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[Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on V
From: |
Marcelo Tosatti |
Subject: |
[Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY |
Date: |
Mon, 22 Feb 2010 11:29:20 -0300 |
User-agent: |
Mutt/1.5.20 (2009-08-17) |
On Mon, Feb 22, 2010 at 04:20:52PM +0200, Avi Kivity wrote:
> On 02/22/2010 03:59 PM, Marcelo Tosatti wrote:
> >VIRTIO_PCI_QUEUE_NOTIFY is used to inform availability of new buffers,
> >so wakeup the iothread to process that information immediately.
> >
> >Reported-by: Amit Shah<address@hidden>
> >Signed-off-by: Marcelo Tosatti<address@hidden>
> >
> >Index: qemu/hw/virtio-pci.c
> >===================================================================
> >--- qemu.orig/hw/virtio-pci.c
> >+++ qemu/hw/virtio-pci.c
> >@@ -204,6 +204,7 @@ static void virtio_ioport_write(void *op
> > break;
> > case VIRTIO_PCI_QUEUE_NOTIFY:
> > virtio_queue_notify(vdev, val);
> >+ qemu_notify_event();
> > break;
>
> virtio_queue_notify() will call ->handle_output(), which should
> either do what's needed to be done, or wake up some iothread itself.
kick is used to inform either output processing, in which case
->handle_output() does what its supposed to.
But its also used to inform availability of new buffers, which is common
to all virtio devices. So what is the point pushing this to
->handle_output?
Are you concerned about spurious wakeups?
- [Qemu-devel] [patch uq/master 0/2] wake iothread on virtio kick / flush_coalesced_mmio smp_wmb, Marcelo Tosatti, 2010/02/22
- [Qemu-devel] [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Marcelo Tosatti, 2010/02/22
- [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Avi Kivity, 2010/02/22
- [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY,
Marcelo Tosatti <=
- [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Avi Kivity, 2010/02/22
- [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Marcelo Tosatti, 2010/02/22
- [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Anthony Liguori, 2010/02/22
- [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Avi Kivity, 2010/02/22
- [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Anthony Liguori, 2010/02/22
- Re: [Qemu-devel] Re: [patch uq/master 1/2] virtio-pci: wake up iothread on VIRTIO_PCI_QUEUE_NOTIFY, Avi Kivity, 2010/02/22
[Qemu-devel] [patch uq/master 2/2] kvm-all.c: define smp_wmb and use it for coalesced mmio, Marcelo Tosatti, 2010/02/22