Re: [patch 0/4] use smp_send_reschedule in vcpu_kick / assigned dev host intx race fix

[Sheng Yang <sheng@linux.intel.com>]

On Thursday 30 April 2009 09:59:56 Sheng Yang wrote:
> On Thursday 30 April 2009 08:56:57 Sheng Yang wrote:
> > On Thursday 30 April 2009 01:47:57 Marcelo Tosatti wrote:
> > > On Tue, Apr 28, 2009 at 03:08:46PM +0800, Sheng Yang wrote:
> > > > Ack all. This also solved one bug by my hand. Thanks!
> > > >
> > > > I observe one point: the performance of high workload interrupt(e.g.
> > > > 10 gigabyte oplin card) dropped dramatically with
> > > > smp_send_reschedule() method... In one environment(the speed of oplin
> > > > card also limited by cpu performance), Using
> > > > smp_call_function_single() can get more than 1G bit/s stably(native
> > > > got 1.2G), but smp_send_reschedule() can only got around 600M
> > > > bit/s... And the rescheduling interrupt number is about 2000/second
> > > > per cpu. And the interrupt rate is about tens of thousands per second
> > > > for the device.
> > > >
> > > > Anyway, this method is more elegant and correct. Though there is
> > > > still room for optimize - but of course, the correctness is first
> > > > priority.
> > >
> > > Are you using the compat code or a kvm.git kernel? Can you remove only
> > > the last patch (the spinlock) to confirm its the cause of the slowdown?
> >
> > I am using kvm.git.
> >
> > I said this because I tried the old version of patch(which have warning)
> > and it would got more than 1G/sec.
> >
> > I'd like to take a close look at what's happened.
>
> Still ACK this patchset.
>
> And sorry, my memory messed...
>
> The old version of patch and this one offered the same performance. So the
> problem is not here.
>
> I get more than 1g per second by one of myself's experiment.
>
> Disable/enable irq purposed to use with level interrupt to prevent it send
> interrupt again after kernel handler return, but it not applied to
> MSI/MSI-X. Though some interrupt may be merged with one, but AFAIK the
> driver can handle it well.
>
> My experiment is discard disable/enable IRQ for MSI/MSI-X, then can get
> much better performance for oplin card, 2x with disable/enable one.
>
> I would prepare a patch for it.

Hi Avi

Is there any issue blocked this patchset?

Thanks!

-- 
regards
Yang, Sheng