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[Xen-devel] Xen dom0 network I/O scalability

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Subject: [Xen-devel] Xen dom0 network I/O scalability
From: Kaushik Kumar Ram <kaushik@xxxxxxxx>
Date: Wed, 27 Apr 2011 12:30:27 -0500
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Hi folks,

I have a few questions/clarifications about dom0 network I/O scalability. I would appreciate any feedback/pointers.

So the current implementation of netback does not scale beyond a single CPU core, thanks to the use of tasklets, making it a bottleneck (please correct me if I am wrong). I remember coming across some patches which attempts to use softirqs instead of tasklets to solve this issue. But the latest version of linux-2.6-xen.hg repo does not include them. Are they included in some other version of dom0 Linux? Or will they be included in future? This seems like a very important problem to solve especially as the number of VMs and number of CPU cores go up. Is there any fundamental limitation in solving this problem?

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