On Wed, Jun 06, 2012 at 04:25:55PM +0100, Stefan Hajnoczi wrote:
> On Mon, Jun 4, 2012 at 12:11 PM, Michael S. Tsirkin wrote:
> > On Fri, Jun 01, 2012 at 10:13:06AM +0100, Stefan Hajnoczi wrote:
> >> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
> >> index 774c31d..d674977 1
On Mon, Jun 4, 2012 at 12:11 PM, Michael S. Tsirkin wrote:
> On Fri, Jun 01, 2012 at 10:13:06AM +0100, Stefan Hajnoczi wrote:
>> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
>> index 774c31d..d674977 100644
>> --- a/drivers/block/virtio_blk.c
>> +++ b/drivers/block/virtio_b
On Mon, Jun 4, 2012 at 12:15 PM, Michael S. Tsirkin wrote:
> On Fri, Jun 01, 2012 at 10:13:06AM +0100, Stefan Hajnoczi wrote:
>> Other block drivers (cciss, rbd, nbd) use spin_unlock_irq() so I followed
>> that.
>> To me this seems wrong: blk_run_queue() uses spin_lock_irqsave() but we
>> enable
Stefan Hajnoczi wrote on 06/01/2012 04:13:06
AM:
>
> Holding the vblk->lock across kick causes poor scalability in SMP
> guests. If one CPU is doing virtqueue kick and another CPU touches the
> vblk->lock it will have to spin until virtqueue kick completes.
>
> This patch reduces system% CPU util
On Fri, Jun 01, 2012 at 10:13:06AM +0100, Stefan Hajnoczi wrote:
> Other block drivers (cciss, rbd, nbd) use spin_unlock_irq() so I followed
> that.
> To me this seems wrong: blk_run_queue() uses spin_lock_irqsave() but we enable
> irqs with spin_unlock_irq(). If the caller of blk_run_queue() had
On Fri, Jun 01, 2012 at 10:13:06AM +0100, Stefan Hajnoczi wrote:
> Holding the vblk->lock across kick causes poor scalability in SMP
> guests. If one CPU is doing virtqueue kick and another CPU touches the
> vblk->lock it will have to spin until virtqueue kick completes.
>
> This patch reduces sy
On 06/01/2012 05:13 PM, Stefan Hajnoczi wrote:
Holding the vblk->lock across kick causes poor scalability in SMP
guests. If one CPU is doing virtqueue kick and another CPU touches the
vblk->lock it will have to spin until virtqueue kick completes.
This patch reduces system% CPU utilization in S
Holding the vblk->lock across kick causes poor scalability in SMP
guests. If one CPU is doing virtqueue kick and another CPU touches the
vblk->lock it will have to spin until virtqueue kick completes.
This patch reduces system% CPU utilization in SMP guests that are
running multithreaded I/O-boun
