Sysbench tests on PG12
Hi,
Was running a few sysbench tests in Postgres12.
Sysbench Test Config
oltp-readwrite-custom
Threads - 500
Machine: 16 core 64G
In PG server:
shared_buffers: 16GB
maintenance_work_memory: 16GB
checkpoint_timeout: 1h
max_wal_size: 10GB
wal_sync_method: 'open_sync'
effective_cache_size: 32GB
wal_buffers: -1
wal_compression: on
[image: line-graph (6).png]
Got some qps dips.
Changed fsync and full_page_rewrite to 'off'.
Which helped in avoiding these many long dips in performance:
[image: line-graph (9).png]
But fsync ensures DBMS consistency. So, instead of that can I change a few
other configurations to avoid these inconsistent performance dips ?
Regards,
Subhrajyoti
On Fri, 2021-10-01 at 14:22 +0530, Subhrajyoti Senapati wrote:
Was running a few sysbench tests in Postgres12.
Sysbench Test Config
oltp-readwrite-custom
Threads - 500
Machine: 16 core 64GIn PG server:
shared_buffers: 16GB
maintenance_work_memory: 16GB
checkpoint_timeout: 1h
max_wal_size: 10GB
wal_sync_method: 'open_sync'
effective_cache_size: 32GB
wal_buffers: -1
wal_compression: onGot some qps dips.
Changed fsync and full_page_rewrite to 'off'.
Which helped in avoiding these many long dips in performance:But fsync ensures DBMS consistency. So, instead of that can I change a few other configurations to avoid these inconsistent performance dips ?
Try playing with "bgwriter_flush_after", "checkpoint_flush_after" and "wal_writer_flush_after"
and see if that influences the behavior.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
Thanks Laurenz, will try these flags.
Regards,
Subhrajyoti
On Fri, Oct 1, 2021 at 5:19 PM Laurenz Albe <laurenz.albe@cybertec.at>
wrote:
Show quoted text
On Fri, 2021-10-01 at 14:22 +0530, Subhrajyoti Senapati wrote:
Was running a few sysbench tests in Postgres12.
Sysbench Test Config
oltp-readwrite-custom
Threads - 500
Machine: 16 core 64GIn PG server:
shared_buffers: 16GB
maintenance_work_memory: 16GB
checkpoint_timeout: 1h
max_wal_size: 10GB
wal_sync_method: 'open_sync'
effective_cache_size: 32GB
wal_buffers: -1
wal_compression: onGot some qps dips.
Changed fsync and full_page_rewrite to 'off'.
Which helped in avoiding these many long dips in performance:But fsync ensures DBMS consistency. So, instead of that can I change a
few other configurations to avoid these inconsistent performance dips ?
Try playing with "bgwriter_flush_after", "checkpoint_flush_after" and
"wal_writer_flush_after"
and see if that influences the behavior.Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com