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

[Stefan Hajnoczi]

On Fri, Aug 01, 2014 at 10:52:55PM +0800, Ming Lei wrote:
> 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

Thanks for sharing!

Do you have the results (IOPS and perf report) for just the coroutine
bypass (but not the other changes in this patch series)?

Coroutine: 101k IOPS
Bypass: ? IOPS

Stefan

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