On Sun, May 29, 2016 at 1:40 AM, Noah Misch <n...@leadboat.com> wrote: > On Fri, Dec 25, 2015 at 08:08:15PM +0300, Васильев Дмитрий wrote: >> I suddenly found commit ac1d794 gives up to 3 times performance degradation. >> >> I tried to run pgbench -s 1000 -j 48 -c 48 -S -M prepared on 70 CPU-core >> machine: >> commit ac1d794 gives me 363,474 tps >> and previous commit a05dc4d gives me 956,146 >> and master( 3d0c50f ) with revert ac1d794 gives me 969,265 > > [This is a generic notification.] > > The above-described topic is currently a PostgreSQL 9.6 open item. Robert, > since you committed the patch believed to have created it, you own this open > item. If some other commit is more relevant or if this does not belong as a > 9.6 open item, please let us know. Otherwise, please observe the policy on > open item ownership[1] and send a status update within 72 hours of this > message. Include a date for your subsequent status update. Testers may > discover new open items at any time, and I want to plan to get them all fixed > well in advance of shipping 9.6rc1. Consequently, I will appreciate your > efforts toward speedy resolution. Thanks.
So, the reason this is back on the open items list is that Mithun Cy re-reported this problem in: https://www.postgresql.org/message-id/CAD__OuhPmc6XH=wYRm_+Q657yQE88DakN4=ybh2ovefashk...@mail.gmail.com When I saw that, I moved this from CLOSE_WAIT back to open. However, subsequently, Ashutosh Sharma posted this, which suggests (not conclusively) that in fact the problem has been fixed: https://www.postgresql.org/message-id/cae9k0pkfehvq-zg4mh0bz-zt_oe5pas6dauxrcxwx9kevwc...@mail.gmail.com What I *think* is going on here is: - ac1d794 lowered performance - backend_flush_after with a non-zero default lowered performance with a vengeance - 98a64d0 repaired the damage done by ac1d794, or much of it, but Mithun couldn't see it in his benchmarks because backend_flush_after>0 is so bad That could be wrong, but I haven't seen any evidence that it's wrong. So I'm inclined to say we should just move this open item back to the CLOSE_WAIT list (adding a link to this email to explain why we did so). Does that work for you? -- 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