Re: how to demonstrate the effect of direct I/O ?

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.

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Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
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