From: Alex Williamson <alex.williamson@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
gleb@redhat.com, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v10 2/2] kvm: Add resampling irqfds for level triggered interrupts
Date: Wed, 19 Sep 2012 07:54:32 -0600 [thread overview]
Message-ID: <1348062872.28860.24.camel@bling.home> (raw)
In-Reply-To: <50598C1D.4050206@redhat.com>
On Wed, 2012-09-19 at 12:10 +0300, Avi Kivity wrote:
> On 09/19/2012 12:08 PM, Michael S. Tsirkin wrote:
>
> >> Whoa. Can't we put the resampler entry somewhere we don't need to
> >> search for it? Like a kvm_kernel_irq_routing_entry, that's indexed by
> >> gsi already (kvm_irq_routing_table::rt_entries[gsi]).
> >
> > I'm not sure why would we bother optimizing this,
>
> Not optimizing, simplifying.
>
> > but if we do, I guess we could look for the irq notifier
> > which is already indexed by gsi.
>
> It's not, it's looked up in a list.
I'm not sure it's a simplification because to index by gsi we suddenly
need to care how many gsis there are. I believe that currently means we
have to assume an ioapic. Creating a dumb list is a little bit of
overhead, but we get to stay blissfully unaware of the gsi
implementation. Practically we're looking at a list of 4 entries, maybe
a few times that when we expose more PCI root bridges to the guest.
Thanks,
Alex
next prev parent reply other threads:[~2012-09-19 13:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-18 3:16 [PATCH v10 0/2] kvm: level irqfd support Alex Williamson
2012-09-18 3:16 ` [PATCH v10 1/2] kvm: Provide pre-locked setup to irq ack notifier Alex Williamson
2012-09-18 3:16 ` [PATCH v10 2/2] kvm: Add resampling irqfds for level triggered interrupts Alex Williamson
2012-09-18 23:29 ` Michael S. Tsirkin
2012-09-19 8:59 ` Avi Kivity
2012-09-19 9:08 ` Michael S. Tsirkin
2012-09-19 9:10 ` Avi Kivity
2012-09-19 13:54 ` Alex Williamson [this message]
2012-09-19 14:35 ` Avi Kivity
2012-09-19 18:23 ` Alex Williamson
2012-09-19 18:48 ` Michael S. Tsirkin
2012-09-19 19:23 ` Alex Williamson
2012-09-19 19:59 ` Michael S. Tsirkin
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