From: "Michael S. Tsirkin" <m...@redhat.com>
Date: Sun, 29 Jul 2012 20:40:16 UTC
Local: Sun, Jul 29 2012 4:40 pm
Subject: Re: [net-next RFC V5 3/5] virtio: intorduce an API to set affinity for a virtqueue
On Fri, Jul 27, 2012 at 04:38:11PM +0200, Paolo Bonzini wrote:You need to run irqbalancer in guest to make it actually work. Do you?
> Il 05/07/2012 12:29, Jason Wang ha scritto:
> > Sometimes, virtio device need to configure irq affiniry hint to maximize the
> > performance. Instead of just exposing the irq of a virtqueue, this patch
> > introduce an API to set the affinity for a virtqueue.
> > The api is best-effort, the affinity hint may not be set as expected due to
> > - if device uses INTX, we just ignore the request
> > Signed-off-by: Jason Wang <jasow...@redhat.com>
> Hmm, I don't see any benefit from this patch, I need to use
> with irq_set_affinity_hint:
> with irq_set_affinity:
> I gathered these quickly after boot, but real benchmarks show the same
> I also tried adding IRQ_NO_BALANCING, but the only effect is that I
> The queue steering algorithm I use in virtio-scsi is extremely simple
> # taskset -c 0 dd if=/dev/sda bs=1M count=1000 of=/dev/null iflag=direct
> All my requests come from CPU#0 and thus go to the first virtqueue, but
> Did you set the affinity manually in your experiments, or perhaps there
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