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Date:   Mon, 24 Jul 2023 16:36:00 +0800
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Subject: Re: [PATCH net-next V3 3/4] virtio_net: support per queue interrupt
 coalesce command
To:     "Michael S. Tsirkin" <mst@redhat.com>
Cc:     jasowang@redhat.com, xuanzhuo@linux.alibaba.com,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, ast@kernel.org, daniel@iogearbox.net,
        hawk@kernel.org, john.fastabend@gmail.com, jiri@nvidia.com,
        dtatulea@nvidia.com, gavi@nvidia.com,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
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References: <20230724034048.51482-1-gavinl@nvidia.com>
 <20230724034048.51482-4-gavinl@nvidia.com>
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From:   Gavin Li <gavinl@nvidia.com>
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On 7/24/2023 3:32 PM, Michael S. Tsirkin wrote:
> On Mon, Jul 24, 2023 at 06:40:47AM +0300, Gavin Li wrote:
>> Add interrupt_coalesce config in send_queue and receive_queue to cache user
>> config.
>>
>> Send per virtqueue interrupt moderation config to underline device in order
>> to have more efficient interrupt moderation and cpu utilization of guest
>> VM.
>>
>> Signed-off-by: Gavin Li <gavinl@nvidia.com>
>> Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
>> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
>> Acked-by: Michael S. Tsirkin <mst@redhat.com>
>> ---
>>   drivers/net/virtio_net.c        | 120 ++++++++++++++++++++++++++++----
>>   include/uapi/linux/virtio_net.h |  14 ++++
>>   2 files changed, 122 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>> index 802ed21453f5..0c3ee1e26ece 100644
>> --- a/drivers/net/virtio_net.c
>> +++ b/drivers/net/virtio_net.c
>> @@ -144,6 +144,8 @@ struct send_queue {
>>   
>>   	struct virtnet_sq_stats stats;
>>   
>> +	struct virtnet_interrupt_coalesce intr_coal;
>> +
>>   	struct napi_struct napi;
>>   
>>   	/* Record whether sq is in reset state. */
>> @@ -161,6 +163,8 @@ struct receive_queue {
>>   
>>   	struct virtnet_rq_stats stats;
>>   
>> +	struct virtnet_interrupt_coalesce intr_coal;
>> +
>>   	/* Chain pages by the private ptr. */
>>   	struct page *pages;
>>   
>> @@ -212,6 +216,7 @@ struct control_buf {
>>   	struct virtio_net_ctrl_rss rss;
>>   	struct virtio_net_ctrl_coal_tx coal_tx;
>>   	struct virtio_net_ctrl_coal_rx coal_rx;
>> +	struct virtio_net_ctrl_coal_vq coal_vq;
>>   };
>>   
>>   struct virtnet_info {
>> @@ -3078,6 +3083,55 @@ static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
>>   	return 0;
>>   }
>>   
>> +static int virtnet_send_ctrl_coal_vq_cmd(struct virtnet_info *vi,
>> +					 u16 vqn, u32 max_usecs, u32 max_packets)
>> +{
>> +	struct scatterlist sgs;
>> +
>> +	vi->ctrl->coal_vq.vqn = cpu_to_le16(vqn);
>> +	vi->ctrl->coal_vq.coal.max_usecs = cpu_to_le32(max_usecs);
>> +	vi->ctrl->coal_vq.coal.max_packets = cpu_to_le32(max_packets);
>> +	sg_init_one(&sgs, &vi->ctrl->coal_vq, sizeof(vi->ctrl->coal_vq));
>> +
>> +	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
>> +				  VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET,
>> +				  &sgs))
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
>> +					  struct ethtool_coalesce *ec,
>> +					  u16 queue)
>> +{
>> +	int err;
>> +
>> +	if (ec->rx_coalesce_usecs || ec->rx_max_coalesced_frames) {
>> +		err = virtnet_send_ctrl_coal_vq_cmd(vi, rxq2vq(queue),
>> +						    ec->rx_coalesce_usecs,
>> +						    ec->rx_max_coalesced_frames);
>> +		if (err)
>> +			return err;
>> +		/* Save parameters */
>> +		vi->rq[queue].intr_coal.max_usecs = ec->rx_coalesce_usecs;
>> +		vi->rq[queue].intr_coal.max_packets = ec->rx_max_coalesced_frames;
>> +	}
>> +
>> +	if (ec->tx_coalesce_usecs || ec->tx_max_coalesced_frames) {
>> +		err = virtnet_send_ctrl_coal_vq_cmd(vi, txq2vq(queue),
>> +						    ec->tx_coalesce_usecs,
>> +						    ec->tx_max_coalesced_frames);
>> +		if (err)
>> +			return err;
>> +		/* Save parameters */
>> +		vi->sq[queue].intr_coal.max_usecs = ec->tx_coalesce_usecs;
>> +		vi->sq[queue].intr_coal.max_packets = ec->tx_max_coalesced_frames;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>>   static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
>>   {
>>   	/* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
>> @@ -3094,23 +3148,39 @@ static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
>>   }
>>   
>>   static int virtnet_set_coalesce_one(struct net_device *dev,
>> -				    struct ethtool_coalesce *ec)
>> +				    struct ethtool_coalesce *ec,
>> +				    bool per_queue,
>> +				    u32 queue)
>>   {
>>   	struct virtnet_info *vi = netdev_priv(dev);
>> -	int ret, i, napi_weight;
>> +	int queue_count = per_queue ? 1 : vi->max_queue_pairs;
>> +	int queue_number = per_queue ? queue : 0;
> 
> Actually can't we refactor this? This whole function is littered
> with if/else branches. just code it separately - the only
> common part is:
> 
>          napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
>          if (napi_weight ^ vi->sq[0].napi.weight) {
>                  if (dev->flags & IFF_UP)
>                          return -EBUSY;
>                  else
>                          update_napi = true;
>          }
> 
> so just move this to a helper and have two functions - global and
> per queue.
ACK
> 
> 
> 
>>   	bool update_napi = false;
>> +	int ret, i, napi_weight;
>> +
>> +	if (queue >= vi->max_queue_pairs)
>> +		return -EINVAL;
>>   
>>   	/* Can't change NAPI weight if the link is up */
>>   	napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
>> -	if (napi_weight ^ vi->sq[0].napi.weight) {
>> -		if (dev->flags & IFF_UP)
>> -			return -EBUSY;
>> -		else
>> +	for (i = queue_number; i < queue_count; i++) {
>> +		if (napi_weight ^ vi->sq[i].napi.weight) {
>> +			if (dev->flags & IFF_UP)
>> +				return -EBUSY;
>> +
>>   			update_napi = true;
>> +			/* All queues that belong to [queue_number, queue_count] will be
>> +			 * updated for the sake of simplicity, which might not be necessary
>> +			 */
>> +			queue_number = i;
>> +			break;
>> +		}
>>   	}
>>   
>> -	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
>> +	if (!per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
>>   		ret = virtnet_send_notf_coal_cmds(vi, ec);
>> +	else if (per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
>> +		ret = virtnet_send_notf_coal_vq_cmds(vi, ec, queue);
>>   	else
>>   		ret = virtnet_coal_params_supported(ec);
>>   
>> @@ -3118,7 +3188,7 @@ static int virtnet_set_coalesce_one(struct net_device *dev,
>>   		return ret;
>>   
>>   	if (update_napi) {
>> -		for (i = 0; i < vi->max_queue_pairs; i++)
>> +		for (i = queue_number; i < queue_count; i++)
>>   			vi->sq[i].napi.weight = napi_weight;
>>   	}
>>   
>> @@ -3130,19 +3200,29 @@ static int virtnet_set_coalesce(struct net_device *dev,
>>   				struct kernel_ethtool_coalesce *kernel_coal,
>>   				struct netlink_ext_ack *extack)
>>   {
>> -	return virtnet_set_coalesce_one(dev, ec);
>> +	return virtnet_set_coalesce_one(dev, ec, false, 0);
>>   }
>>   
>>   static int virtnet_get_coalesce_one(struct net_device *dev,
>> -				    struct ethtool_coalesce *ec)
>> +				    struct ethtool_coalesce *ec,
>> +				    bool per_queue,
>> +				    u32 queue)
>>   {
>>   	struct virtnet_info *vi = netdev_priv(dev);
>>   
>> -	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
>> +	if (queue >= vi->max_queue_pairs)
>> +		return -EINVAL;
>> +
>> +	if (!per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
>>   		ec->rx_coalesce_usecs = vi->intr_coal_rx.max_usecs;
>>   		ec->tx_coalesce_usecs = vi->intr_coal_tx.max_usecs;
>>   		ec->tx_max_coalesced_frames = vi->intr_coal_tx.max_packets;
>>   		ec->rx_max_coalesced_frames = vi->intr_coal_rx.max_packets;
>> +	} else if (per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
>> +		ec->rx_coalesce_usecs = vi->rq[queue].intr_coal.max_usecs;
>> +		ec->tx_coalesce_usecs = vi->sq[queue].intr_coal.max_usecs;
>> +		ec->tx_max_coalesced_frames = vi->sq[queue].intr_coal.max_packets;
>> +		ec->rx_max_coalesced_frames = vi->rq[queue].intr_coal.max_packets;
>>   	} else {
>>   		ec->rx_max_coalesced_frames = 1;
>>   
>> @@ -3158,7 +3238,21 @@ static int virtnet_get_coalesce(struct net_device *dev,
>>   				struct kernel_ethtool_coalesce *kernel_coal,
>>   				struct netlink_ext_ack *extack)
>>   {
>> -	return virtnet_get_coalesce_one(dev, ec);
>> +	return virtnet_get_coalesce_one(dev, ec, false, 0);
>> +}
>> +
>> +static int virtnet_set_per_queue_coalesce(struct net_device *dev,
>> +					  u32 queue,
>> +					  struct ethtool_coalesce *ec)
>> +{
>> +	return virtnet_set_coalesce_one(dev, ec, true, queue);
>> +}
>> +
>> +static int virtnet_get_per_queue_coalesce(struct net_device *dev,
>> +					  u32 queue,
>> +					  struct ethtool_coalesce *ec)
>> +{
>> +	return virtnet_get_coalesce_one(dev, ec, true, queue);
>>   }
>>   
>>   static void virtnet_init_settings(struct net_device *dev)
>> @@ -3291,6 +3385,8 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
>>   	.set_link_ksettings = virtnet_set_link_ksettings,
>>   	.set_coalesce = virtnet_set_coalesce,
>>   	.get_coalesce = virtnet_get_coalesce,
>> +	.set_per_queue_coalesce = virtnet_set_per_queue_coalesce,
>> +	.get_per_queue_coalesce = virtnet_get_per_queue_coalesce,
>>   	.get_rxfh_key_size = virtnet_get_rxfh_key_size,
>>   	.get_rxfh_indir_size = virtnet_get_rxfh_indir_size,
>>   	.get_rxfh = virtnet_get_rxfh,
>> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
>> index 12c1c9699935..cc65ef0f3c3e 100644
>> --- a/include/uapi/linux/virtio_net.h
>> +++ b/include/uapi/linux/virtio_net.h
>> @@ -56,6 +56,7 @@
>>   #define VIRTIO_NET_F_MQ	22	/* Device supports Receive Flow
>>   					 * Steering */
>>   #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>> +#define VIRTIO_NET_F_VQ_NOTF_COAL 52	/* Device supports virtqueue notification coalescing */
>>   #define VIRTIO_NET_F_NOTF_COAL	53	/* Device supports notifications coalescing */
>>   #define VIRTIO_NET_F_GUEST_USO4	54	/* Guest can handle USOv4 in. */
>>   #define VIRTIO_NET_F_GUEST_USO6	55	/* Guest can handle USOv6 in. */
>> @@ -391,5 +392,18 @@ struct virtio_net_ctrl_coal_rx {
>>   };
>>   
>>   #define VIRTIO_NET_CTRL_NOTF_COAL_RX_SET		1
>> +#define VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET		2
>> +#define VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET		3
>> +
>> +struct virtio_net_ctrl_coal {
>> +	__le32 max_packets;
>> +	__le32 max_usecs;
>> +};
>> +
>> +struct  virtio_net_ctrl_coal_vq {
>> +	__le16 vqn;
>> +	__le16 reserved;
>> +	struct virtio_net_ctrl_coal coal;
>> +};
>>   
>>   #endif /* _UAPI_LINUX_VIRTIO_NET_H */
>> -- 
>> 2.39.1
>