From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jamal Hadi Salim Subject: Re: [PATCH net-next V2] tun: introduce tx skb ring Date: Wed, 15 Jun 2016 07:52:47 -0400 Message-ID: <5761418F.2050407__8688.37454258955$1466419389$gmane$org@mojatatu.com> References: <1465979897-4445-1-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: <1465979897-4445-1-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, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, davem@davemloft.net Cc: eric.dumazet@gmail.com, brouer@redhat.com List-Id: virtualization@lists.linuxfoundation.org On 16-06-15 04:38 AM, Jason Wang wrote: > We used to queue tx packets in sk_receive_queue, this is less > efficient since it requires spinlocks to synchronize between producer > and consumer. > > This patch tries to address this by: > > - introduce a new mode which will be only enabled with IFF_TX_ARRAY > set and switch from sk_receive_queue to a fixed size of skb > array with 256 entries in this mode. > - introduce a new proto_ops peek_len which was used for peeking the > skb length. > - implement a tun version of peek_len for vhost_net to use and convert > vhost_net to use peek_len if possible. > > Pktgen test shows about 18% improvement on guest receiving pps for small > buffers: > > Before: ~1220000pps > After : ~1440000pps > So this is more exercising the skb array improvements. For tun it would be useful to see general performance numbers on user/kernel crossing (i.e tun read/write). If you have the cycles can you run such tests? cheers, jamal