[PATCH net-next 0/3] veth: XDP stats improvement

[PATCH net-next 0/3] veth: XDP stats improvement

[Toshiaki Makita]

ndo_xdp_xmit in veth did not update packet counters as described in [1].
Also, current implementation only updates counters on tx side so rx side
events like XDP_DROP were not collected.
This series implements the missing accounting as well as support for
ethtool per-queue stats in veth.

Patch 1: Update drop counter in ndo_xdp_xmit.
Patch 2: Update packet and byte counters for all XDP path, and drop
         counter on XDP_DROP.
Patch 3: Support per-queue ethtool stats for XDP counters.

Note that counters are maintained on per-queue basis for XDP but not
otherwise (per-cpu and atomic as before). This is because 1) tx path in
veth is essentially lockless so we cannot update per-queue stats on tx,
and 2) rx path is net core routine (process_backlog) which cannot update
per-queue based stats when XDP is disabled. On the other hand there are
real rxqs and napi handlers for veth XDP, so update per-queue stats on
rx for XDP packets, and use them to calculate tx counters as well,
contrary to the existing non-XDP counters.

[1] https://patchwork.ozlabs.org/cover/953071/#1967449

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>

Toshiaki Makita (3):
  veth: Account for packet drops in ndo_xdp_xmit
  veth: Account for XDP packet statistics on rx side
  veth: Add ethtool statistics support for XDP

 drivers/net/veth.c | 175 ++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 147 insertions(+), 28 deletions(-)

-- 
1.8.3.1

[PATCH net-next 1/3] veth: Account for packet drops in ndo_xdp_xmit

[Toshiaki Makita]

Use existing atomic drop counter. Since drop path is really an
exceptional case here, I'm thinking atomic ops would not hurt the
performance.
XDP packets and bytes are not counted in ndo_xdp_xmit, but will be
accounted on rx side by the following commit.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
---
 drivers/net/veth.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 224c56a..452193f2 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -308,16 +308,20 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
 {
 	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
 	struct net_device *rcv;
+	int i, ret, drops = n;
 	unsigned int max_len;
 	struct veth_rq *rq;
-	int i, drops = 0;
 
-	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
-		return -EINVAL;
+	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
+		ret = -EINVAL;
+		goto drop;
+	}
 
 	rcv = rcu_dereference(priv->peer);
-	if (unlikely(!rcv))
-		return -ENXIO;
+	if (unlikely(!rcv)) {
+		ret = -ENXIO;
+		goto drop;
+	}
 
 	rcv_priv = netdev_priv(rcv);
 	rq = &rcv_priv->rq[veth_select_rxq(rcv)];
@@ -325,9 +329,12 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
 	 * side. This means an XDP program is loaded on the peer and the peer
 	 * device is up.
 	 */
-	if (!rcu_access_pointer(rq->xdp_prog))
-		return -ENXIO;
+	if (!rcu_access_pointer(rq->xdp_prog)) {
+		ret = -ENXIO;
+		goto drop;
+	}
 
+	drops = 0;
 	max_len = rcv->mtu + rcv->hard_header_len + VLAN_HLEN;
 
 	spin_lock(&rq->xdp_ring.producer_lock);
@@ -346,7 +353,14 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
 	if (flags & XDP_XMIT_FLUSH)
 		__veth_xdp_flush(rq);
 
-	return n - drops;
+	if (likely(!drops))
+		return n;
+
+	ret = n - drops;
+drop:
+	atomic64_add(drops, &priv->dropped);
+
+	return ret;
 }
 
 static void veth_xdp_flush(struct net_device *dev)
-- 
1.8.3.1

[PATCH net-next 2/3] veth: Account for XDP packet statistics on rx side

[Toshiaki Makita]

On XDP path veth has napi handler so we can collect statistics on
per-queue basis for XDP.

By this change now we can collect XDP_DROP drop count as well as packets
and bytes coming through ndo_xdp_xmit. Packet counters shown by
"ip -s link", sysfs stats or /proc/net/dev is now correct for XDP.

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
---
 drivers/net/veth.c | 97 ++++++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 79 insertions(+), 18 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 452193f2..68bb93d 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -37,11 +37,19 @@
 #define VETH_XDP_TX		BIT(0)
 #define VETH_XDP_REDIR		BIT(1)
 
+struct veth_rq_stats {
+	u64			xdp_packets;
+	u64			xdp_bytes;
+	u64			xdp_drops;
+	struct u64_stats_sync	syncp;
+};
+
 struct veth_rq {
 	struct napi_struct	xdp_napi;
 	struct net_device	*dev;
 	struct bpf_prog __rcu	*xdp_prog;
 	struct xdp_mem_info	xdp_mem;
+	struct veth_rq_stats	stats;
 	bool			rx_notify_masked;
 	struct ptr_ring		xdp_ring;
 	struct xdp_rxq_info	xdp_rxq;
@@ -211,12 +219,14 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	skb_tx_timestamp(skb);
 	if (likely(veth_forward_skb(rcv, skb, rq, rcv_xdp) == NET_RX_SUCCESS)) {
-		struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
+		if (!rcv_xdp) {
+			struct pcpu_lstats *stats = this_cpu_ptr(dev->lstats);
 
-		u64_stats_update_begin(&stats->syncp);
-		stats->bytes += length;
-		stats->packets++;
-		u64_stats_update_end(&stats->syncp);
+			u64_stats_update_begin(&stats->syncp);
+			stats->bytes += length;
+			stats->packets++;
+			u64_stats_update_end(&stats->syncp);
+		}
 	} else {
 drop:
 		atomic64_inc(&priv->dropped);
@@ -230,7 +240,7 @@ static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
 	return NETDEV_TX_OK;
 }
 
-static u64 veth_stats_one(struct pcpu_lstats *result, struct net_device *dev)
+static u64 veth_stats_tx(struct pcpu_lstats *result, struct net_device *dev)
 {
 	struct veth_priv *priv = netdev_priv(dev);
 	int cpu;
@@ -253,23 +263,58 @@ static u64 veth_stats_one(struct pcpu_lstats *result, struct net_device *dev)
 	return atomic64_read(&priv->dropped);
 }
 
+static void veth_stats_rx(struct veth_rq_stats *result, struct net_device *dev)
+{
+	struct veth_priv *priv = netdev_priv(dev);
+	int i;
+
+	result->xdp_packets = 0;
+	result->xdp_bytes = 0;
+	result->xdp_drops = 0;
+	for (i = 0; i < dev->num_rx_queues; i++) {
+		struct veth_rq_stats *stats = &priv->rq[i].stats;
+		u64 packets, bytes, drops;
+		unsigned int start;
+
+		do {
+			start = u64_stats_fetch_begin_irq(&stats->syncp);
+			packets = stats->xdp_packets;
+			bytes = stats->xdp_bytes;
+			drops = stats->xdp_drops;
+		} while (u64_stats_fetch_retry_irq(&stats->syncp, start));
+		result->xdp_packets += packets;
+		result->xdp_bytes += bytes;
+		result->xdp_drops += drops;
+	}
+}
+
 static void veth_get_stats64(struct net_device *dev,
 			     struct rtnl_link_stats64 *tot)
 {
 	struct veth_priv *priv = netdev_priv(dev);
 	struct net_device *peer;
-	struct pcpu_lstats one;
+	struct veth_rq_stats rx;
+	struct pcpu_lstats tx;
+
+	tot->tx_dropped = veth_stats_tx(&tx, dev);
+	tot->tx_bytes = tx.bytes;
+	tot->tx_packets = tx.packets;
 
-	tot->tx_dropped = veth_stats_one(&one, dev);
-	tot->tx_bytes = one.bytes;
-	tot->tx_packets = one.packets;
+	veth_stats_rx(&rx, dev);
+	tot->rx_dropped = rx.xdp_drops;
+	tot->rx_bytes = rx.xdp_bytes;
+	tot->rx_packets = rx.xdp_packets;
 
 	rcu_read_lock();
 	peer = rcu_dereference(priv->peer);
 	if (peer) {
-		tot->rx_dropped = veth_stats_one(&one, peer);
-		tot->rx_bytes = one.bytes;
-		tot->rx_packets = one.packets;
+		tot->rx_dropped += veth_stats_tx(&tx, peer);
+		tot->rx_bytes += tx.bytes;
+		tot->rx_packets += tx.packets;
+
+		veth_stats_rx(&rx, peer);
+		tot->tx_bytes += rx.xdp_bytes;
+		tot->tx_packets += rx.xdp_packets;
 	}
 	rcu_read_unlock();
 }
@@ -609,28 +654,42 @@ static struct sk_buff *veth_xdp_rcv_skb(struct veth_rq *rq, struct sk_buff *skb,
 
 static int veth_xdp_rcv(struct veth_rq *rq, int budget, unsigned int *xdp_xmit)
 {
-	int i, done = 0;
+	int i, done = 0, drops = 0, bytes = 0;
 
 	for (i = 0; i < budget; i++) {
 		void *ptr = __ptr_ring_consume(&rq->xdp_ring);
+		unsigned int xdp_xmit_one = 0;
 		struct sk_buff *skb;
 
 		if (!ptr)
 			break;
 
 		if (veth_is_xdp_frame(ptr)) {
-			skb = veth_xdp_rcv_one(rq, veth_ptr_to_xdp(ptr),
-					       xdp_xmit);
+			struct xdp_frame *frame = veth_ptr_to_xdp(ptr);
+
+			bytes += frame->len;
+			skb = veth_xdp_rcv_one(rq, frame, &xdp_xmit_one);
 		} else {
-			skb = veth_xdp_rcv_skb(rq, ptr, xdp_xmit);
+			skb = ptr;
+			bytes += skb->len;
+			skb = veth_xdp_rcv_skb(rq, skb, &xdp_xmit_one);
 		}
+		*xdp_xmit |= xdp_xmit_one;
 
 		if (skb)
 			napi_gro_receive(&rq->xdp_napi, skb);
+		else if (!xdp_xmit_one)
+			drops++;
 
 		done++;
 	}
 
+	u64_stats_update_begin(&rq->stats.syncp);
+	rq->stats.xdp_packets += done;
+	rq->stats.xdp_bytes += bytes;
+	rq->stats.xdp_drops += drops;
+	u64_stats_update_end(&rq->stats.syncp);
+
 	return done;
 }
 
@@ -821,8 +880,10 @@ static int veth_alloc_queues(struct net_device *dev)
 	if (!priv->rq)
 		return -ENOMEM;
 
-	for (i = 0; i < dev->num_rx_queues; i++)
+	for (i = 0; i < dev->num_rx_queues; i++) {
 		priv->rq[i].dev = dev;
+		u64_stats_init(&priv->rq[i].stats.syncp);
+	}
 
 	return 0;
 }
-- 
1.8.3.1

[PATCH net-next 3/3] veth: Add ethtool statistics support for XDP

[Toshiaki Makita]

Expose per-queue stats for ethtool -S.
As there are only rx queues, and rx queues are used only when XDP is
used, per-queue counters are only rx XDP ones.

Example:

$ ethtool -S veth0
NIC statistics:
     peer_ifindex: 11
     rx_queue_0_xdp_packets: 28601434
     rx_queue_0_xdp_bytes: 1716086040
     rx_queue_0_xdp_drops: 28601434
     rx_queue_1_xdp_packets: 17873050
     rx_queue_1_xdp_bytes: 1072383000
     rx_queue_1_xdp_drops: 17873050

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
---
 drivers/net/veth.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 68bb93d..890fa5b 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -67,6 +67,21 @@ struct veth_priv {
  * ethtool interface
  */
 
+struct veth_q_stat_desc {
+	char	desc[ETH_GSTRING_LEN];
+	size_t	offset;
+};
+
+#define VETH_RQ_STAT(m)	offsetof(struct veth_rq_stats, m)
+
+static const struct veth_q_stat_desc veth_rq_stats_desc[] = {
+	{ "xdp_packets",	VETH_RQ_STAT(xdp_packets) },
+	{ "xdp_bytes",		VETH_RQ_STAT(xdp_bytes) },
+	{ "xdp_drops",		VETH_RQ_STAT(xdp_drops) },
+};
+
+#define VETH_RQ_STATS_LEN	ARRAY_SIZE(veth_rq_stats_desc)
+
 static struct {
 	const char string[ETH_GSTRING_LEN];
 } ethtool_stats_keys[] = {
@@ -91,9 +106,20 @@ static void veth_get_drvinfo(struct net_device *dev, struct ethtool_drvinfo *inf
 
 static void veth_get_strings(struct net_device *dev, u32 stringset, u8 *buf)
 {
+	char *p = (char *)buf;
+	int i, j;
+
 	switch(stringset) {
 	case ETH_SS_STATS:
-		memcpy(buf, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
+		memcpy(p, &ethtool_stats_keys, sizeof(ethtool_stats_keys));
+		p += sizeof(ethtool_stats_keys);
+		for (i = 0; i < dev->real_num_rx_queues; i++) {
+			for (j = 0; j < VETH_RQ_STATS_LEN; j++) {
+				snprintf(p, ETH_GSTRING_LEN, "rx_queue_%u_%s",
+					 i, veth_rq_stats_desc[j].desc);
+				p += ETH_GSTRING_LEN;
+			}
+		}
 		break;
 	}
 }
@@ -102,7 +128,8 @@ static int veth_get_sset_count(struct net_device *dev, int sset)
 {
 	switch (sset) {
 	case ETH_SS_STATS:
-		return ARRAY_SIZE(ethtool_stats_keys);
+		return ARRAY_SIZE(ethtool_stats_keys) +
+		       VETH_RQ_STATS_LEN * dev->real_num_rx_queues;
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -113,8 +140,25 @@ static void veth_get_ethtool_stats(struct net_device *dev,
 {
 	struct veth_priv *priv = netdev_priv(dev);
 	struct net_device *peer = rtnl_dereference(priv->peer);
+	int i, j, idx;
 
 	data[0] = peer ? peer->ifindex : 0;
+	idx = 1;
+	for (i = 0; i < dev->real_num_rx_queues; i++) {
+		const struct veth_rq_stats *rq_stats = &priv->rq[i].stats;
+		const void *stats_base = (void *)rq_stats;
+		unsigned int start;
+		size_t offset;
+
+		do {
+			start = u64_stats_fetch_begin_irq(&rq_stats->syncp);
+			for (j = 0; j < VETH_RQ_STATS_LEN; j++) {
+				offset = veth_rq_stats_desc[j].offset;
+				data[idx + j] = *(u64 *)(stats_base + offset);
+			}
+		} while (u64_stats_fetch_retry_irq(&rq_stats->syncp, start));
+		idx += VETH_RQ_STATS_LEN;
+	}
 }
 
 static int veth_get_ts_info(struct net_device *dev,
-- 
1.8.3.1

Re: [PATCH net-next 1/3] veth: Account for packet drops in ndo_xdp_xmit

[Jesper Dangaard Brouer]

On Thu, 11 Oct 2018 18:36:48 +0900
Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> wrote:

> Use existing atomic drop counter. Since drop path is really an
> exceptional case here, I'm thinking atomic ops would not hurt the
> performance.

Hmm... we try very hard not to add atomic ops to XDP code path. The
XDP_DROP case is also considered hot-path.  In below code, the
atomic64_add happens for a bulk of dropped packets (currently up-to
16), so it might be okay.

> XDP packets and bytes are not counted in ndo_xdp_xmit, but will be
> accounted on rx side by the following commit.
> 
> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
> ---
>  drivers/net/veth.c | 30 ++++++++++++++++++++++--------
>  1 file changed, 22 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
> index 224c56a..452193f2 100644
> --- a/drivers/net/veth.c
> +++ b/drivers/net/veth.c
> @@ -308,16 +308,20 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
>  {
>  	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
>  	struct net_device *rcv;
> +	int i, ret, drops = n;
>  	unsigned int max_len;
>  	struct veth_rq *rq;
> -	int i, drops = 0;
>  
> -	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
> -		return -EINVAL;
> +	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
> +		ret = -EINVAL;
> +		goto drop;
> +	}
>  
>  	rcv = rcu_dereference(priv->peer);
> -	if (unlikely(!rcv))
> -		return -ENXIO;
> +	if (unlikely(!rcv)) {
> +		ret = -ENXIO;
> +		goto drop;
> +	}
>  
>  	rcv_priv = netdev_priv(rcv);
>  	rq = &rcv_priv->rq[veth_select_rxq(rcv)];
> @@ -325,9 +329,12 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
>  	 * side. This means an XDP program is loaded on the peer and the peer
>  	 * device is up.
>  	 */
> -	if (!rcu_access_pointer(rq->xdp_prog))
> -		return -ENXIO;
> +	if (!rcu_access_pointer(rq->xdp_prog)) {
> +		ret = -ENXIO;
> +		goto drop;
> +	}
>  
> +	drops = 0;
>  	max_len = rcv->mtu + rcv->hard_header_len + VLAN_HLEN;
>  
>  	spin_lock(&rq->xdp_ring.producer_lock);
> @@ -346,7 +353,14 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
>  	if (flags & XDP_XMIT_FLUSH)
>  		__veth_xdp_flush(rq);
>  
> -	return n - drops;
> +	if (likely(!drops))
> +		return n;
> +
> +	ret = n - drops;
> +drop:
> +	atomic64_add(drops, &priv->dropped);
> +
> +	return ret;
>  }
>  
>  static void veth_xdp_flush(struct net_device *dev)



-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer

Re: [PATCH net-next 1/3] veth: Account for packet drops in ndo_xdp_xmit

[Toshiaki Makita]

On 18/10/13 (土) 16:48, Jesper Dangaard Brouer wrote:
> On Thu, 11 Oct 2018 18:36:48 +0900
> Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> wrote:
> 
>> Use existing atomic drop counter. Since drop path is really an
>> exceptional case here, I'm thinking atomic ops would not hurt the
>> performance.
> 
> Hmm... we try very hard not to add atomic ops to XDP code path. The
> XDP_DROP case is also considered hot-path.  In below code, the
> atomic64_add happens for a bulk of dropped packets (currently up-to
> 16), so it might be okay.

Yes, this happens only once in a bulk sending.
Note that this drop does not include XDP_DROP. This drop is counted when
- ndo_xdp_xmit "flags" arg is invalid
- peer is detached
- XDP is not loaded on peer
- XDP ring (256 slots) overflow
So really exceptional. XDP_DROP is counted per-queue basis (non-atomic) 
in the patch 2/3.

Toshiaki Makita

> 
>> XDP packets and bytes are not counted in ndo_xdp_xmit, but will be
>> accounted on rx side by the following commit.
>>
>> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
>> ---
>>   drivers/net/veth.c | 30 ++++++++++++++++++++++--------
>>   1 file changed, 22 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
>> index 224c56a..452193f2 100644
>> --- a/drivers/net/veth.c
>> +++ b/drivers/net/veth.c
>> @@ -308,16 +308,20 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
>>   {
>>   	struct veth_priv *rcv_priv, *priv = netdev_priv(dev);
>>   	struct net_device *rcv;
>> +	int i, ret, drops = n;
>>   	unsigned int max_len;
>>   	struct veth_rq *rq;
>> -	int i, drops = 0;
>>   
>> -	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
>> -		return -EINVAL;
>> +	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK)) {
>> +		ret = -EINVAL;
>> +		goto drop;
>> +	}
>>   
>>   	rcv = rcu_dereference(priv->peer);
>> -	if (unlikely(!rcv))
>> -		return -ENXIO;
>> +	if (unlikely(!rcv)) {
>> +		ret = -ENXIO;
>> +		goto drop;
>> +	}
>>   
>>   	rcv_priv = netdev_priv(rcv);
>>   	rq = &rcv_priv->rq[veth_select_rxq(rcv)];
>> @@ -325,9 +329,12 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
>>   	 * side. This means an XDP program is loaded on the peer and the peer
>>   	 * device is up.
>>   	 */
>> -	if (!rcu_access_pointer(rq->xdp_prog))
>> -		return -ENXIO;
>> +	if (!rcu_access_pointer(rq->xdp_prog)) {
>> +		ret = -ENXIO;
>> +		goto drop;
>> +	}
>>   
>> +	drops = 0;
>>   	max_len = rcv->mtu + rcv->hard_header_len + VLAN_HLEN;
>>   
>>   	spin_lock(&rq->xdp_ring.producer_lock);
>> @@ -346,7 +353,14 @@ static int veth_xdp_xmit(struct net_device *dev, int n,
>>   	if (flags & XDP_XMIT_FLUSH)
>>   		__veth_xdp_flush(rq);
>>   
>> -	return n - drops;
>> +	if (likely(!drops))
>> +		return n;
>> +
>> +	ret = n - drops;
>> +drop:
>> +	atomic64_add(drops, &priv->dropped);
>> +
>> +	return ret;
>>   }
>>   
>>   static void veth_xdp_flush(struct net_device *dev)

Re: [PATCH net-next 0/3] veth: XDP stats improvement

[David Miller]

From: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Date: Thu, 11 Oct 2018 18:36:47 +0900

> ndo_xdp_xmit in veth did not update packet counters as described in [1].
> Also, current implementation only updates counters on tx side so rx side
> events like XDP_DROP were not collected.
> This series implements the missing accounting as well as support for
> ethtool per-queue stats in veth.
> 
> Patch 1: Update drop counter in ndo_xdp_xmit.
> Patch 2: Update packet and byte counters for all XDP path, and drop
>          counter on XDP_DROP.
> Patch 3: Support per-queue ethtool stats for XDP counters.
> 
> Note that counters are maintained on per-queue basis for XDP but not
> otherwise (per-cpu and atomic as before). This is because 1) tx path in
> veth is essentially lockless so we cannot update per-queue stats on tx,
> and 2) rx path is net core routine (process_backlog) which cannot update
> per-queue based stats when XDP is disabled. On the other hand there are
> real rxqs and napi handlers for veth XDP, so update per-queue stats on
> rx for XDP packets, and use them to calculate tx counters as well,
> contrary to the existing non-XDP counters.
> 
> [1] https://patchwork.ozlabs.org/cover/953071/#1967449
> 
> Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>

Series applied.