On Sat, Feb 4, 2012 at 11:59 AM, Greg Smith <g...@2ndquadrant.com> wrote: > On 01/24/2012 08:58 AM, Robert Haas wrote: >> >> One somewhat odd thing about these numbers is that, on permanent >> tables, all of the patches seemed to show regressions vs. master in >> single-client throughput. That's a slightly difficult result to >> believe, though, so it's probably a testing artifact of some kind. > > It looks like you may have run the ones against master first, then the ones > applying various patches. The one test artifact I have to be very careful > to avoid in that situation is that later files on the physical disk are > slower than earlier ones. There's a >30% differences between the fastest > part of a regular hard drive, the logical beginning, and its end. Multiple > test runs tend to creep forward onto later sections of disk, and be biased > toward the earlier run in that case. To eliminate that bias when it gets > bad, I normally either a) run each test 3 times, interleaved, or b) rebuild > the filesystem in between each initdb. > > I'm not sure that's the problem you're running into, but it's the only one > I've been hit by that matches the suspicious part of your results.
I don't think that's it, because tests on various branches were interleaved; moreover, I don't believe master was the first one in the rotation. I think I had then in alphabetical order by branch name, actually. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
