From: Heng Qi <redacted>
Sent: Wednesday, March 27, 2024 11:57 PM
To: Dan Jurgens <redacted>; netdev@vger.kernel.org
Cc: mst@redhat.com; jasowang@redhat.com; xuanzhuo@linux.alibaba.com;
virtualization@lists.linux.dev; davem@davemloft.net;
edumazet@google.com; kuba@kernel.org; pabeni@redhat.com; Jiri Pirko
[off-list ref]
Subject: Re: [PATCH net-next v2 4/6] virtio_net: Do DIM update for specified
queue only



在 2024/3/28 下午12:47, Daniel Jurgens 写道:

quoted

Since we no longer have to hold the RTNL lock here just do updates for
the specified queue.

Signed-off-by: Daniel Jurgens <redacted>
---
  drivers/net/virtio_net.c | 38 ++++++++++++++------------------------
  1 file changed, 14 insertions(+), 24 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index

b9298544b1b5..9c4bfb1eb15c 100644

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -3596,36 +3596,26 @@ static void virtnet_rx_dim_work(struct

work_struct *work)

quoted

  	struct virtnet_info *vi = rq->vq->vdev->priv;
  	struct net_device *dev = vi->dev;
  	struct dim_cq_moder update_moder;
-	int i, qnum, err;
+	int qnum, err;

  	if (!rtnl_trylock())
  		return;

-	/* Each rxq's work is queued by "net_dim()->schedule_work()"
-	 * in response to NAPI traffic changes. Note that dim->profile_ix
-	 * for each rxq is updated prior to the queuing action.
-	 * So we only need to traverse and update profiles for all rxqs
-	 * in the work which is holding rtnl_lock.
-	 */
-	for (i = 0; i < vi->curr_queue_pairs; i++) {
-		rq = &vi->rq[i];
-		dim = &rq->dim;
-		qnum = rq - vi->rq;
+	qnum = rq - vi->rq;

-		if (!rq->dim_enabled)
-			continue;
+	if (!rq->dim_enabled)
+		continue;

?

continue what?

Sorry, messed this up when I was testing the patches and put the fix for the continue in the lock patch.

For the lock code, please pass the test. It's important.

I did some bench testing. I'll do more and send a new set early next week.

Regards,
Heng

quoted

-		update_moder = net_dim_get_rx_moderation(dim->mode,

dim->profile_ix);

quoted

-		if (update_moder.usec != rq->intr_coal.max_usecs ||
-		    update_moder.pkts != rq->intr_coal.max_packets) {
-			err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, qnum,
-

update_moder.usec,

quoted

-

update_moder.pkts);

quoted

-			if (err)
-				pr_debug("%s: Failed to send dim

parameters on rxq%d\n",

quoted

-					 dev->name, qnum);
-			dim->state = DIM_START_MEASURE;
-		}
+	update_moder = net_dim_get_rx_moderation(dim->mode, dim-
profile_ix);
+	if (update_moder.usec != rq->intr_coal.max_usecs ||
+	    update_moder.pkts != rq->intr_coal.max_packets) {
+		err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, qnum,
+						       update_moder.usec,
+						       update_moder.pkts);
+		if (err)
+			pr_debug("%s: Failed to send dim parameters on

rxq%d\n",

quoted

+				 dev->name, qnum);
+		dim->state = DIM_START_MEASURE;
  	}

  	rtnl_unlock();