On Sun, Apr 10, 2016 at 1:13 AM, Andres Freund <andres@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.
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.
