From: Sheng Yang <sheng@linux.intel.com>
To: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org
Subject: Re: [PATCH 0/3] Emulate MSI-X mask bits for assigned devices
Date: Mon, 11 Oct 2010 17:34:24 +0800 [thread overview]
Message-ID: <201010111734.24896.sheng@linux.intel.com> (raw)
In-Reply-To: <20100930164451.GC29881@amt.cnet>
On Friday 01 October 2010 00:44:51 Marcelo Tosatti wrote:
> On Tue, Sep 28, 2010 at 05:44:09PM +0800, Sheng Yang wrote:
> > Hi Avi & Marcelo
> >
> > This patchset would add emulation of MSI-X mask bit for assigned devices
> > in QEmu.
> >
> > BTW: We are also purposed an acceleration of MSI-X mask bit for KVM - to
> > get it done in kernel. That's because sometime MSI-X mask bit was
> > accessed very frequently by guest and emulation in QEmu cost a lot(tens
> > to hundreds percent CPU utilization sometime), e.g. guest using Linux
> > 2.6.18 or under some heavy workload. The method has been proved
> > efficient in Xen, but it would require VMM to handle MSI-X table. Is
> > that OK with you?
>
> It would be good to understand where that cost is, before. Eg. do you
> commit kvm irq route frequently when guest unmasks?
I don't think it would cause performance issue, but maybe need another bulk of
codes in kernel. I would post the in-kernel patch later, which is easier for
discuss. :)
--
regards
Yang, Sheng
prev parent reply other threads:[~2010-10-11 9:34 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-28 9:44 [PATCH 0/3] Emulate MSI-X mask bits for assigned devices Sheng Yang
2010-09-28 9:44 ` [PATCH 1/3] KVM: Emulation " Sheng Yang
2010-09-28 13:36 ` Michael S. Tsirkin
2010-09-29 1:17 ` Sheng Yang
2010-09-30 16:25 ` Marcelo Tosatti
2010-09-29 8:36 ` Avi Kivity
2010-09-30 5:41 ` Sheng Yang
2010-10-03 13:03 ` Avi Kivity
2010-10-11 9:32 ` Sheng Yang
2010-09-30 16:18 ` Marcelo Tosatti
2010-10-11 9:49 ` Sheng Yang
2010-10-11 17:11 ` Marcelo Tosatti
2010-10-03 11:12 ` Michael S. Tsirkin
2010-10-11 9:28 ` Sheng Yang
2010-10-11 10:01 ` Michael S. Tsirkin
2010-10-12 6:49 ` Sheng Yang
2010-10-12 18:28 ` Michael S. Tsirkin
2010-10-13 1:03 ` Sheng Yang
2010-10-13 10:35 ` Michael S. Tsirkin
2010-10-12 18:30 ` Michael S. Tsirkin
2010-10-13 0:58 ` Sheng Yang
2010-10-13 12:03 ` Michael S. Tsirkin
2010-09-28 9:44 ` [PATCH 2/3] qemu-kvm: device assignment: Some clean up for MSI-X code Sheng Yang
2010-09-28 9:44 ` [PATCH 3/3] qemu-kvm: device assignment: emulate MSI-X mask bits Sheng Yang
2010-09-30 16:44 ` [PATCH 0/3] Emulate MSI-X mask bits for assigned devices Marcelo Tosatti
2010-10-11 9:34 ` Sheng Yang [this message]
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