| From: | Greg Smith <greg(at)2ndQuadrant(dot)com> |
|---|---|
| To: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: how to demonstrate the effect of direct I/O ? |
| Date: | 2012-02-08 03:13:24 |
| Message-ID: | 4F31E854.7080208@2ndQuadrant.com |
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| Lists: | pgsql-performance |
On 02/04/2012 06:25 PM, Tomas Vondra wrote:
> What should I do to see the effect of direct I/O?
Test something other than a mainstream Linux filesystem. The two times
I've either measured an improvement myself for direct I/O were a)
Veritas VxFS on Linux, which has some documented acceleration here and
b) on Solaris. You won't find a compelling performance improvement
listed at
https://ext4.wiki.kernel.org/articles/c/l/a/Clarifying_Direct_IO%27s_Semantics_fd79.html
and Linux has generally ignored direct I/O as something important to
optimize for.
--
Greg Smith 2ndQuadrant US greg(at)2ndQuadrant(dot)com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
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