Re: 10x faster sort performance on Skylake CPU vs Ivy Bridge

From: Peter Geoghegan <pg(at)bowt(dot)ie>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Felix Geisendörfer <felix(at)felixge(dot)de>, postgres performance list <pgsql-performance(at)postgresql(dot)org>
Subject: Re: 10x faster sort performance on Skylake CPU vs Ivy Bridge
Date: 2017-08-25 15:43:49
Message-ID: CAH2-WznaO1jsm1MsnpwAp4PArxP9NDhV-zHMgTy8sG6_OMwN7A@mail.gmail.com
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On Fri, Aug 25, 2017 at 8:07 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I doubt this is a hardware issue, it's more likely that you're comparing
> apples and oranges. The first theory that springs to mind is that the
> sort keys are strings and you're using C locale on the faster machine but
> some non-C locale on the slower. strcoll() is pretty darn expensive
> compared to strcmp() :-(

strcoll() is very noticeably slower on macOS, too.

--
Peter Geoghegan

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