Hi,
On 02/03/2018 01:05 PM, Tomas Vondra wrote:
> Hi,
>
> ...
>
> In this round of tests I've disabled parallelism. Based on
> discussion with Andres I've decided to repeat the tests with parallel
> queries enabled - that's running now, and will take some time to
> complete.
>
And here are the results with parallelism enabled - same machines, but
with max_parallel_workers_per_gather > 0. Based on discussions and
Andres' FOSDEM talk I somehow expected more significant JIT benefits in
the parallel case, but the results are pretty much exactly the same
(modulo speedup thanks to parallelism, of course).
In fact, the JIT impact is much noisier with parallelism enabled, for
some reason, with regressions where there were no measurable regressions
before (particularly for the 10GB case).
That is not to say we shouldn't be doing JIT, or that Andres did not
observe the speedups/benefits he mentioned during the talk - I have no
trouble believing it depends on queries, and DBT-3 may not match that.
I don't plan doing any further benchmarks on this patch series unless
someone requests that (possibly with ideas what to focus on). I'll keep
looking at the patch, of course. I've seen some build issues, so I'll
try finding more details.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
