'pg_stat_get_buf_alloc', provolatile => 's', proparallel => 'r',
prorettype => 'int8', proargtypes => '', prosrc => 'pg_stat_get_buf_alloc' },
+{ oid => '8459', descr => 'statistics: counts of all IO operations done through all IO paths by each type of backend.',
+ proname => 'pg_stat_get_io', provolatile => 's', proisstrict => 'f',
+ prorows => '52', proretset => 't',
+ proparallel => 'r', prorettype => 'record', proargtypes => '',
+ proallargtypes => '{text,text,int8,int8,int8,int8,timestamptz}',
+ proargmodes => '{o,o,o,o,o,o,o}',
+ proargnames => '{backend_type,io_path,alloc,extend,fsync,write,stats_reset}',
+ prosrc => 'pg_stat_get_io' },
+
{ oid => '1136', descr => 'statistics: information about WAL activity',
proname => 'pg_stat_get_wal', proisstrict => 'f', provolatile => 's',
proparallel => 'r', prorettype => 'record', proargtypes => '',
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index 7ec3d2688f..3b05af9ac8 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1873,6 +1873,14 @@ pg_stat_gssapi| SELECT s.pid,
s.gss_enc AS encrypted
FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, ssl_client_dn, ssl_client_serial, ssl_issuer_dn, gss_auth, gss_princ, gss_enc, leader_pid, query_id)
WHERE (s.client_port IS NOT NULL);
+pg_stat_io| SELECT b.backend_type,
+ b.io_path,
+ b.alloc,
+ b.extend,
+ b.fsync,
+ b.write,
+ b.stats_reset
+ FROM pg_stat_get_io() b(backend_type, io_path, alloc, extend, fsync, write, stats_reset);
pg_stat_progress_analyze| SELECT s.pid,
s.datid,
d.datname,
diff --git a/src/test/regress/expected/stats.out b/src/test/regress/expected/stats.out
index 5b0ebf090f..6dade03b65 100644
--- a/src/test/regress/expected/stats.out
+++ b/src/test/regress/expected/stats.out
@@ -554,4 +554,63 @@ SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_test3, trunc_stats_test4;
DROP TABLE prevstats;
+-- Test that writes to Shared Buffers are tracked in pg_stat_io
+SELECT sum(write) AS io_sum_shared_writes_before FROM pg_stat_io WHERE io_path = 'Shared' \gset
+CREATE TABLE test_io_shared_writes(a int);
+INSERT INTO test_io_shared_writes SELECT i FROM generate_series(1,100)i;
+CHECKPOINT;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush
+--------------------------
+
+(1 row)
+
+SELECT sum(write) AS io_sum_shared_writes_after FROM pg_stat_io WHERE io_path = 'Shared' \gset
+SELECT :io_sum_shared_writes_after > :io_sum_shared_writes_before;
+ ?column?
+----------
+ t
+(1 row)
+
+DROP TABLE test_io_shared_writes;
+-- Test that extends of temporary tables are tracked in pg_stat_io
+CREATE TEMPORARY TABLE test_io_local_extends(a int);
+SELECT sum(extend) AS io_sum_local_extends_before FROM pg_stat_io WHERE io_path = 'Local' \gset
+INSERT INTO test_io_local_extends VALUES(1);
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush
+--------------------------
+
+(1 row)
+
+SELECT sum(extend) AS io_sum_local_extends_after FROM pg_stat_io WHERE io_path = 'Local' \gset
+SELECT :io_sum_local_extends_after > :io_sum_local_extends_before;
+ ?column?
+----------
+ t
+(1 row)
+
+-- Test that, when using a Strategy, reusing buffers from the Strategy ring
+-- count as "Strategy" allocs.
+CREATE TABLE test_io_strategy_stats(a INT, b INT);
+ALTER TABLE test_io_strategy_stats SET (autovacuum_enabled = 'false');
+INSERT INTO test_io_strategy_stats SELECT i, i from generate_series(1,8000)i;
+-- Ensure that the next VACUUM will need to perform IO
+VACUUM (FULL) test_io_strategy_stats;
+SELECT sum(alloc) AS io_sum_strategy_allocs_before FROM pg_stat_io WHERE io_path = 'Strategy' \gset
+VACUUM (PARALLEL 0) test_io_strategy_stats;
+SELECT pg_stat_force_next_flush();
+ pg_stat_force_next_flush
+--------------------------
+
+(1 row)
+
+SELECT sum(alloc) AS io_sum_strategy_allocs_after FROM pg_stat_io WHERE io_path = 'Strategy' \gset
+SELECT :io_sum_strategy_allocs_after > :io_sum_strategy_allocs_before;
+ ?column?
+----------
+ t
+(1 row)
+
+DROP TABLE test_io_strategy_stats;
-- End of Stats Test
diff --git a/src/test/regress/sql/stats.sql b/src/test/regress/sql/stats.sql
index 3f3cf8fb56..fbd3977605 100644
--- a/src/test/regress/sql/stats.sql
+++ b/src/test/regress/sql/stats.sql
@@ -285,4 +285,38 @@ SELECT pg_stat_get_live_tuples(:drop_stats_test_subxact_oid);
DROP TABLE trunc_stats_test, trunc_stats_test1, trunc_stats_test2, trunc_stats_test3, trunc_stats_test4;
DROP TABLE prevstats;
+
+-- Test that writes to Shared Buffers are tracked in pg_stat_io
+SELECT sum(write) AS io_sum_shared_writes_before FROM pg_stat_io WHERE io_path = 'Shared' \gset
+CREATE TABLE test_io_shared_writes(a int);
+INSERT INTO test_io_shared_writes SELECT i FROM generate_series(1,100)i;
+CHECKPOINT;
+SELECT pg_stat_force_next_flush();
+SELECT sum(write) AS io_sum_shared_writes_after FROM pg_stat_io WHERE io_path = 'Shared' \gset
+SELECT :io_sum_shared_writes_after > :io_sum_shared_writes_before;
+DROP TABLE test_io_shared_writes;
+
+-- Test that extends of temporary tables are tracked in pg_stat_io
+CREATE TEMPORARY TABLE test_io_local_extends(a int);
+SELECT sum(extend) AS io_sum_local_extends_before FROM pg_stat_io WHERE io_path = 'Local' \gset
+INSERT INTO test_io_local_extends VALUES(1);
+SELECT pg_stat_force_next_flush();
+SELECT sum(extend) AS io_sum_local_extends_after FROM pg_stat_io WHERE io_path = 'Local' \gset
+SELECT :io_sum_local_extends_after > :io_sum_local_extends_before;
+
+-- Test that, when using a Strategy, reusing buffers from the Strategy ring
+-- count as "Strategy" allocs.
+CREATE TABLE test_io_strategy_stats(a INT, b INT);
+ALTER TABLE test_io_strategy_stats SET (autovacuum_enabled = 'false');
+INSERT INTO test_io_strategy_stats SELECT i, i from generate_series(1,8000)i;
+-- Ensure that the next VACUUM will need to perform IO
+VACUUM (FULL) test_io_strategy_stats;
+SELECT sum(alloc) AS io_sum_strategy_allocs_before FROM pg_stat_io WHERE io_path = 'Strategy' \gset
+VACUUM (PARALLEL 0) test_io_strategy_stats;
+SELECT pg_stat_force_next_flush();
+SELECT sum(alloc) AS io_sum_strategy_allocs_after FROM pg_stat_io WHERE io_path = 'Strategy' \gset
+SELECT :io_sum_strategy_allocs_after > :io_sum_strategy_allocs_before;
+DROP TABLE test_io_strategy_stats;
+
+
-- End of Stats Test
--
2.34.1
From 16016c4d1989ca154b4894912281d290e093639e Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplage...@gmail.com>
Date: Wed, 29 Jun 2022 18:37:42 -0400
Subject: [PATCH v24 2/3] Track IO operation statistics
Introduce "IOOp", an IO operation done by a backend, and "IOPath", the
location or type of IO done by a backend. For example, the checkpointer
may write a shared buffer out. This would be counted as an IOOp write on
an IOPath IOPATH_SHARED by BackendType "checkpointer".
Each IOOp (alloc, fsync, extend, write) is counted per IOPath
(direct, local, shared, or strategy) through a call to
pgstat_count_io_op().
The primary concern of these statistics is IO operations on data blocks
during the course of normal database operations. IO done by, for
example, the archiver or syslogger is not counted in these statistics.
IOPATH_LOCAL and IOPATH_SHARED IOPaths concern operations on local
and shared buffers.
The IOPATH_STRATEGY IOPath concerns buffers alloc'd/written/read/fsync'd
as part of a BufferAccessStrategy.
The IOPATH_DIRECT IOPath concerns blocks of IO which are read, written,
or fsync'd using smgrwrite/extend/immedsync directly (as opposed to
through [Local]BufferAlloc()).
Note that this commit does not add code to increment IOPATH_DIRECT. A
future patch adding wrappers for smgrwrite(), smgrextend(), and
smgrimmedsync() would provide a good location to call
pgstat_count_io_op() for unbuffered IO and avoid regressions for future
users of these functions.
IOOP_ALLOC is counted for IOPATH_SHARED and IOPATH_LOCAL whenever a
buffer is acquired through [Local]BufferAlloc(). IOOP_ALLOC is invalid
for IOPATH_DIRECT. IOOP_ALLOC for IOPATH_STRATEGY is counted whenever a
buffer already in the strategy ring is reused.
Stats on IOOps for all IOPaths for a backend are initially accumulated
locally.
Later they are flushed to shared memory and accumulated with those from
all other backends, exited and live.
Some BackendTypes will not execute pgstat_report_stat() and thus must
explicitly call pgstat_flush_io_ops() in order to flush their backend
local IO operation statistics to shared memory.
Author: Melanie Plageman <melanieplage...@gmail.com>
Reviewed-by: Justin Pryzby <pry...@telsasoft.com>, Kyotaro Horiguchi <horikyota....@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/20200124195226.lth52iydq2n2uilq%40alap3.anarazel.de
---
src/backend/bootstrap/bootstrap.c | 1 +
src/backend/postmaster/checkpointer.c | 1 +
src/backend/postmaster/walwriter.c | 11 --
src/backend/storage/buffer/bufmgr.c | 51 +++++-
src/backend/storage/buffer/freelist.c | 48 ++++-
src/backend/storage/buffer/localbuf.c | 5 +
src/backend/storage/sync/sync.c | 2 +
src/backend/utils/activity/Makefile | 1 +
src/backend/utils/activity/pgstat.c | 24 +++
src/backend/utils/activity/pgstat_bgwriter.c | 7 +-
.../utils/activity/pgstat_checkpointer.c | 7 +-
src/backend/utils/activity/pgstat_database.c | 8 +-
src/backend/utils/activity/pgstat_io_ops.c | 168 ++++++++++++++++++
src/backend/utils/activity/pgstat_relation.c | 14 +-
src/backend/utils/activity/pgstat_wal.c | 4 +-
src/backend/utils/adt/pgstatfuncs.c | 4 +-
src/include/miscadmin.h | 2 +
src/include/pgstat.h | 53 ++++++
src/include/storage/buf_internals.h | 2 +-
src/include/utils/backend_status.h | 34 ++++
src/include/utils/pgstat_internal.h | 17 ++
21 files changed, 432 insertions(+), 32 deletions(-)
create mode 100644 src/backend/utils/activity/pgstat_io_ops.c
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 088556ab54..963b05321e 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -33,6 +33,7 @@
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#include "pg_getopt.h"
+#include "pgstat.h"
#include "storage/bufmgr.h"
#include "storage/bufpage.h"
#include "storage/condition_variable.h"
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index 5fc076fc14..a06331e1eb 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -1116,6 +1116,7 @@ ForwardSyncRequest(const FileTag *ftag, SyncRequestType type)
if (!AmBackgroundWriterProcess())
CheckpointerShmem->num_backend_fsync++;
LWLockRelease(CheckpointerCommLock);
+ pgstat_count_io_op(IOOP_FSYNC, IOPATH_SHARED);
return false;
}
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index e926f8c27c..beb46dcb55 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -293,18 +293,7 @@ HandleWalWriterInterrupts(void)
}
if (ShutdownRequestPending)
- {
- /*
- * Force reporting remaining WAL statistics at process exit.
- *
- * Since pgstat_report_wal is invoked with 'force' is false in main
- * loop to avoid overloading the cumulative stats system, there may
- * exist unreported stats counters for the WAL writer.
- */
- pgstat_report_wal(true);
-
proc_exit(0);
- }
/* Perform logging of memory contexts of this process */
if (LogMemoryContextPending)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index c7d7abcd73..846297f273 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -482,7 +482,7 @@ static BufferDesc *BufferAlloc(SMgrRelation smgr,
BlockNumber blockNum,
BufferAccessStrategy strategy,
bool *foundPtr);
-static void FlushBuffer(BufferDesc *buf, SMgrRelation reln);
+static void FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOPath iopath);
static void FindAndDropRelationBuffers(RelFileLocator rlocator,
ForkNumber forkNum,
BlockNumber nForkBlock,
@@ -980,6 +980,16 @@ ReadBuffer_common(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
if (isExtend)
{
+ IOPath io_path;
+
+ if (isLocalBuf)
+ io_path = IOPATH_LOCAL;
+ else if (strategy != NULL)
+ io_path = IOPATH_STRATEGY;
+ else
+ io_path = IOPATH_SHARED;
+
+ pgstat_count_io_op(IOOP_EXTEND, io_path);
/* new buffers are zero-filled */
MemSet((char *) bufBlock, 0, BLCKSZ);
/* don't set checksum for all-zero page */
@@ -1180,6 +1190,7 @@ BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
/* Loop here in case we have to try another victim buffer */
for (;;)
{
+ bool write_from_ring = false;
/*
* Ensure, while the spinlock's not yet held, that there's a free
* refcount entry.
@@ -1227,6 +1238,7 @@ BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
if (LWLockConditionalAcquire(BufferDescriptorGetContentLock(buf),
LW_SHARED))
{
+ IOPath iopath;
/*
* If using a nondefault strategy, and writing the buffer
* would require a WAL flush, let the strategy decide whether
@@ -1244,7 +1256,7 @@ BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
UnlockBufHdr(buf, buf_state);
if (XLogNeedsFlush(lsn) &&
- StrategyRejectBuffer(strategy, buf))
+ StrategyRejectBuffer(strategy, buf, &write_from_ring))
{
/* Drop lock/pin and loop around for another buffer */
LWLockRelease(BufferDescriptorGetContentLock(buf));
@@ -1253,13 +1265,27 @@ BufferAlloc(SMgrRelation smgr, char relpersistence, ForkNumber forkNum,
}
}
+ /*
+ * When a strategy is in use, if the target dirty buffer is an existing
+ * strategy buffer being reused, count this as a strategy write for the
+ * purposes of IO Operations statistics tracking.
+ *
+ * All dirty shared buffers upon first being added to the ring will be
+ * counted as shared buffer writes.
+ *
+ * When a strategy is not in use, the write can only be a only be a
+ * "regular" write of a dirty shared buffer.
+ */
+
+ iopath = write_from_ring ? IOPATH_STRATEGY : IOPATH_SHARED;
+
/* OK, do the I/O */
TRACE_POSTGRESQL_BUFFER_WRITE_DIRTY_START(forkNum, blockNum,
smgr->smgr_rlocator.locator.spcOid,
smgr->smgr_rlocator.locator.dbOid,
smgr->smgr_rlocator.locator.relNumber);
- FlushBuffer(buf, NULL);
+ FlushBuffer(buf, NULL, iopath);
LWLockRelease(BufferDescriptorGetContentLock(buf));
ScheduleBufferTagForWriteback(&BackendWritebackContext,
@@ -2563,7 +2589,7 @@ SyncOneBuffer(int buf_id, bool skip_recently_used, WritebackContext *wb_context)
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
- FlushBuffer(bufHdr, NULL);
+ FlushBuffer(bufHdr, NULL, IOPATH_SHARED);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
@@ -2810,9 +2836,12 @@ BufferGetTag(Buffer buffer, RelFileLocator *rlocator, ForkNumber *forknum,
*
* If the caller has an smgr reference for the buffer's relation, pass it
* as the second parameter. If not, pass NULL.
+ *
+ * IOPath will always be IOPATH_SHARED except when a buffer access strategy is
+ * used and the buffer being flushed is a buffer from the strategy ring.
*/
static void
-FlushBuffer(BufferDesc *buf, SMgrRelation reln)
+FlushBuffer(BufferDesc *buf, SMgrRelation reln, IOPath iopath)
{
XLogRecPtr recptr;
ErrorContextCallback errcallback;
@@ -2892,6 +2921,8 @@ FlushBuffer(BufferDesc *buf, SMgrRelation reln)
*/
bufToWrite = PageSetChecksumCopy((Page) bufBlock, buf->tag.blockNum);
+ pgstat_count_io_op(IOOP_WRITE, iopath);
+
if (track_io_timing)
INSTR_TIME_SET_CURRENT(io_start);
@@ -3539,6 +3570,8 @@ FlushRelationBuffers(Relation rel)
localpage,
false);
+ pgstat_count_io_op(IOOP_WRITE, IOPATH_LOCAL);
+
buf_state &= ~(BM_DIRTY | BM_JUST_DIRTIED);
pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
@@ -3574,7 +3607,7 @@ FlushRelationBuffers(Relation rel)
{
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
- FlushBuffer(bufHdr, RelationGetSmgr(rel));
+ FlushBuffer(bufHdr, RelationGetSmgr(rel), IOPATH_SHARED);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
UnpinBuffer(bufHdr, true);
}
@@ -3669,7 +3702,7 @@ FlushRelationsAllBuffers(SMgrRelation *smgrs, int nrels)
{
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
- FlushBuffer(bufHdr, srelent->srel);
+ FlushBuffer(bufHdr, srelent->srel, IOPATH_SHARED);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
UnpinBuffer(bufHdr, true);
}
@@ -3877,7 +3910,7 @@ FlushDatabaseBuffers(Oid dbid)
{
PinBuffer_Locked(bufHdr);
LWLockAcquire(BufferDescriptorGetContentLock(bufHdr), LW_SHARED);
- FlushBuffer(bufHdr, NULL);
+ FlushBuffer(bufHdr, NULL, IOPATH_SHARED);
LWLockRelease(BufferDescriptorGetContentLock(bufHdr));
UnpinBuffer(bufHdr, true);
}
@@ -3904,7 +3937,7 @@ FlushOneBuffer(Buffer buffer)
Assert(LWLockHeldByMe(BufferDescriptorGetContentLock(bufHdr)));
- FlushBuffer(bufHdr, NULL);
+ FlushBuffer(bufHdr, NULL, IOPATH_SHARED);
}
/*
diff --git a/src/backend/storage/buffer/freelist.c b/src/backend/storage/buffer/freelist.c
index 990e081aae..8ab88341ce 100644
--- a/src/backend/storage/buffer/freelist.c
+++ b/src/backend/storage/buffer/freelist.c
@@ -15,6 +15,7 @@
*/
#include "postgres.h"
+#include "pgstat.h"
#include "port/atomics.h"
#include "storage/buf_internals.h"
#include "storage/bufmgr.h"
@@ -212,8 +213,18 @@ StrategyGetBuffer(BufferAccessStrategy strategy, uint32 *buf_state)
if (strategy != NULL)
{
buf = GetBufferFromRing(strategy, buf_state);
- if (buf != NULL)
+ if (strategy->current_was_in_ring)
+ {
+ /*
+ * When a strategy is in use, reused buffers from the strategy ring
+ * will be counted as allocations for the purposes of IO Operation
+ * statistics tracking. However, even when a strategy is in use, if
+ * a new buffer must be allocated from shared buffers and added to
+ * the ring, this is counted as a IOPATH_SHARED allocation.
+ */
+ pgstat_count_io_op(IOOP_ALLOC, IOPATH_STRATEGY);
return buf;
+ }
}
/*
@@ -247,6 +258,7 @@ StrategyGetBuffer(BufferAccessStrategy strategy, uint32 *buf_state)
* the rate of buffer consumption. Note that buffers recycled by a
* strategy object are intentionally not counted here.
*/
+ pgstat_count_io_op(IOOP_ALLOC, IOPATH_SHARED);
pg_atomic_fetch_add_u32(&StrategyControl->numBufferAllocs, 1);
/*
@@ -682,16 +694,37 @@ AddBufferToRing(BufferAccessStrategy strategy, BufferDesc *buf)
* if this buffer should be written and re-used.
*/
bool
-StrategyRejectBuffer(BufferAccessStrategy strategy, BufferDesc *buf)
+StrategyRejectBuffer(BufferAccessStrategy strategy, BufferDesc *buf, bool *write_from_ring)
{
- /* We only do this in bulkread mode */
+
+ /*
+ * We only reject reusing and writing out the strategy buffer this in
+ * bulkread mode.
+ */
if (strategy->btype != BAS_BULKREAD)
+ {
+ /*
+ * If the buffer was from the ring and we are not rejecting it, consider it
+ * a write of a strategy buffer.
+ */
+ if (strategy->current_was_in_ring)
+ *write_from_ring = true;
return false;
+ }
- /* Don't muck with behavior of normal buffer-replacement strategy */
+ /*
+ * Don't muck with behavior of normal buffer-replacement strategy.
+ * Though we are not rejecting this buffer, write_from_ring will remain false
+ * because shared buffers that are added to the ring, either initially or as
+ * part of an expansion, are not considered strategy writes for the purposes
+ * of IO Operation statistics.
+ */
if (!strategy->current_was_in_ring ||
strategy->buffers[strategy->current] != BufferDescriptorGetBuffer(buf))
+ {
+ *write_from_ring = false;
return false;
+ }
/*
* Remove the dirty buffer from the ring; necessary to prevent infinite
@@ -699,5 +732,12 @@ StrategyRejectBuffer(BufferAccessStrategy strategy, BufferDesc *buf)
*/
strategy->buffers[strategy->current] = InvalidBuffer;
+ /*
+ * Though caller should not use this flag since the buffer is being rejected
+ * (and it should have been initialized to false anyway), set it here for
+ * clarity.
+ */
+ *write_from_ring = false;
+
return true;
}
diff --git a/src/backend/storage/buffer/localbuf.c b/src/backend/storage/buffer/localbuf.c
index 9c038851d7..58738d6684 100644
--- a/src/backend/storage/buffer/localbuf.c
+++ b/src/backend/storage/buffer/localbuf.c
@@ -15,6 +15,7 @@
*/
#include "postgres.h"
+#include "pgstat.h"
#include "access/parallel.h"
#include "catalog/catalog.h"
#include "executor/instrument.h"
@@ -123,6 +124,8 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
if (LocalBufHash == NULL)
InitLocalBuffers();
+ pgstat_count_io_op(IOOP_ALLOC, IOPATH_LOCAL);
+
/* See if the desired buffer already exists */
hresult = (LocalBufferLookupEnt *)
hash_search(LocalBufHash, (void *) &newTag, HASH_FIND, NULL);
@@ -226,6 +229,8 @@ LocalBufferAlloc(SMgrRelation smgr, ForkNumber forkNum, BlockNumber blockNum,
localpage,
false);
+ pgstat_count_io_op(IOOP_WRITE, IOPATH_LOCAL);
+
/* Mark not-dirty now in case we error out below */
buf_state &= ~BM_DIRTY;
pg_atomic_unlocked_write_u32(&bufHdr->state, buf_state);
diff --git a/src/backend/storage/sync/sync.c b/src/backend/storage/sync/sync.c
index e1fb631003..20e259edef 100644
--- a/src/backend/storage/sync/sync.c
+++ b/src/backend/storage/sync/sync.c
@@ -432,6 +432,8 @@ ProcessSyncRequests(void)
total_elapsed += elapsed;
processed++;
+ pgstat_count_io_op(IOOP_FSYNC, IOPATH_SHARED);
+
if (log_checkpoints)
elog(DEBUG1, "checkpoint sync: number=%d file=%s time=%.3f ms",
processed,
diff --git a/src/backend/utils/activity/Makefile b/src/backend/utils/activity/Makefile
index a2e8507fd6..0098785089 100644
--- a/src/backend/utils/activity/Makefile
+++ b/src/backend/utils/activity/Makefile
@@ -22,6 +22,7 @@ OBJS = \
pgstat_checkpointer.o \
pgstat_database.o \
pgstat_function.o \
+ pgstat_io_ops.o \
pgstat_relation.o \
pgstat_replslot.o \
pgstat_shmem.o \
diff --git a/src/backend/utils/activity/pgstat.c b/src/backend/utils/activity/pgstat.c
index 88e5dd1b2b..52924e64dd 100644
--- a/src/backend/utils/activity/pgstat.c
+++ b/src/backend/utils/activity/pgstat.c
@@ -359,6 +359,15 @@ static const PgStat_KindInfo pgstat_kind_infos[PGSTAT_NUM_KINDS] = {
.snapshot_cb = pgstat_checkpointer_snapshot_cb,
},
+ [PGSTAT_KIND_IOOPS] = {
+ .name = "io_ops",
+
+ .fixed_amount = true,
+
+ .reset_all_cb = pgstat_io_ops_reset_all_cb,
+ .snapshot_cb = pgstat_io_ops_snapshot_cb,
+ },
+
[PGSTAT_KIND_SLRU] = {
.name = "slru",
@@ -628,6 +637,9 @@ pgstat_report_stat(bool force)
/* flush database / relation / function / ... stats */
partial_flush |= pgstat_flush_pending_entries(nowait);
+ /* flush IO Operations stats */
+ partial_flush |= pgstat_flush_io_ops(nowait);
+
/* flush wal stats */
partial_flush |= pgstat_flush_wal(nowait);
@@ -1312,6 +1324,12 @@ pgstat_write_statsfile(void)
pgstat_build_snapshot_fixed(PGSTAT_KIND_CHECKPOINTER);
write_chunk_s(fpout, &pgStatLocal.snapshot.checkpointer);
+ /*
+ * Write IO Operations stats struct
+ */
+ pgstat_build_snapshot_fixed(PGSTAT_KIND_IOOPS);
+ write_chunk_s(fpout, &pgStatLocal.snapshot.io_path_ops);
+
/*
* Write SLRU stats struct
*/
@@ -1486,6 +1504,12 @@ pgstat_read_statsfile(void)
if (!read_chunk_s(fpin, &shmem->checkpointer.stats))
goto error;
+ /*
+ * Read IO Operations stats struct
+ */
+ if (!read_chunk_s(fpin, &shmem->io_ops.stats))
+ goto error;
+
/*
* Read SLRU stats struct
*/
diff --git a/src/backend/utils/activity/pgstat_bgwriter.c b/src/backend/utils/activity/pgstat_bgwriter.c
index fbb1edc527..3d7f90a1b7 100644
--- a/src/backend/utils/activity/pgstat_bgwriter.c
+++ b/src/backend/utils/activity/pgstat_bgwriter.c
@@ -24,7 +24,7 @@ PgStat_BgWriterStats PendingBgWriterStats = {0};
/*
- * Report bgwriter statistics
+ * Report bgwriter and IO Operation statistics
*/
void
pgstat_report_bgwriter(void)
@@ -56,6 +56,11 @@ pgstat_report_bgwriter(void)
* Clear out the statistics buffer, so it can be re-used.
*/
MemSet(&PendingBgWriterStats, 0, sizeof(PendingBgWriterStats));
+
+ /*
+ * Report IO Operations statistics
+ */
+ pgstat_flush_io_ops(false);
}
/*
diff --git a/src/backend/utils/activity/pgstat_checkpointer.c b/src/backend/utils/activity/pgstat_checkpointer.c
index af8d513e7b..cfcf127210 100644
--- a/src/backend/utils/activity/pgstat_checkpointer.c
+++ b/src/backend/utils/activity/pgstat_checkpointer.c
@@ -24,7 +24,7 @@ PgStat_CheckpointerStats PendingCheckpointerStats = {0};
/*
- * Report checkpointer statistics
+ * Report checkpointer and IO Operation statistics
*/
void
pgstat_report_checkpointer(void)
@@ -62,6 +62,11 @@ pgstat_report_checkpointer(void)
* Clear out the statistics buffer, so it can be re-used.
*/
MemSet(&PendingCheckpointerStats, 0, sizeof(PendingCheckpointerStats));
+
+ /*
+ * Report IO Operation statistics
+ */
+ pgstat_flush_io_ops(false);
}
/*
diff --git a/src/backend/utils/activity/pgstat_database.c b/src/backend/utils/activity/pgstat_database.c
index d9275611f0..d3963f59d0 100644
--- a/src/backend/utils/activity/pgstat_database.c
+++ b/src/backend/utils/activity/pgstat_database.c
@@ -47,7 +47,8 @@ pgstat_drop_database(Oid databaseid)
}
/*
- * Called from autovacuum.c to report startup of an autovacuum process.
+ * Called from autovacuum.c to report startup of an autovacuum process and
+ * flush IO Operation statistics.
* We are called before InitPostgres is done, so can't rely on MyDatabaseId;
* the db OID must be passed in, instead.
*/
@@ -72,6 +73,11 @@ pgstat_report_autovac(Oid dboid)
dbentry->stats.last_autovac_time = GetCurrentTimestamp();
pgstat_unlock_entry(entry_ref);
+
+ /*
+ * Report IO Operation statistics
+ */
+ pgstat_flush_io_ops(false);
}
/*
diff --git a/src/backend/utils/activity/pgstat_io_ops.c b/src/backend/utils/activity/pgstat_io_ops.c
new file mode 100644
index 0000000000..f037d2c7c5
--- /dev/null
+++ b/src/backend/utils/activity/pgstat_io_ops.c
@@ -0,0 +1,168 @@
+/* -------------------------------------------------------------------------
+ *
+ * pgstat_io_ops.c
+ * Implementation of IO operation statistics.
+ *
+ * This file contains the implementation of IO operation statistics. It is kept
+ * separate from pgstat.c to enforce the line between the statistics access /
+ * storage implementation and the details about individual types of
+ * statistics.
+ *
+ * Copyright (c) 2001-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ * src/backend/utils/activity/pgstat_io_ops.c
+ * -------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "utils/pgstat_internal.h"
+
+static PgStat_IOPathOps pending_IOOpStats;
+bool have_ioopstats = false;
+
+
+/*
+ * Flush out locally pending IO Operation statistics entries
+ *
+ * If nowait is true, this function returns false on lock failure. Otherwise
+ * this function always returns true.
+ *
+ * If nowait is true, this function returns true if the lock could not be
+ * acquired. Otherwise return false.
+ */
+bool
+pgstat_flush_io_ops(bool nowait)
+{
+ PgStat_IOPathOps *stats_shmem;
+
+ if (!have_ioopstats)
+ return false;
+
+ stats_shmem =
+ &pgStatLocal.shmem->io_ops.stats[backend_type_get_idx(MyBackendType)];
+
+ if (!nowait)
+ LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
+ else if (!LWLockConditionalAcquire(&stats_shmem->lock, LW_EXCLUSIVE))
+ return true;
+
+
+ for (int i = 0; i < IOPATH_NUM_TYPES; i++)
+ {
+ PgStat_IOOpCounters *sharedent = &stats_shmem->data[i];
+ PgStat_IOOpCounters *pendingent = &pending_IOOpStats.data[i];
+
+#define IO_OP_ACC(fld) sharedent->fld += pendingent->fld
+ IO_OP_ACC(allocs);
+ IO_OP_ACC(extends);
+ IO_OP_ACC(fsyncs);
+ IO_OP_ACC(writes);
+#undef IO_OP_ACC
+ }
+
+ LWLockRelease(&stats_shmem->lock);
+
+ memset(&pending_IOOpStats, 0, sizeof(pending_IOOpStats));
+
+ have_ioopstats = false;
+
+ return false;
+}
+
+void
+pgstat_io_ops_snapshot_cb(void)
+{
+ PgStatShared_BackendIOPathOps *stats_shmem = &pgStatLocal.shmem->io_ops;
+
+ LWLockAcquire(&stats_shmem->lock, LW_SHARED);
+
+ memcpy(pgStatLocal.snapshot.io_path_ops, &stats_shmem->stats,
+ sizeof(stats_shmem->stats));
+
+ LWLockRelease(&stats_shmem->lock);
+}
+
+void
+pgstat_io_ops_reset_all_cb(TimestampTz ts)
+{
+ PgStatShared_BackendIOPathOps *stats_shmem = &pgStatLocal.shmem->io_ops;
+
+ LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
+
+ memset(&stats_shmem->stats, 0, sizeof(stats_shmem->stats));
+
+ for (int i = 0; i < BACKEND_NUM_TYPES; i++)
+ stats_shmem->stats[i].stat_reset_timestamp = ts;
+
+ LWLockRelease(&stats_shmem->lock);
+}
+
+void
+pgstat_count_io_op(IOOp io_op, IOPath io_path)
+{
+ PgStat_IOOpCounters *pending_counters = &pending_IOOpStats.data[io_path];
+
+ switch (io_op)
+ {
+ case IOOP_ALLOC:
+ pending_counters->allocs++;
+ break;
+ case IOOP_EXTEND:
+ pending_counters->extends++;
+ break;
+ case IOOP_FSYNC:
+ pending_counters->fsyncs++;
+ break;
+ case IOOP_WRITE:
+ pending_counters->writes++;
+ break;
+ }
+
+ have_ioopstats = true;
+}
+
+PgStat_IOPathOps *
+pgstat_fetch_backend_io_path_ops(void)
+{
+ pgstat_snapshot_fixed(PGSTAT_KIND_IOOPS);
+
+ return pgStatLocal.snapshot.io_path_ops;
+}
+
+const char *
+pgstat_io_path_desc(IOPath io_path)
+{
+ switch (io_path)
+ {
+ case IOPATH_DIRECT:
+ return "Direct";
+ case IOPATH_LOCAL:
+ return "Local";
+ case IOPATH_SHARED:
+ return "Shared";
+ case IOPATH_STRATEGY:
+ return "Strategy";
+ }
+
+ elog(ERROR, "unrecognized IOPath value: %d", io_path);
+}
+
+const char *
+pgstat_io_op_desc(IOOp io_op)
+{
+ switch (io_op)
+ {
+ case IOOP_ALLOC:
+ return "Alloc";
+ case IOOP_EXTEND:
+ return "Extend";
+ case IOOP_FSYNC:
+ return "Fsync";
+ case IOOP_WRITE:
+ return "Write";
+ }
+
+ elog(ERROR, "unrecognized IOOp value: %d", io_op);
+}
diff --git a/src/backend/utils/activity/pgstat_relation.c b/src/backend/utils/activity/pgstat_relation.c
index a846d9ffb6..0f8048eaa9 100644
--- a/src/backend/utils/activity/pgstat_relation.c
+++ b/src/backend/utils/activity/pgstat_relation.c
@@ -205,7 +205,7 @@ pgstat_drop_relation(Relation rel)
}
/*
- * Report that the table was just vacuumed.
+ * Report that the table was just vacuumed and flush IO Operation statistics.
*/
void
pgstat_report_vacuum(Oid tableoid, bool shared,
@@ -257,10 +257,15 @@ pgstat_report_vacuum(Oid tableoid, bool shared,
}
pgstat_unlock_entry(entry_ref);
+
+ /*
+ * Report IO Operations statistics
+ */
+ pgstat_flush_io_ops(false);
}
/*
- * Report that the table was just analyzed.
+ * Report that the table was just analyzed and flush IO Operation statistics.
*
* Caller must provide new live- and dead-tuples estimates, as well as a
* flag indicating whether to reset the changes_since_analyze counter.
@@ -340,6 +345,11 @@ pgstat_report_analyze(Relation rel,
}
pgstat_unlock_entry(entry_ref);
+
+ /*
+ * Report IO Operations statistics
+ */
+ pgstat_flush_io_ops(false);
}
/*
diff --git a/src/backend/utils/activity/pgstat_wal.c b/src/backend/utils/activity/pgstat_wal.c
index 5a878bd115..9cac407b42 100644
--- a/src/backend/utils/activity/pgstat_wal.c
+++ b/src/backend/utils/activity/pgstat_wal.c
@@ -34,7 +34,7 @@ static WalUsage prevWalUsage;
/*
* Calculate how much WAL usage counters have increased and update
- * shared statistics.
+ * shared WAL and IO Operation statistics.
*
* Must be called by processes that generate WAL, that do not call
* pgstat_report_stat(), like walwriter.
@@ -43,6 +43,8 @@ void
pgstat_report_wal(bool force)
{
pgstat_flush_wal(force);
+
+ pgstat_flush_io_ops(force);
}
/*
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 893690dad5..6259cc4f4c 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -2104,6 +2104,8 @@ pg_stat_reset_shared(PG_FUNCTION_ARGS)
pgstat_reset_of_kind(PGSTAT_KIND_BGWRITER);
pgstat_reset_of_kind(PGSTAT_KIND_CHECKPOINTER);
}
+ else if (strcmp(target, "io") == 0)
+ pgstat_reset_of_kind(PGSTAT_KIND_IOOPS);
else if (strcmp(target, "recovery_prefetch") == 0)
XLogPrefetchResetStats();
else if (strcmp(target, "wal") == 0)
@@ -2112,7 +2114,7 @@ pg_stat_reset_shared(PG_FUNCTION_ARGS)
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("unrecognized reset target: \"%s\"", target),
- errhint("Target must be \"archiver\", \"bgwriter\", \"recovery_prefetch\", or \"wal\".")));
+ errhint("Target must be \"archiver\", \"io\", \"bgwriter\", \"recovery_prefetch\", or \"wal\".")));
PG_RETURN_VOID();
}
diff --git a/src/include/miscadmin.h b/src/include/miscadmin.h
index 5276bf25a1..61e95135f2 100644
--- a/src/include/miscadmin.h
+++ b/src/include/miscadmin.h
@@ -331,6 +331,8 @@ typedef enum BackendType
B_WAL_WRITER,
} BackendType;
+#define BACKEND_NUM_TYPES B_WAL_WRITER
+
extern PGDLLIMPORT BackendType MyBackendType;
extern const char *GetBackendTypeDesc(BackendType backendType);
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index ac28f813b4..36a4b89a58 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -14,6 +14,7 @@
#include "datatype/timestamp.h"
#include "portability/instr_time.h"
#include "postmaster/pgarch.h" /* for MAX_XFN_CHARS */
+#include "storage/lwlock.h"
#include "utils/backend_progress.h" /* for backward compatibility */
#include "utils/backend_status.h" /* for backward compatibility */
#include "utils/relcache.h"
@@ -48,6 +49,7 @@ typedef enum PgStat_Kind
PGSTAT_KIND_ARCHIVER,
PGSTAT_KIND_BGWRITER,
PGSTAT_KIND_CHECKPOINTER,
+ PGSTAT_KIND_IOOPS,
PGSTAT_KIND_SLRU,
PGSTAT_KIND_WAL,
} PgStat_Kind;
@@ -276,6 +278,45 @@ typedef struct PgStat_CheckpointerStats
PgStat_Counter buf_fsync_backend;
} PgStat_CheckpointerStats;
+/*
+ * Types related to counting IO Operations for various IO Paths
+ */
+
+typedef enum IOOp
+{
+ IOOP_ALLOC,
+ IOOP_EXTEND,
+ IOOP_FSYNC,
+ IOOP_WRITE,
+} IOOp;
+
+#define IOOP_NUM_TYPES (IOOP_WRITE + 1)
+
+typedef enum IOPath
+{
+ IOPATH_DIRECT,
+ IOPATH_LOCAL,
+ IOPATH_SHARED,
+ IOPATH_STRATEGY,
+} IOPath;
+
+#define IOPATH_NUM_TYPES (IOPATH_STRATEGY + 1)
+
+typedef struct PgStat_IOOpCounters
+{
+ PgStat_Counter allocs;
+ PgStat_Counter extends;
+ PgStat_Counter fsyncs;
+ PgStat_Counter writes;
+} PgStat_IOOpCounters;
+
+typedef struct PgStat_IOPathOps
+{
+ LWLock lock;
+ PgStat_IOOpCounters data[IOPATH_NUM_TYPES];
+ TimestampTz stat_reset_timestamp;
+} PgStat_IOPathOps;
+
typedef struct PgStat_StatDBEntry
{
PgStat_Counter n_xact_commit;
@@ -453,6 +494,18 @@ extern void pgstat_report_checkpointer(void);
extern PgStat_CheckpointerStats *pgstat_fetch_stat_checkpointer(void);
+/*
+ * Functions in pgstat_io_ops.c
+ */
+
+extern void pgstat_count_io_op(IOOp io_op, IOPath io_path);
+extern bool pgstat_flush_io_ops(bool nowait);
+extern PgStat_IOPathOps *pgstat_fetch_backend_io_path_ops(void);
+extern PgStat_Counter pgstat_fetch_cumulative_io_ops(IOPath io_path, IOOp io_op);
+extern const char *pgstat_io_op_desc(IOOp io_op);
+extern const char *pgstat_io_path_desc(IOPath io_path);
+
+
/*
* Functions in pgstat_database.c
*/
diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h
index 69e45900ba..b69c5f7e3c 100644
--- a/src/include/storage/buf_internals.h
+++ b/src/include/storage/buf_internals.h
@@ -313,7 +313,7 @@ extern BufferDesc *StrategyGetBuffer(BufferAccessStrategy strategy,
uint32 *buf_state);
extern void StrategyFreeBuffer(BufferDesc *buf);
extern bool StrategyRejectBuffer(BufferAccessStrategy strategy,
- BufferDesc *buf);
+ BufferDesc *buf, bool *write_from_ring);
extern int StrategySyncStart(uint32 *complete_passes, uint32 *num_buf_alloc);
extern void StrategyNotifyBgWriter(int bgwprocno);
diff --git a/src/include/utils/backend_status.h b/src/include/utils/backend_status.h
index 7403bca25e..49d062b1af 100644
--- a/src/include/utils/backend_status.h
+++ b/src/include/utils/backend_status.h
@@ -306,6 +306,40 @@ extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
int buflen);
extern uint64 pgstat_get_my_query_id(void);
+/* Utility functions */
+
+/*
+ * When maintaining an array of information about all valid BackendTypes, in
+ * order to avoid wasting the 0th spot, use this helper to convert a valid
+ * BackendType to a valid location in the array (given that no spot is
+ * maintained for B_INVALID BackendType).
+ */
+static inline int backend_type_get_idx(BackendType backend_type)
+{
+ /*
+ * backend_type must be one of the valid backend types. If caller is
+ * maintaining backend information in an array that includes B_INVALID,
+ * this function is unnecessary.
+ */
+ Assert(backend_type > B_INVALID && backend_type <= BACKEND_NUM_TYPES);
+ return backend_type - 1;
+}
+
+/*
+ * When using a value from an array of information about all valid
+ * BackendTypes, add 1 to the index before using it as a BackendType to adjust
+ * for not maintaining a spot for B_INVALID BackendType.
+ */
+static inline BackendType idx_get_backend_type(int idx)
+{
+ int backend_type = idx + 1;
+ /*
+ * If the array includes a spot for B_INVALID BackendType this function is
+ * not required.
+ */
+ Assert(backend_type > B_INVALID && backend_type <= BACKEND_NUM_TYPES);
+ return backend_type;
+}
/* ----------
* Support functions for the SQL-callable functions to
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 9303d05427..adffdd147d 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -329,6 +329,12 @@ typedef struct PgStatShared_Checkpointer
PgStat_CheckpointerStats reset_offset;
} PgStatShared_Checkpointer;
+typedef struct PgStatShared_BackendIOPathOps
+{
+ LWLock lock;
+ PgStat_IOPathOps stats[BACKEND_NUM_TYPES];
+} PgStatShared_BackendIOPathOps;
+
typedef struct PgStatShared_SLRU
{
/* lock protects ->stats */
@@ -419,6 +425,7 @@ typedef struct PgStat_ShmemControl
PgStatShared_Archiver archiver;
PgStatShared_BgWriter bgwriter;
PgStatShared_Checkpointer checkpointer;
+ PgStatShared_BackendIOPathOps io_ops;
PgStatShared_SLRU slru;
PgStatShared_Wal wal;
} PgStat_ShmemControl;
@@ -442,6 +449,8 @@ typedef struct PgStat_Snapshot
PgStat_CheckpointerStats checkpointer;
+ PgStat_IOPathOps io_path_ops[BACKEND_NUM_TYPES];
+
PgStat_SLRUStats slru[SLRU_NUM_ELEMENTS];
PgStat_WalStats wal;
@@ -549,6 +558,14 @@ extern void pgstat_database_reset_timestamp_cb(PgStatShared_Common *header, Time
extern bool pgstat_function_flush_cb(PgStat_EntryRef *entry_ref, bool nowait);
+/*
+ * Functions in pgstat_io_ops.c
+ */
+
+extern void pgstat_io_ops_snapshot_cb(void);
+extern void pgstat_io_ops_reset_all_cb(TimestampTz ts);
+
+
/*
* Functions in pgstat_relation.c
*/
--
2.34.1
