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Re: [Xen-devel] qemu-xen qdisk performance

2012/2/13 Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>:
> On Mon, 13 Feb 2012, Roger Pau Monnà wrote:
>> > Yes, great improvements.
>> > The old qemu-xen uses threads to simulate async IO so it is very slow;
>> > upstream QEMU uses Linux AIO and is much faster.
>> That's great news, so qdisk performance in qemu-upstream should be
>> similar to blktap?
> Slightly better actually, from my very quick and dirty tests.

I'm sure blktap had some context switches (from kernel to userspace)
that qdisk doesn't have, since it's a pure userland implementation, so
it's plausible for it to be faster.

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