This change makes ring buffer reclaim threshold num_free configurable for better performance, while it's hard coded as 1/2 * queue now.
According to our test with qemu + dpdk, packet dropping happens when the guest is not able to provide free buffer in avail ring timely.
Smaller value of num_free does decrease the number of packet dropping during our test as it makes virtio_net reclaim buffer earlier.
At least, we should leave the value changeable to user while the default value as 1/2 * queue is kept.
Signed-off-by: jiangkidd <jiangkidd@xxxxxxxxxxx>
---
drivers/net/virtio_net.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 0d4115c9e20b..bc190dec6084 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -26,6 +26,9 @@
static int napi_weight = NAPI_POLL_WEIGHT;
module_param(napi_weight, int, 0444);
+static int min_numfree;
+module_param(min_numfree, int, 0444);
+
static bool csum = true, gso = true, napi_tx;
module_param(csum, bool, 0444);
module_param(gso, bool, 0444);
@@ -1315,6 +1318,9 @@ static int virtnet_receive(struct receive_queue *rq, int budget,
void *buf;
int i;
+ if (!min_numfree)
+ min_numfree = virtqueue_get_vring_size(rq->vq) / 2;
+
if (!vi->big_packets || vi->mergeable_rx_bufs) {
void *ctx;
@@ -1331,7 +1337,7 @@ static int virtnet_receive(struct receive_queue *rq, int budget,
}
}
- if (rq->vq->num_free > virtqueue_get_vring_size(rq->vq) / 2) {
+ if (rq->vq->num_free > min_numfree) {
if (!try_fill_recv(vi, rq, GFP_ATOMIC))
schedule_delayed_work(&vi->refill, 0);
}
--
2.11.0
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