From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>, kvm <kvm@vger.kernel.org>
Subject: Re: [RFC][PATCH] KVM: Introduce direct MSI message injection for in-kernel irqchips
Date: Mon, 24 Oct 2011 19:05:08 +0200 [thread overview]
Message-ID: <20111024170508.GB30385@redhat.com> (raw)
In-Reply-To: <4EA58DF4.2050100@siemens.com>
On Mon, Oct 24, 2011 at 06:10:28PM +0200, Jan Kiszka wrote:
> On 2011-10-24 18:05, Michael S. Tsirkin wrote:
> >> This is what I have in mind:
> >> - devices set PBA bit if MSI message cannot be sent due to mask (*)
> >> - core checks&clears PBA bit on unmask, injects message if bit was set
> >> - devices clear PBA bit if message reason is resolved before unmask (*)
> >
> > OK, but practically, when exactly does the device clear PBA?
>
> Consider a network adapter that signals messages in a RX ring: If the
> corresponding vector is masked while the guest empties the ring, I
> strongly assume that the device is supposed to take back the pending bit
> in that case so that there is no interrupt inject on a later vector
> unmask operation.
>
> Jan
Do you mean virtio here? Do you expect this optimization to give
a significant performance gain?
> --
> Siemens AG, Corporate Technology, CT T DE IT 1
> Corporate Competence Center Embedded Linux
next prev parent reply other threads:[~2011-10-24 17:04 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-21 9:19 [RFC][PATCH] KVM: Introduce direct MSI message injection for in-kernel irqchips Jan Kiszka
2011-10-21 9:42 ` Sasha Levin
2011-10-21 11:06 ` Michael S. Tsirkin
2011-10-21 11:51 ` Jan Kiszka
2011-10-21 12:04 ` Michael S. Tsirkin
2011-10-21 13:00 ` Jan Kiszka
2011-10-24 9:45 ` Avi Kivity
2011-10-24 10:19 ` Jan Kiszka
2011-10-24 11:09 ` Avi Kivity
2011-10-24 12:06 ` Jan Kiszka
2011-10-24 12:43 ` Michael S. Tsirkin
2011-10-24 13:11 ` Jan Kiszka
2011-10-24 13:43 ` Jan Kiszka
2011-10-24 14:40 ` Michael S. Tsirkin
2011-10-24 15:00 ` Jan Kiszka
2011-10-24 16:05 ` Michael S. Tsirkin
2011-10-24 16:10 ` Jan Kiszka
2011-10-24 17:05 ` Michael S. Tsirkin [this message]
2011-10-24 17:23 ` Michael S. Tsirkin
2011-10-25 7:24 ` Jan Kiszka
2011-10-25 11:20 ` Michael S. Tsirkin
2011-10-25 11:41 ` Jan Kiszka
2011-10-25 12:05 ` Michael S. Tsirkin
2011-10-25 12:21 ` Jan Kiszka
2011-10-25 13:29 ` Michael S. Tsirkin
2011-10-24 14:25 ` Michael S. Tsirkin
2011-10-25 7:56 ` Avi Kivity
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