From 34c70c7ac4926495b7ab5ebfe748704313a4c822 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 14 Dec 2010 09:25:25 -0500
Subject: [PATCH] Instrument checkpoint sync calls.
Greg Smith, reviewed by Jeff Janes
---
src/backend/access/transam/xlog.c | 41 ++++++++++++++++++++++++++-----
src/backend/storage/smgr/md.c | 37 ++++++++++++++++++++++++++++
src/include/access/xlog.h | 7 ++++++
3 files changed, 79 insertions(+), 6 deletions(-)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 49764581049..b49b933de3e 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6953,10 +6953,15 @@ LogCheckpointEnd(bool restartpoint)
{
long write_secs,
sync_secs,
- total_secs;
+ total_secs,
+ longest_secs,
+ average_secs;
int write_usecs,
sync_usecs,
- total_usecs;
+ total_usecs,
+ longest_usecs,
+ average_usecs;
+ uint64 average_sync_time;
CheckpointStats.ckpt_end_t = GetCurrentTimestamp();
@@ -6972,18 +6977,39 @@ LogCheckpointEnd(bool restartpoint)
CheckpointStats.ckpt_sync_end_t,
&sync_secs, &sync_usecs);
+ /*
+ * Timing values returned from CheckpointStats are in microseconds.
+ * Convert to the second plus microsecond form that TimestampDifference
+ * returns for homogeneous printing.
+ */
+ longest_secs = (long) (CheckpointStats.ckpt_longest_sync / 1000000);
+ longest_usecs = CheckpointStats.ckpt_longest_sync -
+ (uint64) longest_secs * 1000000;
+
+ average_sync_time = 0;
+ if (CheckpointStats.ckpt_sync_rels > 0)
+ average_sync_time = CheckpointStats.ckpt_agg_sync_time /
+ CheckpointStats.ckpt_sync_rels;
+ average_secs = (long) (average_sync_time / 1000000);
+ average_usecs = average_sync_time - (uint64) average_secs * 1000000;
+
if (restartpoint)
elog(LOG, "restartpoint complete: wrote %d buffers (%.1f%%); "
- "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s",
+ "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; "
+ "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s",
CheckpointStats.ckpt_bufs_written,
(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
write_secs, write_usecs / 1000,
sync_secs, sync_usecs / 1000,
- total_secs, total_usecs / 1000);
+ total_secs, total_usecs / 1000,
+ CheckpointStats.ckpt_sync_rels,
+ longest_secs, longest_usecs / 1000,
+ average_secs, average_usecs / 1000);
else
elog(LOG, "checkpoint complete: wrote %d buffers (%.1f%%); "
"%d transaction log file(s) added, %d removed, %d recycled; "
- "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s",
+ "write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s; "
+ "sync files=%d, longest=%ld.%03d s, average=%ld.%03d s",
CheckpointStats.ckpt_bufs_written,
(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers,
CheckpointStats.ckpt_segs_added,
@@ -6991,7 +7017,10 @@ LogCheckpointEnd(bool restartpoint)
CheckpointStats.ckpt_segs_recycled,
write_secs, write_usecs / 1000,
sync_secs, sync_usecs / 1000,
- total_secs, total_usecs / 1000);
+ total_secs, total_usecs / 1000,
+ CheckpointStats.ckpt_sync_rels,
+ longest_secs, longest_usecs / 1000,
+ average_secs, average_usecs / 1000);
}
/*
diff --git a/src/backend/storage/smgr/md.c b/src/backend/storage/smgr/md.c
index 604db218eeb..944eed83c5a 100644
--- a/src/backend/storage/smgr/md.c
+++ b/src/backend/storage/smgr/md.c
@@ -20,6 +20,7 @@
#include "catalog/catalog.h"
#include "miscadmin.h"
+#include "portability/instr_time.h"
#include "postmaster/bgwriter.h"
#include "storage/fd.h"
#include "storage/bufmgr.h"
@@ -927,6 +928,15 @@ mdsync(void)
PendingOperationEntry *entry;
int absorb_counter;
+ /* Statistics on sync times */
+ int processed = 0;
+ instr_time sync_start,
+ sync_end,
+ sync_diff;
+ uint64 elapsed;
+ uint64 longest = 0;
+ uint64 total_elapsed = 0;
+
/*
* This is only called during checkpoints, and checkpoints should only
* occur in processes that have created a pendingOpsTable.
@@ -1069,9 +1079,31 @@ mdsync(void)
seg = _mdfd_getseg(reln, entry->tag.forknum,
entry->tag.segno * ((BlockNumber) RELSEG_SIZE),
false, EXTENSION_RETURN_NULL);
+
+ if (log_checkpoints)
+ INSTR_TIME_SET_CURRENT(sync_start);
+ else
+ INSTR_TIME_SET_ZERO(sync_start);
+
if (seg != NULL &&
FileSync(seg->mdfd_vfd) >= 0)
+ {
+ if (log_checkpoints && (! INSTR_TIME_IS_ZERO(sync_start)))
+ {
+ INSTR_TIME_SET_CURRENT(sync_end);
+ sync_diff = sync_end;
+ INSTR_TIME_SUBTRACT(sync_diff, sync_start);
+ elapsed = INSTR_TIME_GET_MICROSEC(sync_diff);
+ if (elapsed > longest)
+ longest = elapsed;
+ total_elapsed += elapsed;
+ processed++;
+ elog(DEBUG1, "checkpoint sync: number=%d file=%s time=%.3f msec",
+ processed, FilePathName(seg->mdfd_vfd), (double) elapsed / 1000);
+ }
+
break; /* success; break out of retry loop */
+ }
/*
* XXX is there any point in allowing more than one retry?
@@ -1113,6 +1145,11 @@ mdsync(void)
elog(ERROR, "pendingOpsTable corrupted");
} /* end loop over hashtable entries */
+ /* Return sync performance metrics for report at checkpoint end */
+ CheckpointStats.ckpt_sync_rels = processed;
+ CheckpointStats.ckpt_longest_sync = longest;
+ CheckpointStats.ckpt_agg_sync_time = total_elapsed;
+
/* Flag successful completion of mdsync */
mdsync_in_progress = false;
}
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index fa7ae2ac126..e9d8d15814a 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -257,6 +257,13 @@ typedef struct CheckpointStatsData
int ckpt_segs_added; /* # of new xlog segments created */
int ckpt_segs_removed; /* # of xlog segments deleted */
int ckpt_segs_recycled; /* # of xlog segments recycled */
+
+ int ckpt_sync_rels; /* # of relations synced */
+ uint64 ckpt_longest_sync; /* Longest sync for one relation */
+ uint64 ckpt_agg_sync_time; /* The sum of all the individual sync
+ * times, which is not necessarily the
+ * same as the total elapsed time for
+ * the entire sync phase. */
} CheckpointStatsData;
extern CheckpointStatsData CheckpointStats;
--
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