Re: [Qemu-block] [Qemu-devel] [RFC PATCH 1/9] qapi/block-core: add option for io_uring

[Stefan Hajnoczi]

On Wed, May 22, 2019 at 06:21:51AM +0530, Aarushi Mehta wrote:
> On Tue, 2019-05-21 at 19:39 -0500, Eric Blake wrote:
> > On 5/21/19 6:52 PM, Aarushi Mehta wrote:
> > > Signed-off-by: Aarushi Mehta <address@hidden>
> > 
> > Sparse on the details. The subject line says what, but without a
> > 'why'
> > for how io_uring is different from existing aio options, it's hard to
> > see why I'd want to use it. Do you have any benchmark numbers?
> 
> For peak performance, io_uring helps us get to 1.7M 4k IOPS with
> polling. aio reaches a performance cliff much lower than that, at 608K.
> If we disable polling, io_uring is able to drive about 1.2M IOPS for
> the (otherwise) same test case.
> 
> More details, and the source for the above is at
> http://kernel.dk/io_uring.pdf

So that Aarushi's email isn't accidentally misquoted later on:

These numbers are not via QEMU.  QEMU is likely to show different
performance results and they are expected to be lower due to
virtualization overhead.

Stefan

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