Messages in this thread Patch in this message | | | Date | Mon, 29 Oct 2012 17:49:51 +0200 | From | "Michael S. Tsirkin" <> | Subject | [PATCH net-next 8/8] vhost-net: reduce vq polling on tx zerocopy |
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It seems that to avoid deadlocks it is enough to poll vq before we are going to use the last buffer. This should be faster than c70aa540c7a9f67add11ad3161096fb95233aa2e.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- drivers/vhost/net.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 8e9de79..3967f82 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -197,8 +197,16 @@ static void vhost_zerocopy_callback(struct ubuf_info *ubuf, int status) { struct vhost_ubuf_ref *ubufs = ubuf->ctx; struct vhost_virtqueue *vq = ubufs->vq; - - vhost_poll_queue(&vq->poll); + int cnt = atomic_read(&ubufs->kref.refcount); + + /* + * Trigger polling thread if guest stopped submitting new buffers: + * in this case, the refcount after decrement will eventually reach 1 + * so here it is 2. + * We also trigger polling periodically after each 16 packets. + */ + if (cnt <= 2 || !(cnt % 16)) + vhost_poll_queue(&vq->poll); /* set len to mark this desc buffers done DMA */ vq->heads[ubuf->desc].len = status ? VHOST_DMA_FAILED_LEN : VHOST_DMA_DONE_LEN; -- MST
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