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From: Gleb Natapov <gleb@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Avi Kivity <avi@redhat.com>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] kvm: enable irq injection from interrupt context
Date: Thu, 16 Sep 2010 11:25:53 +0200	[thread overview]
Message-ID: <20100916092553.GV3008@redhat.com> (raw)
In-Reply-To: <20100916091054.GA20864@redhat.com>

On Thu, Sep 16, 2010 at 11:10:55AM +0200, Michael S. Tsirkin wrote:
> On Thu, Sep 16, 2010 at 11:02:56AM +0200, Gleb Natapov wrote:
> > On Wed, Sep 15, 2010 at 08:54:17PM +0200, Michael S. Tsirkin wrote:
> > > To avoid bouncing irqfd injection out to workqueue context,
> > > we must support injecting irqs from local interrupt
> > > context. Doing this seems to only require disabling
> > > irqs locally.
> > > 
> > > RFC, completely untested, x86 only.
> > > 
> > > Thoughts?
> > > 
> > We do not want to disable irqs for a long time and some of code paths
> > under lock involve looping over all cpus. For MSI injection path is
> > lockless and this is the only case that matters,
> 
> MSI only appeared in rhel6, older guests still use level interrupts.
So they are already slow for other reasons.

> Which paths require looping over all cpus? Do PCI interrupts
> need this?
> 
All interrupts need it. IOAPIC has a loop to find dst cpu for interrupt.
Pic has a loop to find cpu in virtual wire mode.

--
			Gleb.

  reply	other threads:[~2010-09-16  9:25 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-15 18:54 [PATCH RFC] kvm: enable irq injection from interrupt context Michael S. Tsirkin
2010-09-16  9:02 ` Gleb Natapov
2010-09-16  9:10   ` Michael S. Tsirkin
2010-09-16  9:25     ` Gleb Natapov [this message]
2010-09-16  9:43       ` Michael S. Tsirkin
2010-09-16  9:46       ` Avi Kivity
2010-09-16  9:53         ` Michael S. Tsirkin
2010-09-16 10:13           ` Gleb Natapov
2010-09-16 10:13             ` Michael S. Tsirkin
2010-09-16 10:20               ` Gleb Natapov
2010-09-16 10:44                 ` Michael S. Tsirkin
2010-09-16 10:54                   ` Gleb Natapov
2010-09-16 10:53                     ` Michael S. Tsirkin
2010-09-16 11:17                       ` Gleb Natapov
2010-09-16 12:13                         ` Michael S. Tsirkin
2010-09-16 12:33                           ` Gleb Natapov
2010-09-16 12:57                             ` Michael S. Tsirkin
2010-09-16 13:14                               ` Avi Kivity
2010-09-16 13:38                                 ` Michael S. Tsirkin
2010-09-16 13:50                                   ` Avi Kivity
2010-09-16 13:55                                   ` Gleb Natapov
2010-09-16 13:18                               ` Gleb Natapov
2010-09-16 13:51                                 ` Michael S. Tsirkin
2010-09-16 14:06                                   ` Gleb Natapov
2010-09-16 14:23                                     ` Michael S. Tsirkin
2010-09-16 14:51                                       ` Gleb Natapov
2010-09-16 15:24                                         ` Michael S. Tsirkin
2010-09-16 15:43                                           ` Gleb Natapov
2010-09-16 22:07                                             ` Michael S. Tsirkin
2010-09-17  7:59                                               ` Gleb Natapov
2010-09-19 10:45                                                 ` Michael S. Tsirkin
2010-09-19 10:56                                                   ` Avi Kivity
2010-09-19 10:55                                                     ` Michael S. Tsirkin
2010-09-19 11:05                                                       ` Avi Kivity
2010-09-19 11:23                                                         ` Michael S. Tsirkin
2010-09-19 11:18                                                       ` Gleb Natapov
2010-09-19 11:21                                                         ` Michael S. Tsirkin

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