On Sun, Apr 10, 2016 at 11:10 AM, Alexander Korotkov < a.korot...@postgrespro.ru> wrote:
> On Sun, Apr 10, 2016 at 7:26 AM, Amit Kapila <amit.kapil...@gmail.com> > wrote: > >> On Sun, Apr 10, 2016 at 1:13 AM, Andres Freund <and...@anarazel.de> >> wrote: >> >>> On 2016-04-09 22:38:31 +0300, Alexander Korotkov wrote: >>> > There are results with 5364b357 reverted. >>> >>> >> What exactly is this test? >> I think assuming it is a read-only -M prepared pgbench run where data >> fits in shared buffers. However if you can share exact details, then I can >> try the similar test. >> > > Yes, the test is: > > pgbench -s 1000 -c $clients -j 100 -M prepared -S -T 300 > (shared_buffers=24GB) > > >> >>> Crazy that this has such a negative impact. Amit, can you reproduce >>> that? >> >> >> I will try it. >> > > Good. > Okay, I have done some performance testing of read-only tests with configuration suggested by you to see the impact pin_unpin - latest version of pin unpin patch on top of HEAD. pin_unpin_clog_32 - pin_unpin + change clog buffers to 32 Client_Count/Patch_ver 64 128 pin_unpin 330280 133586 pin_unpin_clog_32 388244 132388 This shows that at 64 client count, the performance is better with 32 clog buffers. However, I think this is more attributed towards the fact that contention seems to shifted to procarraylock as to an extent indicated in Alexandar's mail. I will try once with cache the snapshot patch as well and with clog buffers as 64. With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
