Re: [Qemu-devel] [PATCH 0/2] coroutine: dynamically scale pool size

[Stefan Hajnoczi <stefanha@gmail.com>]

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On Fri, Jul 04, 2014 at 01:10:39PM +0800, Ming Lei wrote:
> On Thu, Jul 3, 2014 at 9:51 PM, Stefan Hajnoczi <stefanha@redhat.com> wrote:
> > The coroutine pool reuses exited coroutines to make qemu_coroutine_create()
> > cheap.  The size of the pool is capped to prevent it from hogging memory after
> > a period of high coroutine activity.  Previously the max size was hardcoded to
> > 64 but this doesn't scale with guest size.
> >
> > A guest with lots of disks can do more parallel I/O and therefore requires a
> > larger coroutine pool size.  This series tries to solve the problem by scaling
> > pool size according to the number of drives.
> >
> > Ming: Please let me know if this eliminates the rt_sigprocmask system calls you
> > are seeing.  It should solve part of the performance regression you have seen
> > in qemu.git/master virtio-blk dataplane.
> 
> With both the two coroutine patches and the block plug&unplug patches,
> performance of qemu.git/master virtio-blk dataplane can recover to level of
> QEMU 2.0.

/me does the happy dance

Thanks for your great efforts in investigating and fixing the
regression!

Stefan

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