RE: [Proposal] Add accumulated statistics for wait event

On Sat, Feb 1, 2020 at 5:50 AM, Pavel Stehule wrote:
> today I run 120 5minutes pgbench tests to measure impact of this patch. Result is attached.
...
> Thanks to Tomas Vondra and 2ndq for hw for testing

Thank you for doing a lot of these benchmarks!

> The result is interesting - when I run pgbench in R/W mode, then I got +/- 1% changes in performance. Isn't important if
> tracking time is active or not (tested on Linux). In this mode the new code is not on critical path.

It seems performance difference is big in case of read only tests. The reason is that write time is relatively longer than the
processing time of the logic I added in the patch.

> Looks so for higher scale than 5 and higher number of users 50 the results are not too much stable (for read only tests - I
> repeated tests) and there overhead is about 10% from 60K tps to 55Ktps - maybe I hit a hw limits (it running with 4CPU)

Yes, I suspect some other bottlenecks may be happened and it causes the results unstable. However, it may be better to
investigate what is actually happened and why performance is increased/decreased for over 10%. I will inspect it.

Also I attach v5 patches which corresponds to other committed patches.

--
Yoshikazu Imai