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Tsirkin" , Shannon Nelson References: <20230720083839.481487-1-jasowang@redhat.com> <20230720083839.481487-3-jasowang@redhat.com> <20230720170001-mutt-send-email-mst@kernel.org> From: Maxime Coquelin In-Reply-To: <20230720170001-mutt-send-email-mst@kernel.org> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Cc: xuanzhuo@linux.alibaba.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On 7/20/23 23:02, Michael S. Tsirkin wrote: > On Thu, Jul 20, 2023 at 01:26:20PM -0700, Shannon Nelson wrote: >> On 7/20/23 1:38 AM, Jason Wang wrote: >>> >>> Adding cond_resched() to the command waiting loop for a better >>> co-operation with the scheduler. This allows to give CPU a breath to >>> run other task(workqueue) instead of busy looping when preemption is >>> not allowed on a device whose CVQ might be slow. >>> >>> Signed-off-by: Jason Wang >> >> This still leaves hung processes, but at least it doesn't pin the CPU any >> more. Thanks. >> Reviewed-by: Shannon Nelson >> > > I'd like to see a full solution > 1- block until interrupt Would it make sense to also have a timeout? And when timeout expires, set FAILED bit in device status? > 2- still handle surprise removal correctly by waking in that case > > > >>> --- >>> drivers/net/virtio_net.c | 4 +++- >>> 1 file changed, 3 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c >>> index 9f3b1d6ac33d..e7533f29b219 100644 >>> --- a/drivers/net/virtio_net.c >>> +++ b/drivers/net/virtio_net.c >>> @@ -2314,8 +2314,10 @@ static bool virtnet_send_command(struct virtnet_info *vi, u8 class, u8 cmd, >>> * into the hypervisor, so the request should be handled immediately. >>> */ >>> while (!virtqueue_get_buf(vi->cvq, &tmp) && >>> - !virtqueue_is_broken(vi->cvq)) >>> + !virtqueue_is_broken(vi->cvq)) { >>> + cond_resched(); >>> cpu_relax(); >>> + } >>> >>> return vi->ctrl->status == VIRTIO_NET_OK; >>> } >>> -- >>> 2.39.3 >>> >>> _______________________________________________ >>> Virtualization mailing list >>> Virtualization@lists.linux-foundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/virtualization > _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization