From: | Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr> |
---|---|
To: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> |
Cc: | hironobu(at)interdb(dot)jp, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
Subject: | Re: pgbench - add pseudo-random permutation function |
Date: | 2018-09-26 11:20:49 |
Message-ID: | alpine.DEB.2.21.1809261305270.22248@lancre |
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Thread: | |
Lists: | pgsql-hackers |
Hello,
> That is necessary because most people consume PostgreSQL through
> packages from distributions that have to work on an Athlon II or
> whatever, so we can't just use -msse4.2 for every translation unit.
> So it becomes our job to isolate small bits of code that use newer
> instructions, if it's really worth the effort to do that, and supply
> our own runtime checks and provide a fallback.
Ok. That was my understanding so as to improve the portability/performance
compromise. I do not think that pgbench is worth the effort on this
particular point.
> [...] None of that seems worth it for something like this.
Indeed.
So, am I right to deducing that you are satisfied with the current status
of the patch, with the nbits implementation either based on popcount (v4)
or clz (v5) compiler intrinsics? I think that the clz option is better.
--
Fabien.
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