From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Fastabend Subject: Re: [PATCH net 9/9] virtio-net: XDP support for small buffers Date: Mon, 2 Jan 2017 14:43:39 -0800 Message-ID: <586AD79B.2070203@gmail.com> References: <1482503852-12438-1-git-send-email-jasowang@redhat.com> <1482503852-12438-10-git-send-email-jasowang@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1482503852-12438-10-git-send-email-jasowang@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jason Wang , mst@redhat.com, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: john.r.fastabend@intel.com List-Id: virtualization@lists.linuxfoundation.org On 16-12-23 06:37 AM, Jason Wang wrote: > Commit f600b6905015 ("virtio_net: Add XDP support") leaves the case of > small receive buffer untouched. This will confuse the user who want to > set XDP but use small buffers. Other than forbid XDP in small buffer > mode, let's make it work. XDP then can only work at skb->data since > virtio-net create skbs during refill, this is sub optimal which could > be optimized in the future. > > Cc: John Fastabend > Signed-off-by: Jason Wang > --- > drivers/net/virtio_net.c | 112 ++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 87 insertions(+), 25 deletions(-) > Hi Jason, I was doing some more testing on this what do you think about doing this so that free_unused_bufs() handles the buffer free with dev_kfree_skb() instead of put_page in small receive mode. Seems more correct to me. diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 783e842..27ff76c 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1898,6 +1898,10 @@ static void free_receive_page_frags(struct virtnet_info *vi) static bool is_xdp_queue(struct virtnet_info *vi, int q) { + /* For small receive mode always use kfree_skb variants */ + if (!vi->mergeable_rx_bufs) + return false; + if (q < (vi->curr_queue_pairs - vi->xdp_queue_pairs)) return false; else if (q < vi->curr_queue_pairs) patch is untested just spotted doing code review. Thanks, John