Re: [Qemu-devel] [PATCH 01/15] qemu coroutine: support bypass mode

[Ming Lei]

On Fri, Aug 1, 2014 at 9:48 PM, Ming Lei <address@hidden> wrote:
> On Fri, Aug 1, 2014 at 9:13 PM, Stefan Hajnoczi <address@hidden> wrote:
>> On Fri, Aug 01, 2014 at 10:54:02AM +0800, Ming Lei wrote:
>>> On Fri, Aug 1, 2014 at 12:30 AM, Paolo Bonzini <address@hidden> wrote:
>>> > Il 31/07/2014 18:13, Ming Lei ha scritto:
>>> >> Follows 'perf report' result on cycles event for with/without bypass
>>> >> coroutine:
>>> >>
>>> >>     http://pastebin.com/ae0vnQ6V
>>> >>
>>> >> From the profiling result, looks bdrv_co_do_preadv() is a bit slow
>>> >> without bypass coroutine.
>>> >
>>> > Yeah, I can count at least 3.3% time spent here:
>>> >
>>> > 0.87%          bdrv_co_do_preadv
>>> > 0.79%          bdrv_aligned_preadv
>>> > 0.71%          qemu_coroutine_switch
>>> > 0.52%          tracked_request_begin
>>> > 0.45%          coroutine_swap
>>> >
>>> > Another ~3% wasted in malloc, etc.
>>>
>>> That should be related with coroutine and the BH in bdrv_co_do_rw().
>>> In this post I didn't apply Stephan's coroutine resize patch which might
>>> decrease usage of malloc() for coroutine.
>>
>> Please rerun with "[PATCH v3 0/2] coroutine: dynamically scale pool
>> size".
>
> No problem, will do that. Actually in my last post with rfc, this patchset
> was against your coroutine resize patches.
>
> I will provide the profile data tomorrow.

Please see below link for without bypass coroutine, and with
your coroutine resize patches(V3):

   http://pastebin.com/10y00sir

BTW, if anyone likes to play this stuff, these patches can be
pulled from below tree easily:

git://kernel.ubuntu.com/ming/qemu.git

branch:
         - v2.1.0-mq-co-resize:
              these 15 patches against 2.1.0-rc5 plus Stefan's coroutine
              resize patches(V3)
         - v2.1.0-mq:
              only these 15 patches against 2.1.0-rc5

Thanks,