Re: [PATCH] vhost: Add polling mode

Razya Ladelsky
2014-08-12T10:57:05Z

"Michael S. Tsirkin" <mst@redhat.com> wrote on 12/08/2014 12:18:50 PM:

> From: "Michael S. Tsirkin" <mst@redhat.com>
> To: David Miller <davem@davemloft.net>
> Cc: Razya Ladelsky/Haifa/IBM@IBMIL, kvm@vger.kernel.org, Alex
> Glikson/Haifa/IBM@IBMIL, Eran Raichstein/Haifa/IBM@IBMIL, Yossi
> Kuperman1/Haifa/IBM@IBMIL, Joel Nider/Haifa/IBM@IBMIL,
> abel.gordon@gmail.com, linux-kernel@vger.kernel.org,
> netdev@vger.kernel.org, virtualization@lists.linux-foundation.org
> Date: 12/08/2014 12:18 PM
> Subject: Re: [PATCH] vhost: Add polling mode
>
> On Mon, Aug 11, 2014 at 12:46:21PM -0700, David Miller wrote:
> > From: "Michael S. Tsirkin" <mst@redhat.com>
> > Date: Sun, 10 Aug 2014 21:45:59 +0200
> >
> > > On Sun, Aug 10, 2014 at 11:30:35AM +0300, Razya Ladelsky wrote:
> > ...
> > > And, did your tests actually produce 100% load on both host CPUs?
> > ...
> >
> > Michael, please do not quote an entire patch just to ask a one line
> > question.
> >
> > I truly, truly, wish it was simpler in modern email clients to delete
> > the unrelated quoted material because I bet when people do this they
> > are simply being lazy.
> >
> > Thank you.
>
> Lazy - mea culpa, though I'm using mutt so it isn't even hard.
>
> The question still stands: the test results are only valid
> if CPU was at 100% in all configurations.
> This is the reason I generally prefer it when people report
> throughput divided by CPU (power would be good too but it still
> isn't easy for people to get that number).
>

Hi Michael,

Sorry for the delay, had some problems with my mailbox, and I realized
just now that
my reply wasn't sent.
The vm indeed ALWAYS utilized 100% cpu, whether polling was enabled or
not.
The vhost thread utilized less than 100% (of the other cpu) when polling
was disabled.
Enabling polling increased its utilization to 100% (in which case both
cpus were 100% utilized).

> --
> MST
>