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[Xen-users] tap:aio / blktap slowness

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] tap:aio / blktap slowness
From: "Ray Barnes" <rrb@xxxxxxxxxxxx>
Date: Fri, 9 Nov 2007 10:45:36 -0500
Delivery-date: Mon, 19 Nov 2007 09:55:53 -0800
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Can anyone explain to me why tap:aio sucks so badly?
 
We've got numerous CentOS 5 dom0s running file-backed domUs with tap:aio.  The moment any one of them starts doing something disk-intensive, idle CPU in dom0 decreases, iowait increases, and disk IO for every other domU on the system suffers.  Where lies the problem, and what to do about it?
 
Sincerely,
 
Ray Barnes
 
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