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[Xen-devel] Disk IO scheduling in XEN

To: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Disk IO scheduling in XEN
From: Paresh Nakhe <paresh.nakhe@xxxxxxxxx>
Date: Fri, 25 Mar 2011 01:49:31 +0530
Delivery-date: Thu, 24 Mar 2011 13:20:27 -0700
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Hi,

We are working on a project to modify the disk scheduling mechanism in XEN a bit in an attempt to improve it. In the paper "Xen and the Art of Virtualization"  following is mentioned.

"Xen services batches of requests from competing domains in a
simple round-robin fashion; these are then passed to a standard elevator
scheduler before reaching the disk hardware
"

We were going through linux-jeremy source code in an attempt to map the above in code. We could not however do so. On the contrary we came to the conclusion that there is no such mechanism. Domain 0 services requests as soon as it receives a hypercall from a guest domain. Are we right?

Which one would be better first come first serve or round robin and why?

Thanks
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