Re: [PATCH net-next V2 1/3] vhost: better detection of available buffers
From: Stefan Hajnoczi
Date: Tue Jan 03 2017 - 08:10:37 EST
On Wed, Dec 28, 2016 at 04:09:29PM +0800, Jason Wang wrote:
> This patch tries to do several tweaks on vhost_vq_avail_empty() for a
> better performance:
>
> - check cached avail index first which could avoid userspace memory access.
> - using unlikely() for the failure of userspace access
> - check vq->last_avail_idx instead of cached avail index as the last
> step.
>
> This patch is need for batching supports which needs to peek whether
> or not there's still available buffers in the ring.
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/vhost/vhost.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>
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