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@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com
