From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:49172 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753320AbeCPOsv (ORCPT ); Fri, 16 Mar 2018 10:48:51 -0400 Subject: Patch "virtio_net: Disable interrupts if napi_complete_done rescheduled napi" has been added to the 4.14-stable tree To: makita.toshiaki@lab.ntt.co.jp, alexander.levin@microsoft.com, davem@davemloft.net, gregkh@linuxfoundation.org, jasowang@redhat.com, mst@redhat.com Cc: , From: Date: Fri, 16 Mar 2018 15:47:19 +0100 Message-ID: <15212116392465@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled virtio_net: Disable interrupts if napi_complete_done rescheduled napi to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: virtio_net-disable-interrupts-if-napi_complete_done-rescheduled-napi.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Fri Mar 16 15:43:17 CET 2018 From: Toshiaki Makita Date: Thu, 7 Dec 2017 13:15:15 +0900 Subject: virtio_net: Disable interrupts if napi_complete_done rescheduled napi From: Toshiaki Makita [ Upstream commit fdaa767aefc1685f9a41e91f447c9aea94103df6 ] Since commit 39e6c8208d7b ("net: solve a NAPI race") napi has been able to be rescheduled within napi_complete_done() even in non-busypoll case, but virtnet_poll() always enabled interrupts before complete, and when napi was rescheduled within napi_complete_done() it did not disable interrupts. This caused more interrupts when event idx is disabled. According to commit cbdadbbf0c79 ("virtio_net: fix race in RX VQ processing") we cannot place virtqueue_enable_cb_prepare() after NAPI_STATE_SCHED is cleared, so disable interrupts again if napi_complete_done() returned false. Tested with vhost-user of OVS 2.7 on host, which does not have the event idx feature. * Before patch: $ netperf -t UDP_STREAM -H 192.168.150.253 -l 60 -- -m 1472 MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.150.253 () port 0 AF_INET Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 1472 60.00 32763206 0 6430.32 212992 60.00 23384299 4589.56 Interrupts on guest: 9872369 Packets/interrupt: 2.37 * After patch $ netperf -t UDP_STREAM -H 192.168.150.253 -l 60 -- -m 1472 MIGRATED UDP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.150.253 () port 0 AF_INET Socket Message Elapsed Messages Size Size Time Okay Errors Throughput bytes bytes secs # # 10^6bits/sec 212992 1472 60.00 32794646 0 6436.49 212992 60.00 32793501 6436.27 Interrupts on guest: 4941299 Packets/interrupt: 6.64 Signed-off-by: Toshiaki Makita Acked-by: Michael S. Tsirkin Acked-by: Jason Wang Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/net/virtio_net.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -260,9 +260,12 @@ static void virtqueue_napi_complete(stru int opaque; opaque = virtqueue_enable_cb_prepare(vq); - if (napi_complete_done(napi, processed) && - unlikely(virtqueue_poll(vq, opaque))) - virtqueue_napi_schedule(napi, vq); + if (napi_complete_done(napi, processed)) { + if (unlikely(virtqueue_poll(vq, opaque))) + virtqueue_napi_schedule(napi, vq); + } else { + virtqueue_disable_cb(vq); + } } static void skb_xmit_done(struct virtqueue *vq) Patches currently in stable-queue which might be from makita.toshiaki@lab.ntt.co.jp are queue-4.14/virtio_net-disable-interrupts-if-napi_complete_done-rescheduled-napi.patch