mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-09-28 00:01:51 +02:00
pg_stat_wal: Accumulate time as instr_time instead of microseconds
In instr_time.h it is stated that: * When summing multiple measurements, it's recommended to leave the * running sum in instr_time form (ie, use INSTR_TIME_ADD or * INSTR_TIME_ACCUM_DIFF) and convert to a result format only at the end. The reason for that is that converting to microseconds is not cheap, and can loose precision. Therefore this commit changes 'PendingWalStats' to use 'instr_time' instead of 'PgStat_Counter' while accumulating 'wal_write_time' and 'wal_sync_time'. Author: Nazir Bilal Yavuz <byavuz81@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/1feedb83-7aa9-cb4b-5086-598349d3f555@gmail.com
This commit is contained in:
parent
122376f028
commit
ca7b3c4c00
@ -2206,8 +2206,7 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
|
||||
instr_time duration;
|
||||
|
||||
INSTR_TIME_SET_CURRENT(duration);
|
||||
INSTR_TIME_SUBTRACT(duration, start);
|
||||
PendingWalStats.wal_write_time += INSTR_TIME_GET_MICROSEC(duration);
|
||||
INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_write_time, duration, start);
|
||||
}
|
||||
|
||||
PendingWalStats.wal_write++;
|
||||
@ -8204,8 +8203,7 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
|
||||
instr_time duration;
|
||||
|
||||
INSTR_TIME_SET_CURRENT(duration);
|
||||
INSTR_TIME_SUBTRACT(duration, start);
|
||||
PendingWalStats.wal_sync_time += INSTR_TIME_GET_MICROSEC(duration);
|
||||
INSTR_TIME_ACCUM_DIFF(PendingWalStats.wal_sync_time, duration, start);
|
||||
}
|
||||
|
||||
PendingWalStats.wal_sync++;
|
||||
|
@ -469,8 +469,7 @@ BufFileLoadBuffer(BufFile *file)
|
||||
if (track_io_timing)
|
||||
{
|
||||
INSTR_TIME_SET_CURRENT(io_time);
|
||||
INSTR_TIME_SUBTRACT(io_time, io_start);
|
||||
INSTR_TIME_ADD(pgBufferUsage.temp_blk_read_time, io_time);
|
||||
INSTR_TIME_ACCUM_DIFF(pgBufferUsage.temp_blk_read_time, io_time, io_start);
|
||||
}
|
||||
|
||||
/* we choose not to advance curOffset here */
|
||||
@ -544,8 +543,7 @@ BufFileDumpBuffer(BufFile *file)
|
||||
if (track_io_timing)
|
||||
{
|
||||
INSTR_TIME_SET_CURRENT(io_time);
|
||||
INSTR_TIME_SUBTRACT(io_time, io_start);
|
||||
INSTR_TIME_ADD(pgBufferUsage.temp_blk_write_time, io_time);
|
||||
INSTR_TIME_ACCUM_DIFF(pgBufferUsage.temp_blk_write_time, io_time, io_start);
|
||||
}
|
||||
|
||||
file->curOffset += bytestowrite;
|
||||
|
@ -21,7 +21,7 @@
|
||||
#include "executor/instrument.h"
|
||||
|
||||
|
||||
PgStat_WalStats PendingWalStats = {0};
|
||||
PgStat_PendingWalStats PendingWalStats = {0};
|
||||
|
||||
/*
|
||||
* WAL usage counters saved from pgWALUsage at the previous call to
|
||||
@ -70,7 +70,7 @@ bool
|
||||
pgstat_flush_wal(bool nowait)
|
||||
{
|
||||
PgStatShared_Wal *stats_shmem = &pgStatLocal.shmem->wal;
|
||||
WalUsage diff = {0};
|
||||
WalUsage wal_usage_diff = {0};
|
||||
|
||||
Assert(IsUnderPostmaster || !IsPostmasterEnvironment);
|
||||
Assert(pgStatLocal.shmem != NULL &&
|
||||
@ -88,25 +88,26 @@ pgstat_flush_wal(bool nowait)
|
||||
* Calculate how much WAL usage counters were increased by subtracting the
|
||||
* previous counters from the current ones.
|
||||
*/
|
||||
WalUsageAccumDiff(&diff, &pgWalUsage, &prevWalUsage);
|
||||
PendingWalStats.wal_records = diff.wal_records;
|
||||
PendingWalStats.wal_fpi = diff.wal_fpi;
|
||||
PendingWalStats.wal_bytes = diff.wal_bytes;
|
||||
WalUsageAccumDiff(&wal_usage_diff, &pgWalUsage, &prevWalUsage);
|
||||
|
||||
if (!nowait)
|
||||
LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
|
||||
else if (!LWLockConditionalAcquire(&stats_shmem->lock, LW_EXCLUSIVE))
|
||||
return true;
|
||||
|
||||
#define WALSTAT_ACC(fld) stats_shmem->stats.fld += PendingWalStats.fld
|
||||
WALSTAT_ACC(wal_records);
|
||||
WALSTAT_ACC(wal_fpi);
|
||||
WALSTAT_ACC(wal_bytes);
|
||||
WALSTAT_ACC(wal_buffers_full);
|
||||
WALSTAT_ACC(wal_write);
|
||||
WALSTAT_ACC(wal_sync);
|
||||
WALSTAT_ACC(wal_write_time);
|
||||
WALSTAT_ACC(wal_sync_time);
|
||||
#define WALSTAT_ACC(fld, var_to_add) \
|
||||
(stats_shmem->stats.fld += var_to_add.fld)
|
||||
#define WALSTAT_ACC_INSTR_TIME(fld) \
|
||||
(stats_shmem->stats.fld += INSTR_TIME_GET_MICROSEC(PendingWalStats.fld))
|
||||
WALSTAT_ACC(wal_records, wal_usage_diff);
|
||||
WALSTAT_ACC(wal_fpi, wal_usage_diff);
|
||||
WALSTAT_ACC(wal_bytes, wal_usage_diff);
|
||||
WALSTAT_ACC(wal_buffers_full, PendingWalStats);
|
||||
WALSTAT_ACC(wal_write, PendingWalStats);
|
||||
WALSTAT_ACC(wal_sync, PendingWalStats);
|
||||
WALSTAT_ACC_INSTR_TIME(wal_write_time);
|
||||
WALSTAT_ACC_INSTR_TIME(wal_sync_time);
|
||||
#undef WALSTAT_ACC_INSTR_TIME
|
||||
#undef WALSTAT_ACC
|
||||
|
||||
LWLockRelease(&stats_shmem->lock);
|
||||
|
@ -435,6 +435,21 @@ typedef struct PgStat_WalStats
|
||||
TimestampTz stat_reset_timestamp;
|
||||
} PgStat_WalStats;
|
||||
|
||||
/*
|
||||
* This struct stores wal-related durations as instr_time, which makes it
|
||||
* cheaper and easier to accumulate them, by not requiring type
|
||||
* conversions. During stats flush instr_time will be converted into
|
||||
* microseconds.
|
||||
*/
|
||||
typedef struct PgStat_PendingWalStats
|
||||
{
|
||||
PgStat_Counter wal_buffers_full;
|
||||
PgStat_Counter wal_write;
|
||||
PgStat_Counter wal_sync;
|
||||
instr_time wal_write_time;
|
||||
instr_time wal_sync_time;
|
||||
} PgStat_PendingWalStats;
|
||||
|
||||
|
||||
/*
|
||||
* Functions in pgstat.c
|
||||
@ -748,7 +763,7 @@ extern PGDLLIMPORT SessionEndType pgStatSessionEndCause;
|
||||
*/
|
||||
|
||||
/* updated directly by backends and background processes */
|
||||
extern PGDLLIMPORT PgStat_WalStats PendingWalStats;
|
||||
extern PGDLLIMPORT PgStat_PendingWalStats PendingWalStats;
|
||||
|
||||
|
||||
#endif /* PGSTAT_H */
|
||||
|
@ -2053,6 +2053,7 @@ PgStat_Kind
|
||||
PgStat_KindInfo
|
||||
PgStat_LocalState
|
||||
PgStat_PendingDroppedStatsItem
|
||||
PgStat_PendingWalStats
|
||||
PgStat_SLRUStats
|
||||
PgStat_ShmemControl
|
||||
PgStat_Snapshot
|
||||
|
Loading…
Reference in New Issue
Block a user