Re: checkpointer continuous flushing
От | Fabien COELHO |
---|---|
Тема | Re: checkpointer continuous flushing |
Дата | |
Msg-id | alpine.DEB.2.10.1601160843440.18181@sto обсуждение исходный текст |
Ответ на | Re: checkpointer continuous flushing (Andres Freund <andres@anarazel.de>) |
Ответы |
Re: checkpointer continuous flushing
|
Список | pgsql-hackers |
> Hi Fabien, Hello Tomas. > On 2016-01-11 14:45:16 +0100, Andres Freund wrote: >> I measured it in a different number of cases, both on SSDs and spinning >> rust. I just reproduced it with: >> >> postgres-ckpt14 \ >> -D /srv/temp/pgdev-dev-800/ \ >> -c maintenance_work_mem=2GB \ >> -c fsync=on \ >> -c synchronous_commit=off \ >> -c shared_buffers=2GB \ >> -c wal_level=hot_standby \ >> -c max_wal_senders=10 \ >> -c max_wal_size=100GB \ >> -c checkpoint_timeout=30s > > What kernel, filesystem and filesystem option did you measure with? Andres did these measures, not me, so I do not know. > I was/am using ext4, and it turns out that, when abling flushing, the > results are hugely dependant on barriers=on/off, with the latter making > flushing rather advantageous. Additionally data=ordered/writeback makes > measureable difference too. These are very interesting tests, I'm looking forward to have a look at the results. The fact that these options change performance is expected. Personnaly the test I submitted on the thread used ext4 with default mount options plus "relatime". If I had a choice, I would tend to take the safest options, because the point of a database is to keep data safe. That's why I'm not found of the "synchronous_commit=off" chosen above. > Reading kernel sources trying to understand some more of the performance > impact. Wow! -- Fabien.
В списке pgsql-hackers по дате отправления: