On 19/09/14 08:32, Merlin Moncure wrote:
On Thu, Sep 18, 2014 at 4:58 AM, Mkrtchyan, Tigran <tigran.mkrtchyan@xxxxxxx> wrote:9.3.5: 0.035940 END; 9.4beta2: 0.957854 END;time being spent on 'END' is definitely suggesting i/o related issues. This is making me very skeptical that postgres is the source of the problem. I also thing synchronous_commit is not set properly on the new instance (or possibly there is a bug or some such). Can you verify via: select * from pg_settings where name = 'synchronous_commit'; on both servers?
Yes, does look suspicious. It *could* be that the 9.4 case is getting unlucky and checkpointing just before the end of the 60s run, and 9.3 isn't.
What is iowait? For pci-e SSD, these drives don't seem very fast...
These look like rebranded Micron P320's and should be extremely fast...However I note that my Crucial/Micron M550's are very fast for most writes *but* are much slower for sync writes (and fsync) that happen at commit...
Cheers Mark -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
