kern/114438: [amr] Anomalous performance with multiple arrays and amr(4)

[Thomas Hurst]

The following reply was made to PR kern/114438; it has been noted by GNATS.

From: Thomas Hurst <tom at hur.st>
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/114438: [amr] Anomalous performance with multiple arrays
	and amr(4)
Date: Wed, 16 Jan 2008 18:33:55 +0000

 Further investigation would seem to implicate atime updates; every time
 reads from one array freeze, the other array has an IO queue depth (as
 reported by gstat) of ~1000 and is performing a bunch of writes.
 
 Ignoring the meta-issue of all those atime updates, it would seem the
 large work queue to one array on the card starves out other arrays.
 
 My recent tests for this have been on 7.0-RC1 as of today.
 
 -- 
 Thomas 'Freaky' Hurst
     http://hur.st/