Am 22.05.2019 um 02:51 hat Aarushi Mehta geschrieben: > 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 <mehta.aar...@gmail.com> > > > > 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.
BlockdevAioOptions is used in BlockdevOptionsFile, which contains the options for two different drivers: file-posix and file-win32. Both of them support both 'threads' and 'native'. However, I don't think you'll add the new mode to the Windows driver. So I think making it conditional on CONFIG_POSIX at least is necessary. Kevin
