Re: Enabling Checksums

From: Ants Aasma <ants(at)cybertec(dot)at>
To: Ants Aasma <ants(at)cybertec(dot)at>
Cc: Jeff Davis <pgsql(at)j-davis(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Greg Smith <greg(at)2ndquadrant(dot)com>, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Enabling Checksums
Date: 2013-04-09 02:35:16
Message-ID: CA+CSw_s=XptYYott1oZLTgxgRfndBMCuVzCrTRNqt7GM47Yy_w@mail.gmail.com
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On Fri, Apr 5, 2013 at 9:39 PM, Ants Aasma <ants(at)cybertec(dot)at> wrote:
> Unless somebody tells me not to waste my time I'll go ahead and come
> up with a workable patch by Monday.

And here you go. I decided to be verbose with the comments as it's
easier to delete a comment to write one. I also left in a huge jumble
of macros to calculate the contents of a helper var during compile
time. This can easily be replaced with the calculated values once we
settle on specific parameters.

Currently only x86-64 is implemented. 32bit x86 would be mostly a
copy-and-paste job, replacing 64bit pointer registers with 32bit ones.
For other platforms the simplest way would be to use a vectorizing
compiler on the generic variant. -funroll-loops -ftree-vectorize is
enough on gcc.

Quick bench results on the worst case workload:
master no checksums: tps = 15.561848
master with checksums: tps = 1.695450
simd checksums: tps = 14.602698

Regards,
Ants Aasma
--
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt
Web: http://www.postgresql-support.de

Attachment Content-Type Size
simd-checksums.patch application/octet-stream 11.3 KB

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