On Sun, Apr 17, 2016 at 7:32 PM, Amit Kapila <amit.kapil...@gmail.com> wrote:
> On Thu, Apr 14, 2016 at 8:05 AM, Andres Freund <and...@anarazel.de> wrote: > > > > On 2016-04-14 07:59:07 +0530, Amit Kapila wrote: > > > What you want to see by prewarming? > > > > Prewarming appears to greatly reduce the per-run variance on that > > machine, making it a lot easier to get meaningful results. > > > > I think you are referring the tests done by Robert on power-8 m/c, but the > performance results I have reported were on intel x86. In last two days, I > have spent quite some effort to do the performance testing of this patch > with pre-warming by using the same query [1] as used by Robert in his > tests. The tests are done such that first it start server, pre-warms the > relations, ran read-only test, stop server, again repeat this for next test. > What did you include into single run: test of single version (HEAD or Patch) or test of both of them? > I have observed that the variance in run-to-run performance still occurs > especially at higher client count (128). Below are results for 128 client > count both when the tests ran first with patch and then with HEAD and vice > versa. > > Test-1 > ---------- > client count - 128 (basically -c 128 -j 128) > > first tests ran with patch and then with HEAD > > Patch_ver/Runs HEAD (commit -70715e6a) Patch > Run-1 156748 174640 > Run-2 151352 150115 > Run-3 177940 165269 > > > Test-2 > ---------- > client count - 128 (basically -c 128 -j 128) > > first tests ran with HEAD and then with patch > > Patch_ver/Runs HEAD (commit -70715e6a) Patch > Run-1 173063 151282 > Run-2 173187 140676 > Run-3 177046 166726 > > I think this patch (padding pgxact) certainly is beneficial as reported > above thread. At very high client count some variation in performance is > observed with and without patch, but I feel in general it is a win. > So, what hardware did you use for these tests: power-8 or x86? How long was single run? Per-run variation seems quite high. It also seems that it depends on which version runs first. But that could be a coincidence. ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
