Re: JIT compiling with LLVM v12.2

From: Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: JIT compiling with LLVM v12.2
Date: 2018-03-30 17:04:25
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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 the
>> 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.
But JIT performance improvement is almost the same in both cases: 1.493
vs 1.434 now.

Konstantin Knizhnik
Postgres Professional:
The Russian Postgres Company

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