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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Sat, 21 May 2016 18:02:52 +0200
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Subject: Re: [Qemu-devel] [PATCH 5/9] virtio-blk: multiqueue batch notify
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To: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Ming Lei <ming.lei@canonical.com>, Fam Zheng <famz@redhat.com>



On 21/05/2016 01:40, Stefan Hajnoczi wrote:
> +    while ((i = find_next_bit(s->batch_notify_vqs, nvqs, i)) < nvqs) {
> +        VirtQueue *vq = virtio_get_queue(vdev, i);
> +
> +        bitmap_clear(s->batch_notify_vqs, i, 1);

clear_bit?

> +        if (s->dataplane_started && !s->dataplane_disabled) {
> +            virtio_blk_data_plane_notify(s->dataplane, vq);
> +        } else {
> +            virtio_notify(vdev, vq);
> +        }

The find_next_bit loop is not very efficient and could use something
similar to commit 41074f3 ("omap_intc: convert ffs(3) to ctz32() in
omap_inth_sir_update()", 2015-04-28).  But it can be improved later.

Thanks,

Paolo