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Re: [Xen-users] Asynchronous IO

To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-users] Asynchronous IO
From: Priya PM <pmpriya@xxxxxxxxx>
Date: Thu, 8 Sep 2005 17:16:37 -0600
Cc: ian.pratt@xxxxxxxxxxxx, Xen-users@xxxxxxxxxxxxxxxxxxx
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Hi,
 
I tried the same operation with unstable version too. I have changed the IO scheduler to atropos and tried. But no use. I always get the same results. Has anyone checked the Asynchronous IO path using libaio?
 
It would be very much helpful if you can give me some ideas to proceed further,
 
Thanks,
Priya.

 
On 9/8/05, Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx> wrote:
> I have installed Xen on Linux 2.6.11.10 and i am trying to do
> Asynchronous Direct IO on SAS drives. The application which
> does the asynchronous direct io on SAS drive is running on
> Domain 0. Actually the IOPs what i get for a 512Bytes IO size
> is 67, but if i do the same operation on Linux 2.6.11.10
> native kernel, i get 267 IOPs.Can anyone tell me why this
> huge differnece? Am i missing something? In the current setup
> on Xen, if i do Synchronous IO, then i am getting 265 IOPs
> which is expected. So i am wondering why Asynchronous IO
> should behave this way? Is there any reason??

That's odd. You might want to try the -unstable tree. I know Andy has
used AIO just fine on -unstable.

Ian

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