116 lines
3.2 KiB
C
116 lines
3.2 KiB
C
/* -------------------------------------------------------------------------
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*
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* pgstat_bgwriter.c
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* Implementation of bgwriter statistics.
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*
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* This file contains the implementation of bgwriter statistics. It is kept
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* separate from pgstat.c to enforce the line between the statistics access /
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* storage implementation and the details about individual types of
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* statistics.
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*
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* Copyright (c) 2001-2023, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/backend/utils/activity/pgstat_bgwriter.c
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* -------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "utils/pgstat_internal.h"
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PgStat_BgWriterStats PendingBgWriterStats = {0};
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/*
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* Report bgwriter and IO statistics
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*/
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void
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pgstat_report_bgwriter(void)
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{
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PgStatShared_BgWriter *stats_shmem = &pgStatLocal.shmem->bgwriter;
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static const PgStat_BgWriterStats all_zeroes;
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Assert(!pgStatLocal.shmem->is_shutdown);
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pgstat_assert_is_up();
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/*
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* This function can be called even if nothing at all has happened. In
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* this case, avoid unnecessarily modifying the stats entry.
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*/
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if (memcmp(&PendingBgWriterStats, &all_zeroes, sizeof(all_zeroes)) == 0)
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return;
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pgstat_begin_changecount_write(&stats_shmem->changecount);
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#define BGWRITER_ACC(fld) stats_shmem->stats.fld += PendingBgWriterStats.fld
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BGWRITER_ACC(buf_written_clean);
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BGWRITER_ACC(maxwritten_clean);
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BGWRITER_ACC(buf_alloc);
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#undef BGWRITER_ACC
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pgstat_end_changecount_write(&stats_shmem->changecount);
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/*
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* Clear out the statistics buffer, so it can be re-used.
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*/
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MemSet(&PendingBgWriterStats, 0, sizeof(PendingBgWriterStats));
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/*
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* Report IO statistics
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*/
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pgstat_flush_io(false);
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}
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/*
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* Support function for the SQL-callable pgstat* functions. Returns
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* a pointer to the bgwriter statistics struct.
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*/
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PgStat_BgWriterStats *
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pgstat_fetch_stat_bgwriter(void)
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{
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pgstat_snapshot_fixed(PGSTAT_KIND_BGWRITER);
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return &pgStatLocal.snapshot.bgwriter;
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}
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void
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pgstat_bgwriter_reset_all_cb(TimestampTz ts)
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{
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PgStatShared_BgWriter *stats_shmem = &pgStatLocal.shmem->bgwriter;
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/* see explanation above PgStatShared_BgWriter for the reset protocol */
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LWLockAcquire(&stats_shmem->lock, LW_EXCLUSIVE);
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pgstat_copy_changecounted_stats(&stats_shmem->reset_offset,
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&stats_shmem->stats,
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sizeof(stats_shmem->stats),
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&stats_shmem->changecount);
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stats_shmem->stats.stat_reset_timestamp = ts;
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LWLockRelease(&stats_shmem->lock);
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}
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void
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pgstat_bgwriter_snapshot_cb(void)
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{
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PgStatShared_BgWriter *stats_shmem = &pgStatLocal.shmem->bgwriter;
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PgStat_BgWriterStats *reset_offset = &stats_shmem->reset_offset;
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PgStat_BgWriterStats reset;
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pgstat_copy_changecounted_stats(&pgStatLocal.snapshot.bgwriter,
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&stats_shmem->stats,
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sizeof(stats_shmem->stats),
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&stats_shmem->changecount);
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LWLockAcquire(&stats_shmem->lock, LW_SHARED);
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memcpy(&reset, reset_offset, sizeof(stats_shmem->stats));
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LWLockRelease(&stats_shmem->lock);
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/* compensate by reset offsets */
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#define BGWRITER_COMP(fld) pgStatLocal.snapshot.bgwriter.fld -= reset.fld;
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BGWRITER_COMP(buf_written_clean);
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BGWRITER_COMP(maxwritten_clean);
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BGWRITER_COMP(buf_alloc);
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#undef BGWRITER_COMP
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}
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