From: Pekka Enberg <penberg@kernel.org>
To: Anthony Liguori <aliguori@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>, Asias He <asias.hejun@gmail.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Mark McLoughlin <markmc@redhat.com>,
Cyrill Gorcunov <gorcunov@gmail.com>,
Sasha Levin <levinsasha928@gmail.com>,
Prasad Joshi <prasadjoshi124@gmail.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH 1/2] kvm tools: Respect ISR status in virtio header
Date: Sat, 07 May 2011 17:50:34 +0300 [thread overview]
Message-ID: <1304779834.10621.14.camel@jaguar> (raw)
In-Reply-To: <4DC545BA.3030501@us.ibm.com>
On Sat, 2011-05-07 at 08:14 -0500, Anthony Liguori wrote:
> It seems like this patch is simply avoiding raising the interrupt line
> if the ISR has not been acknowledged yet. I don't think there's a
> functional issue here but I'm surprised that it's a win. There should
> be a very short window when the interrupt is lowered in the APIC but
> still not acknowledged in the ISR.
>
> You should just be saving a pretty cheap system call. I wonder if the
> system call is taking longer than it should..
The patch seems to fix a bug where the guest kernel breaks down under
interrupt storm and stops doing VIRTIO_PCI_QUEUE_NOTIFY. We assumed it
was something with our code but your comments make me wonder if there's
a real problem in KVM_IRQ_LINE.
Pekka
next prev parent reply other threads:[~2011-05-07 14:50 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-07 2:34 [PATCH 1/2] kvm tools: Respect ISR status in virtio header Asias He
2011-05-07 2:34 ` [PATCH 2/2] kvm tools: Respect VRING_AVAIL_F_NO_INTERRUPT Asias He
2011-05-07 7:55 ` Ingo Molnar
2011-05-07 9:03 ` Pekka Enberg
2011-05-07 11:25 ` Asias He
2011-05-07 9:30 ` [PATCH 1/2] kvm tools: Respect ISR status in virtio header Ingo Molnar
2011-05-07 10:34 ` Sasha Levin
2011-05-07 10:39 ` Pekka Enberg
2011-05-07 10:39 ` Asias He
2011-05-07 11:15 ` Asias He
2011-05-07 14:00 ` Ingo Molnar
2011-05-07 14:24 ` Asias He
2011-05-07 13:14 ` Anthony Liguori
2011-05-07 14:02 ` Ingo Molnar
2011-05-07 14:21 ` Anthony Liguori
2011-05-07 14:47 ` Ingo Molnar
2011-05-07 14:52 ` Pekka Enberg
2011-05-07 14:55 ` Ingo Molnar
2011-05-07 14:50 ` Pekka Enberg [this message]
2011-05-07 15:01 ` Anthony Liguori
2011-05-07 15:02 ` Pekka Enberg
2011-05-07 15:06 ` Ingo Molnar
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