Re: Performance test result between per-vhost kthread disable and enable

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Dec 09, 2010 at 03:31:08PM +0200, Michael S. Tsirkin wrote:
> On Tue, Nov 23, 2010 at 10:13:43AM +0800, lidong chen wrote:
> > I test the performance between per-vhost kthread disable and enable.
> > 
> > Test method:
> > Send the same traffic load between per-vhost kthread disable and
> > enable, and compare the cpu rate of host os.
> > I run five vm on kvm, each of them have five nic.
> > the vhost version which per-vhost kthread disable we used is rhel6
> > beta 2(2.6.32.60).
> > the vhost version which per-vhost kthread enable we used is rhel6 (2.6.32-71).
> > 
> > Test result:
> > with per-vhost kthread disable, the cpu rate of host os is 110%.
> > with per-vhost kthread enable, the cpu rate of host os is 130%.
> 
> Does it help if we schedule out the thread once we've passed
> once over all vqs?

Also, could you please check whether applying
kvm: fast-path msi injection with irqfd
makes any difference?

That relieves the pressure on the scheduler by
sending the interrupt directly from vhost without
involving yet another thread.