From: | Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)com> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Windows warnings from VS 2017 |
Date: | 2017-09-22 11:37:32 |
Message-ID: | c7e5532b-5db0-cab5-cbec-0c8c80b1035e@2ndQuadrant.com |
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Lists: | pgsql-hackers |
On 09/21/2017 09:41 PM, Andres Freund wrote:
> On 2017-09-21 09:30:31 -0400, Tom Lane wrote:
>> Andrew Dunstan <andrew(dot)dunstan(at)2ndquadrant(dot)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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