On Fri, Sep 19, 2014 at 6:58 PM, Mark Kirkwood <mark.kirkwood@xxxxxxxxxxxxxxx> wrote: > On 19/09/14 19:24, Mkrtchyan, Tigran wrote: >> >> >> >> ----- Original Message ----- >>> >>> From: "Mark Kirkwood" <mark.kirkwood@xxxxxxxxxxxxxxx> >>> To: "Tigran Mkrtchyan" <tigran.mkrtchyan@xxxxxxx> >>> Cc: "Merlin Moncure" <mmoncure@xxxxxxxxx>, "postgres performance list" >>> <pgsql-performance@xxxxxxxxxxxxxx> >>> Sent: Friday, September 19, 2014 8:26:27 AM >>> Subject: Re: postgres 9.3 vs. 9.4 >>> >>> On 19/09/14 17:53, Mkrtchyan, Tigran wrote: >>>> >>>> >>>> >>>> ----- Original Message ----- >>>>> >>>>> From: "Mark Kirkwood" <mark.kirkwood@xxxxxxxxxxxxxxx> >>> >>> >>>>> Further to the confusion, here's my 9.3 vs 9.4 on two M550 (one for 9.3 >>>>> one for 9.4), see below for results. >>>>> >>>>> I'm running xfs on them with trim/discard enabled: >>>>> >>>>> $ mount|grep pg >>>>> /dev/sdd4 on /mnt/pg94 type xfs (rw,discard) >>>>> /dev/sdc4 on /mnt/pg93 type xfs (rw,discard) >>>>> >>>>> >>>>> I'm *not* seeing any significant difference between 9.3 and 9.4, and >>>>> the >>>>> numbers are both about 2x your best number, which is food for thought >>>>> (those P320's should toast my M550 for write performance...). >>>> >>>> >>>> cool! any details on OS and other options? I still get the same numbers >>>> as before. >>>> >>> >>> Sorry, Ubuntu 14.04 on a single socket i7 3.4 Ghz, 16G (i.e my >>> workstation). >>> >>> I saw the suggestion that Didier made to run 9.3 on the SSD that you >>> were using for 9.4, and see if it suddenly goes slow - then we'd know >>> it's something about the disk (or filesystem/mount options). Can you >>> test this? >> >> >> >> swapping the disks did not change the results. >> >> > > Do you mean that 9.3 was still faster using the disk that 9.4 had used? If > so that strongly suggests that there is something you have configured > differently in the 9.4 installation [1]. Not wanting to sound mean - but it > is really easy to accidentally connect to the wrong instance when there are > two on the same box (ahem, yes , done it myself). So perhaps another look at > the 9.4 vs 9.3 setup (or even posti the config files postgresql.conf + > postgresql.auto.conf for 9.4 here). Huh. Where did the 9.4 build come from? I wonder if there are some debugging options set. Can you check 9.4 pg_settings for value of"debug_assertions"? If it's set true, you might want to consider hand compiling postgres until 9.4 is released... merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
