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[Xen-devel] Re: Is QoS of virtual disk not necessary?

To: Andi Kleen <andi@xxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: Is QoS of virtual disk not necessary?
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 24 Aug 2007 18:40:54 +0100
Cc: Satoshi Uchida <s-uchida@xxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx
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On 24/8/07 18:26, "Andi Kleen" <andi@xxxxxxxxxxxxxx> wrote:

>> Another nice thing would be that if we do not use CFQ then we do not need a
>> kernel thread per VBD.
> 
> It would be probably easy to extend CFQ2 to use an user passed identifier
> instead of per task for sharing if that's your goal. For a kernel driver
> like blkback you could just switch around multiple current->io_contexts.

Does current->io_context get latched before submit_bh() (or whatever similar
function it is we use) returns? Is this true even in older 2.6 kernels with
old CFQ?

 -- Keir



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