Re: [PATCH 1/3] block: add queue flag for paravirt frontend drivers

Jeremy Fitzhardinge
2008-11-04T23:23:54Z

Jens Axboe wrote:
> On Mon, Oct 27 2008, Fernando Luis Vázquez Cao wrote:
>
>> As is the case with SSD devices, we do not want to idle in AS/CFQ when
>> the block device is a paravirt front-end driver. This patch adds a flag
>> (QUEUE_FLAG_VIRT) which should be used by front-end drivers such as
>> virtio_blk and xen-blkfront to indicate a paravirtualized device.
>>
>
> All three patches look fine, although we could just reuse
> QUEUE_FLAG_NONROT directly. But I agree it makes sense to make the
> distinction, so I've just applied 1-3.
>

I guess in theory you could imagine that the virtual device is mapped
directly onto a physical device, and the host OS does no scheduling, in
which case it would be appropriate for the guest do the work. But I
think otherwise this makes sense.

J