Re: [Qemu-devel] [RFC PATCH 2/3] raw-posix: Convert Linux AIO submission to coroutines

[Ming Lei]

On 11/28/14, Markus Armbruster <address@hidden> wrote:
> Ming Lei <address@hidden> writes:
>
>> Hi Kevin,
>>
>> On Wed, Nov 26, 2014 at 10:46 PM, Kevin Wolf <address@hidden> wrote:
>>> This improves the performance of requests because an ACB doesn't need to
>>> be allocated on the heap any more. It also makes the code nicer and
>>> smaller.
>>
>> I am not sure it is good way for linux aio optimization:
>>
>> - for raw image with some constraint, coroutine can be avoided since
>> io_submit() won't sleep most of times
>>
>> - handling one time coroutine takes much time than handling malloc,
>> memset and free on small buffer, following the test data:
>>
>>          --   241ns per coroutine
>
> What do you mean by "coroutine" here?  Create + destroy?  Yield?

Please see perf_cost() in tests/test-coroutine.c

Thanks,
Ming Lei