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Re: [Qemu-block] [Qemu-devel] [RFC PATCH 1/9] qapi/block-core: add optio
From: |
Aarushi Mehta |
Subject: |
Re: [Qemu-block] [Qemu-devel] [RFC PATCH 1/9] qapi/block-core: add option for io_uring |
Date: |
Wed, 22 May 2019 06:21:51 +0530 |
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
> > ---
> > qapi/block-core.json | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/qapi/block-core.json b/qapi/block-core.json
> > index 7ccbfff9d0..116995810a 100644
> > --- a/qapi/block-core.json
> > +++ b/qapi/block-core.json
> > @@ -2776,11 +2776,12 @@
> > #
> > # @threads: Use qemu's thread pool
> > # @native: Use native AIO backend (only Linux and Windows)
> > +# @io_uring: Use linux io_uring
>
> Missing a '(since 4.1)' tag.
>
> > #
> > # Since: 2.9
> > ##
> > { 'enum': 'BlockdevAioOptions',
> > - 'data': [ 'threads', 'native' ] }
> > + 'data': [ 'threads', 'native','io_uring' ] }
>
> Missing space after ',' (not essential, but matching style is nice).
> Should the new element be defined conditionally, so that
> introspection
> only sees the new enum member when compiled for Linux?
>
I'm not sure what would be the benefits of that? We already check for
Linux at configure, and this would reduce readability. We aren't doing
this for native.
>
- [Qemu-block] [RFC PATCH 5/9] util/asyn: add aio interfaces for io_uring, (continued)
- [Qemu-block] [RFC PATCH 5/9] util/asyn: add aio interfaces for io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 2/9] block/block: add BDRV flag for io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 8/9] block/file-posix: extends to use with io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 7/9] blockdev: accept io_uring as option, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 6/9] block/io_uring: implements interfaces for io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 1/9] qapi/block-core: add option for io_uring, Aarushi Mehta, 2019/05/21
- Re: [Qemu-block] [Qemu-devel] [RFC PATCH 0/9] Add support for io_uring, Stefan Hajnoczi, 2019/05/22
- [Qemu-block] [RFC PATCH 0/9] Add support for io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 8/9] block/file-posix: extends to use with io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 9/9] configure: permits use of io_uring with probe, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 4/9] stubs: add aio interface stubs for io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 6/9] block/io_uring: implements interfaces for io_uring, Aarushi Mehta, 2019/05/21
- [Qemu-block] [RFC PATCH 7/9] blockdev: accept io_uring as option, Aarushi Mehta, 2019/05/21