From: | Greg Smith <greg(at)2ndQuadrant(dot)com> |
---|---|
To: | Jeff Davis <pgsql(at)j-davis(dot)com> |
Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)2ndquadrant(dot)com>, Florian Pflug <fgp(at)phlo(dot)org>, Ants Aasma <ants(dot)aasma(at)eesti(dot)ee>, Robert Haas <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Bruce Momjian <bruce(at)momjian(dot)us>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
Subject: | Re: Substituting Checksum Algorithm (was: Enabling Checksums) |
Date: | 2013-04-26 20:40:20 |
Message-ID: | 517AE634.9060302@2ndQuadrant.com |
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Lists: | pgsql-hackers |
On 4/26/13 3:57 PM, Jeff Davis wrote:
> The second patch adds the configure-time check for the right
> compilation flags, and uses them when compiling checksum.c. I
> called the new variable CFLAGS_EXTRA, for lack of a better idea,
> so feel free to come up with a new name. It doesn't check for, or
> use, -msse4.1, but that can be specified by the user by
> configuring with CFLAGS_EXTRA="-msse4.1".
Thank you, that is the last piece I was looking at but couldn't nail
down on my own. With that I should be able to duplicate both the
slicing by 8 CRC speedup Ants sent over (which also expected some
optimization changes) and trying something FNV based this weekend.
I think I need to do two baselines: master without checksums, and
master with extra optimizations but still without checksums. It may be
the case that using better compile time optimizations gives a general
speedup that's worth considering regardless. The optimizations seem to
have a very significant impact on the checksum feature, but I'd like to
quantify how they change the code a little bit before even getting into
that.
--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
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