[PATCH RFC net-next] virtio_net: refill buffer right after being used
From: Shirley Ma <hidden>
Date: 2011-07-29 22:44:16
Also in:
kvm, netdev
Subsystem:
networking drivers, the rest, virtio net driver · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds, "Michael S. Tsirkin", Jason Wang, Eugenio Pérez
To even the latency, refill buffer right after being used. Sign-off-by: Shirley Ma [off-list ref] ---
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0c7321c..c8201d4 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c@@ -429,6 +429,22 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi, gfp_t gfp) return err; } +static bool fill_one(struct virtio_net *vi, gfp_t gfp) +{ + int err; + + if (vi->mergeable_rx_bufs) + err = add_recvbuf_mergeable(vi, gfp); + else if (vi->big_packets) + err = add_recvbuf_big(vi, gfp); + else + err = add_recvbuf_small(vi, gfp); + + if (err >= 0) + ++vi->num; + return err; +} + /* Returns false if we couldn't fill entirely (OOM). */ static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp) {
@@ -436,17 +452,10 @@ static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp) bool oom; do { - if (vi->mergeable_rx_bufs) - err = add_recvbuf_mergeable(vi, gfp); - else if (vi->big_packets) - err = add_recvbuf_big(vi, gfp); - else - err = add_recvbuf_small(vi, gfp); - + err = fill_one(vi, gfp); oom = err == -ENOMEM; if (err < 0) break; - ++vi->num; } while (err > 0); if (unlikely(vi->num > vi->max)) vi->max = vi->num;
@@ -506,13 +515,13 @@ again: receive_buf(vi->dev, buf, len); --vi->num; received++; - } - - if (vi->num < vi->max / 2) { - if (!try_fill_recv(vi, GFP_ATOMIC)) + if (fill_one(vi, GFP_ATOMIC) < 0) schedule_delayed_work(&vi->refill, 0); } + /* notify buffers are refilled */ + virtqueue_kick(vi->rvq); + /* Out of packets? */ if (received < budget) { napi_complete(napi);