On Sat, Apr 9, 2016 at 10:49 PM, Andres Freund <andres@anarazel.de> wrote:
On April 9, 2016 12:43:03 PM PDT, Andres Freund <andres@anarazel.de> wrote: >On 2016-04-09 22:38:31 +0300, Alexander Korotkov wrote: >> There are results with 5364b357 reverted. > >Crazy that this has such a negative impact. Amit, can you reproduce >that? Alexander, I guess for r/w workload 5364b357 is a benefit on that >machine as well?
How sure are you about these measurements?
I'm pretty sure. I've retried it multiple times by hand before re-run the script.
Because there really shouldn't be clog lookups one a steady state is reached...
Hm... I'm also surprised. There shouldn't be clog lookups once hint bits are set.
I also tried to run perf top during pgbench and get some interesting results.
Very surprising. It appears that after 5364b357, GetSnapshotData consumes more time. But I can't see anything depending on clog buffers in GetSnapshotData code...
------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company