On 2016-02-22 11:05:20 -0500, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > Interesting. That doesn't reflect my own tests, even on rotating media, > > at all. I wonder if it's related to: > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=23d0127096cb91cb6d354bdc71bd88a7bae3a1d5 > > > If you use your 12.04 kernel, that'd not be fixed. Which might be a > > reason to do it as you suggest. > > Hmm ... that kernel commit is less than 4 months old. Would it be > reflected in *any* production kernels yet?
Probably not - so far I though it mainly has some performance benefits on relatively extreme workloads; where without the patch, flushing still is better performancewise than not flushing. But in the scenario Fabien has brought up it seems quite possible that sync_file_range emitting "storage cache flush" instructions, could explain the rather large performance difference between his and my experiments. Regards, Andres -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers