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Re: Linux I/O tuning: CFQ vs. deadline

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: pgsql-performance(at)postgresql(dot)org, Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at>
Subject: Re: Linux I/O tuning: CFQ vs. deadline
Date: 2010-02-08 15:30:13
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
Kevin Grittner wrote:
> I'll keep this in mind as something to try if we have problem
> performance in line with what that page describes, though....

That's basically what I've been trying to make clear all along:  people 
should keep an open mind, watch what happens, and not make any 
assumptions.  There's no clear cut preference for one scheduler or the 
other in all situations.  I've seen CFQ do much better, you and Albe 
report situations where the opposite is true.  I was just happy to see 
another report of someone running into the same sort of issue I've been 
seeing, because I didn't have very much data to offer about why the 
standard advice of "always use deadline for a database app" might not 
apply to everyone.

Greg Smith    2ndQuadrant   Baltimore, MD
PostgreSQL Training, Services and Support

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Subject: Re: Linux I/O tuning: CFQ vs. deadline
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