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authorToshiaki Makita <makita.toshiaki@lab.ntt.co.jp>2017-12-07 13:15:15 +0900
committerDavid S. Miller <davem@davemloft.net>2017-12-08 13:18:40 -0500
commitfdaa767aefc1685f9a41e91f447c9aea94103df6 (patch)
tree02bd2c5cabccc11c38001e1d8375d426240e8333 /drivers/net/virtio_net.c
parent62cd277039a3413604f486f0ca87faec810d7bb7 (diff)
virtio_net: Disable interrupts if napi_complete_done rescheduled napi
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 <makita.toshiaki@lab.ntt.co.jp> Acked-by: Michael S. Tsirkin <mst@redhat.com> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/virtio_net.c')
-rw-r--r--drivers/net/virtio_net.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 19a985ef9104..c0db48de7bf9 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -261,9 +261,12 @@ static void virtqueue_napi_complete(struct napi_struct *napi,
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)