From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CBCAC43334 for ; Tue, 5 Jul 2022 02:01:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233980AbiGECBy (ORCPT ); Mon, 4 Jul 2022 22:01:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229453AbiGECBy (ORCPT ); Mon, 4 Jul 2022 22:01:54 -0400 Received: from out30-44.freemail.mail.aliyun.com (out30-44.freemail.mail.aliyun.com [115.124.30.44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE34A5FA0; Mon, 4 Jul 2022 19:01:51 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R611e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=xuanzhuo@linux.alibaba.com;NM=1;PH=DS;RN=36;SR=0;TI=SMTPD_---0VIPVqL._1656986505; Received: from localhost(mailfrom:xuanzhuo@linux.alibaba.com fp:SMTPD_---0VIPVqL._1656986505) by smtp.aliyun-inc.com; Tue, 05 Jul 2022 10:01:46 +0800 Message-ID: <1656986432.1164997-2-xuanzhuo@linux.alibaba.com> Subject: Re: [PATCH v11 39/40] virtio_net: support tx queue resize Date: Tue, 5 Jul 2022 10:00:32 +0800 From: Xuan Zhuo To: Jason Wang Cc: Richard Weinberger , Anton Ivanov , Johannes Berg , "Michael S. Tsirkin" , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Hans de Goede , Mark Gross , Vadim Pasternak , Bjorn Andersson , Mathieu Poirier , Cornelia Huck , Halil Pasic , Eric Farman , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Vincent Whitchurch , linux-um@lists.infradead.org, netdev@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, bpf@vger.kernel.org, kangjie.xu@linux.alibaba.com, virtualization@lists.linux-foundation.org References: <20220629065656.54420-1-xuanzhuo@linux.alibaba.com> <20220629065656.54420-40-xuanzhuo@linux.alibaba.com> <102d3b83-1ae9-a59a-16ce-251c22b7afb0@redhat.com> In-Reply-To: <102d3b83-1ae9-a59a-16ce-251c22b7afb0@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Mon, 4 Jul 2022 11:45:52 +0800, Jason Wang wrote: > > =E5=9C=A8 2022/6/29 14:56, Xuan Zhuo =E5=86=99=E9=81=93: > > This patch implements the resize function of the tx queues. > > Based on this function, it is possible to modify the ring num of the > > queue. > > > > Signed-off-by: Xuan Zhuo > > --- > > drivers/net/virtio_net.c | 48 ++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 48 insertions(+) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index 6ab16fd193e5..fd358462f802 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -135,6 +135,9 @@ struct send_queue { > > struct virtnet_sq_stats stats; > > > > struct napi_struct napi; > > + > > + /* Record whether sq is in reset state. */ > > + bool reset; > > }; > > > > /* Internal representation of a receive virtqueue */ > > @@ -279,6 +282,7 @@ struct padded_vnet_hdr { > > }; > > > > static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *bu= f); > > +static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf= ); > > > > static bool is_xdp_frame(void *ptr) > > { > > @@ -1603,6 +1607,11 @@ static void virtnet_poll_cleantx(struct receive_= queue *rq) > > return; > > > > if (__netif_tx_trylock(txq)) { > > + if (READ_ONCE(sq->reset)) { > > + __netif_tx_unlock(txq); > > + return; > > + } > > + > > do { > > virtqueue_disable_cb(sq->vq); > > free_old_xmit_skbs(sq, true); > > @@ -1868,6 +1877,45 @@ static int virtnet_rx_resize(struct virtnet_info= *vi, > > return err; > > } > > > > +static int virtnet_tx_resize(struct virtnet_info *vi, > > + struct send_queue *sq, u32 ring_num) > > +{ > > + struct netdev_queue *txq; > > + int err, qindex; > > + > > + qindex =3D sq - vi->sq; > > + > > + virtnet_napi_tx_disable(&sq->napi); > > + > > + txq =3D netdev_get_tx_queue(vi->dev, qindex); > > + > > + /* 1. wait all ximt complete > > + * 2. fix the race of netif_stop_subqueue() vs netif_start_subqueue() > > + */ > > + __netif_tx_lock_bh(txq); > > + > > + /* Prevent rx poll from accessing sq. */ > > + WRITE_ONCE(sq->reset, true); > > > Can we simply disable RX NAPI here? Disable rx napi is indeed a simple solution. But I hope that when dealing w= ith tx, it will not affect rx. Thanks. > > Thanks > > > > + > > + /* Prevent the upper layer from trying to send packets. */ > > + netif_stop_subqueue(vi->dev, qindex); > > + > > + __netif_tx_unlock_bh(txq); > > + > > + err =3D virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf= ); > > + if (err) > > + netdev_err(vi->dev, "resize tx fail: tx queue index: %d err: %d\n", = qindex, err); > > + > > + /* Memory barrier before set reset and start subqueue. */ > > + smp_mb(); > > + > > + WRITE_ONCE(sq->reset, false); > > + netif_tx_wake_queue(txq); > > + > > + virtnet_napi_tx_enable(vi, sq->vq, &sq->napi); > > + return err; > > +} > > + > > /* > > * Send command via the control virtqueue and check status. Commands > > * supported by the hypervisor, as indicated by feature bits, should >