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Track IO times in pg_stat_io

Browse Source 
a9c70b46db and 8aaa04b32S added counting of IO operations to a new view,
pg_stat_io. Now, add IO timing for reads, writes, extends, and fsyncs to
pg_stat_io as well.

This combines the tracking for pgBufferUsage with the tracking for pg_stat_io
into a new function pgstat_count_io_op_time(). This should make it a bit
easier to avoid the somewhat costly instr_time conversion done for
pgBufferUsage.

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/flat/CAAKRu_ay5iKmnbXZ3DsauViF3eMxu4m1oNnJXqV_HyqYeg55Ww%40mail.gmail.com
This commit is contained in:
Andres Freund
2023-04-07 16:05:26 -07:00
parent 1c453cfd89
commit ac8d53dae5
11 changed files with 276 additions and 108 deletions
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64
src/backend/utils/adt/pgstatfuncs.c
View File

@ -1252,17 +1252,22 @@ pg_stat_get_buf_alloc(PG_FUNCTION_ARGS)
*/
typedef enum io_stat_col
{
IO_COL_INVALID = -1,
IO_COL_BACKEND_TYPE,
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_HITS,
IO_COL_EVICTIONS,
IO_COL_REUSES,
IO_COL_FSYNCS,
IO_COL_FSYNC_TIME,
IO_COL_RESET_TIME,
IO_NUM_COLUMNS,
} io_stat_col;
@ -1296,6 +1301,38 @@ pgstat_get_io_op_index(IOOp io_op)
pg_unreachable();
}
/*
* Get the number of the column containing IO times for the specified IOOp.
* This function encodes our assumption that IO time for an IOOp is displayed
* in the view in the column directly after the IOOp counts. If an op has no
* associated time, IO_COL_INVALID is returned.
*/
static io_stat_col
pgstat_get_io_time_index(IOOp io_op)
{
switch (io_op)
{
case IOOP_READ:
case IOOP_WRITE:
case IOOP_EXTEND:
case IOOP_FSYNC:
return pgstat_get_io_op_index(io_op) + 1;
case IOOP_EVICT:
case IOOP_HIT:
case IOOP_REUSE:
return IO_COL_INVALID;
}
elog(ERROR, "unrecognized IOOp value: %d", io_op);
pg_unreachable();
}
static inline double
pg_stat_us_to_ms(PgStat_Counter val_ms)
{
return val_ms * (double) 0.001;
}
Datum
pg_stat_get_io(PG_FUNCTION_ARGS)
{
@ -1363,20 +1400,37 @@ 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);
int op_idx = pgstat_get_io_op_index(io_op);
int time_idx = pgstat_get_io_time_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))
{
PgStat_Counter count =
bktype_stats->counts[io_obj][io_context][io_op];
if (nulls[col_idx])
values[op_idx] = Int64GetDatum(count);
}
else
nulls[op_idx] = true;
/* not every operation is timed */
if (time_idx == IO_COL_INVALID)
continue;
values[col_idx] =
Int64GetDatum(bktype_stats->data[io_obj][io_context][io_op]);
if (!nulls[op_idx])
{
PgStat_Counter time =
bktype_stats->times[io_obj][io_context][io_op];
values[time_idx] = Float8GetDatum(pg_stat_us_to_ms(time));
}
else
nulls[time_idx] = true;
}
tuplestore_putvalues(rsinfo->setResult, rsinfo->setDesc,