Hi Fabien, 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? 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. Reading kernel sources trying to understand some more of the performance impact. Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
