From: Longjun Tang <[email protected]> When busy-poll is active, napi_schedule_prep() returns false in virtqueue_napi_schedule(), so virtqueue_disable_cb() is skipped. The device may keep firing irqs until reaches virtqueue_napi_complete(). Under load (received == budget), it will lead to a large number of spurious interrupts.
Fix it by disabling the callback at the virtnet_poll() entry. This keeps the callback off while we poll and re-enable by virtqueue_napi_complete() when going idle. Signed-off-by: Longjun Tang <[email protected]> --- V1 -> V2: Remain agnostic to busy polling --- drivers/net/virtio_net.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index f4adcfee7a80..0a11f2b32500 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -3008,6 +3008,11 @@ static int virtnet_poll(struct napi_struct *napi, int budget) unsigned int xdp_xmit = 0; bool napi_complete; + /* Keep callbacks suppressed for the duration of this poll, + * busy-poll need. + */ + virtqueue_disable_cb(rq->vq); + virtnet_poll_cleantx(rq, budget); received = virtnet_receive(rq, budget, &xdp_xmit); -- 2.43.0
