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Date: Mon, 23 May 2016 16:56:05 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 5/9] virtio-blk: multiqueue batch notify
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>, Kevin Wolf <kwolf@redhat.com>, Ming Lei <ming.lei@canonical.com>, qemu-devel@nongnu.org

On Mon, 05/23 10:17, Paolo Bonzini wrote:
> 
> 
> On 23/05/2016 04:43, Fam Zheng wrote:
> > > The batch notification BH needs to know which virtqueues to notify when
> > > multiqueue is enabled.  Use a bitmap to track the virtqueues that with
> > > pending notifications.
> > 
> > This approach works great as long as VQs are in the same iothread. An
> > alternative way would be using separate BH per VQ, which will naturely work with
> > multi queue block layer in the future.  Should we just go for that in the first
> > place?  Seems less code churn, and no imaginable disadvantage compared to this
> > patch.
> 
> It can be slower because all BHs are walked during aio_bh_poll, not just
> the scheduled ones.
> 

OK, this is a fair point. Thanks.

Fam