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 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.

-- 
regards
Yang, Sheng