netdev - RE: [PATCH net-next v2 4/6] virtio_net: Do DIM update for specified queue only

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Date: Thu, 28 Mar 2024 05:12:52 +0000
From: Dan Jurgens <danielj@...dia.com>
To: Heng Qi <hengqi@...ux.alibaba.com>, "netdev@...r.kernel.org"
	<netdev@...r.kernel.org>
CC: "mst@...hat.com" <mst@...hat.com>, "jasowang@...hat.com"
	<jasowang@...hat.com>, "xuanzhuo@...ux.alibaba.com"
	<xuanzhuo@...ux.alibaba.com>, "virtualization@...ts.linux.dev"
	<virtualization@...ts.linux.dev>, "davem@...emloft.net"
	<davem@...emloft.net>, "edumazet@...gle.com" <edumazet@...gle.com>,
	"kuba@...nel.org" <kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>,
	Jiri Pirko <jiri@...dia.com>
Subject: RE: [PATCH net-next v2 4/6] virtio_net: Do DIM update for specified
 queue only

> From: Heng Qi <hengqi@...ux.alibaba.com>
> Sent: Wednesday, March 27, 2024 11:57 PM
> To: Dan Jurgens <danielj@...dia.com>; netdev@...r.kernel.org
> Cc: mst@...hat.com; jasowang@...hat.com; xuanzhuo@...ux.alibaba.com;
> virtualization@...ts.linux.dev; davem@...emloft.net;
> edumazet@...gle.com; kuba@...nel.org; pabeni@...hat.com; Jiri Pirko
> <jiri@...dia.com>
> 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:
> > Since we no longer have to hold the RTNL lock here just do updates for
> > the specified queue.
> >
> > Signed-off-by: Daniel Jurgens <danielj@...dia.com>
> > ---
> >   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)
> >   	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
> 
> >
> > -		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",
> > -					 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",
> > +				 dev->name, qnum);
> > +		dim->state = DIM_START_MEASURE;
> >   	}
> >
> >   	rtnl_unlock();