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([2001:ee0:4f0f:b1d0:7a59:6e8f:1a0b:107a]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3593dcc9c37sm6888309a91.8.2026.02.27.22.25.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Feb 2026 22:25:20 -0800 (PST) Message-ID: <829f4263-dfd2-4664-b66c-0a65f35aa57a@gmail.com> Date: Sat, 28 Feb 2026 13:25:13 +0700 Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next] virtio-net: xsk: Support wakeup on RX side To: Jason Xing Cc: netdev@vger.kernel.org, "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260227150949.13089-1-minhquangbui99@gmail.com> <43b3b8dc-bc99-497a-a845-a9697c126d3f@gmail.com> Content-Language: en-US From: Bui Quang Minh In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 2/28/26 13:16, Jason Xing wrote: > On Sat, Feb 28, 2026 at 1:03 PM Bui Quang Minh wrote: >> Hi Jason, >> >> On 2/28/26 10:49, Jason Xing wrote: >>> Hi Bui, >>> >>> On Fri, Feb 27, 2026 at 11:20 PM Bui Quang Minh >>> wrote: >>>> When XDP_USE_NEED_WAKEUP is used and the fill ring is empty so no buffer >>>> is allocated on RX side, allow RX NAPI to be descheduled. This avoids >>>> wasting CPU cycles on polling. Users will be notified and they need to >>>> make a wakeup call after refilling the ring. >>>> >>>> Signed-off-by: Bui Quang Minh >>>> --- >>>> drivers/net/virtio_net.c | 38 ++++++++++++++++++++++++++++++-------- >>>> 1 file changed, 30 insertions(+), 8 deletions(-) >>>> >>>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>>> index db88dcaefb20..494acc904b2c 100644 >>>> --- a/drivers/net/virtio_net.c >>>> +++ b/drivers/net/virtio_net.c >>>> @@ -1454,8 +1454,19 @@ static int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct receive_queue >>>> xsk_buffs = rq->xsk_buffs; >>>> >>>> num = xsk_buff_alloc_batch(pool, xsk_buffs, rq->vq->num_free); >>>> - if (!num) >>>> + if (!num) { >>>> + if (xsk_uses_need_wakeup(pool)) { >>>> + xsk_set_rx_need_wakeup(pool); >>>> + /* Return 0 instead of -ENOMEM so that NAPI is >>>> + * descheduled. >>>> + */ >>>> + return 0; >>>> + } >>>> + >>>> return -ENOMEM; >>>> + } else { >>>> + xsk_clear_rx_need_wakeup(pool); >>>> + } >>>> >>>> len = xsk_pool_get_rx_frame_size(pool) + vi->hdr_len; >>>> >>>> @@ -1588,20 +1599,21 @@ static bool virtnet_xsk_xmit(struct send_queue *sq, struct xsk_buff_pool *pool, >>>> return sent; >>>> } >>>> >>>> -static void xsk_wakeup(struct send_queue *sq) >>>> +static void xsk_wakeup(struct napi_struct *napi, struct virtqueue *vq) >>>> { >>>> - if (napi_if_scheduled_mark_missed(&sq->napi)) >>>> + if (napi_if_scheduled_mark_missed(napi)) >>>> return; >>>> >>>> local_bh_disable(); >>>> - virtqueue_napi_schedule(&sq->napi, sq->vq); >>>> + virtqueue_napi_schedule(napi, vq); >>>> local_bh_enable(); >>>> } >>>> >>>> static int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag) >>>> { >>>> struct virtnet_info *vi = netdev_priv(dev); >>>> - struct send_queue *sq; >>>> + struct napi_struct *napi; >>>> + struct virtqueue *vq; >>>> >>>> if (!netif_running(dev)) >>>> return -ENETDOWN; >>>> @@ -1609,9 +1621,19 @@ static int virtnet_xsk_wakeup(struct net_device *dev, u32 qid, u32 flag) >>>> if (qid >= vi->curr_queue_pairs) >>>> return -EINVAL; >>>> >>>> - sq = &vi->sq[qid]; >>>> + if (flag == XDP_WAKEUP_TX) { >>> Better use &? >> Sorry, I don't get your point. Can you elaborate more? > Oh, I meant using 'flag & XDP_WAKEUP_TX' is preferrable. IIUC, since > this patch provides a way to enable the RX flag, for virtio_net, this > flag can be set by TX and RX altogether? Please see this call trace: > xsk_poll()->xsk_wakeup(xs, pool->cached_need_wakeup). Oh, you're right. I'll fix it in the next version. Thanks, Quang Minh.