From: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>
Subject: Re: Windows warnings from VS 2017
To: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: Haribabu Kommi <kommi.haribabu@gmail.com>,
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Date: Fri, 22 Sep 2017 07:37:32 -0400
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On 09/21/2017 09:41 PM, Andres Freund wrote:
> On 2017-09-21 09:30:31 -0400, Tom Lane wrote:
>> Andrew Dunstan <andrew.dunstan@2ndquadrant.com> writes:
>>> The speed of memset is hardly going to be the dominating factor in a
>>> 'CREATE DATABASE' command, so we could certainly afford to change to
>>> plain memset calls here.
>> Another thought is that it may be time for our decennial debate about
>> whether MemSet is worth the electrons it's printed on.  I continue to
>> think that any modern compiler+libc ought to do an equivalent or better
>> optimization given just a plain memset().  If that seems to be true
>> for recent MSVC, we could consider putting an #if into c.h to define
>> MemSet as just memset for MSVC.  Maybe later that could be extended
>> to other compilers.
> +many. glibc's memset is nearly an order of magnitude faster than MemSet
> on my machine for medium+ length copies, and still 3-4 four times ~100
> bytes. And both gcc and clang optimize way the memcpy entirely when the
> length is a fixed short length.


Perhaps we need some sort of small benchmark program that we can run on
a representative set of platforms? I presume if you can make that
assertion you already have something along those lines?

cheers

andrew


-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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