Re: JIT compiling with LLVM v12.2

From: Andres Freund <andres(at)anarazel(dot)de>
To: Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: JIT compiling with LLVM v12.2
Date: 2018-03-30 17:38:08
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On March 30, 2018 10:04:25 AM PDT, Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru> wrote:
>On 30.03.2018 18:54, Andres Freund wrote:
>> On 2018-03-30 15:12:05 +0300, Konstantin Knizhnik wrote:
>>> I have repeated performance tests at my computer and find out some
>>> regression comparing with previous JIT version.
>>> Previously JIT provides about 2 times improvement at TPC-H Q1. Now
>>> difference is reduced to 1.4 without parallel execution and 1.3 with
>>> parallel execution:
>> Huh. That's the same computer you did the tests on?
>> There shouldn't have been any, I'll check it out.
>> - Andres
>Yes, it is the same computer.
>But sorry, may be it is false alarm.
>I noticed that the time of normal (non-jit) query execution was also
>faster in the past: for parallel execution 6549 vs. 7550 now, for
>non-parallel execution 20075 vs. 25100.
>I do not know whether this difference is caused by some changes in
>Postgres committed since this time (end of January) or just because of
>different layout of data in memory.

A brief attempt at bisecting would be good. That's quite the regression. Possibly it's OS related though. Meltdown / Spectre?

Sent from my Android device with K-9 Mail. Please excuse my brevity.

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Jerry Sievers 2018-03-30 17:43:03 Re: Speedup of relation deletes during recovery
Previous Message Andres Freund 2018-03-30 17:36:27 Re: [HACKERS] logical decoding of two-phase transactions