Commit 15070919 authored by Jesper Dangaard Brouer's avatar Jesper Dangaard Brouer Committed by David S. Miller
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mvneta: add XDP ethtool errors stats for TX to driver 



Adding ethtool stats for when XDP transmitted packets overrun the TX
queue. This is recorded separately for XDP_TX and ndo_xdp_xmit. This
is an important aid for troubleshooting XDP based setups.

It is currently a known weakness and property of XDP that there isn't
any push-back or congestion feedback when transmitting frames via XDP.
It's easy to realise when redirecting from a higher speed link into a
slower speed link, or simply two ingress links into a single egress.
The situation can also happen when Ethernet flow control is active.

For testing the patch and provoking the situation to occur on my
Espressobin board, I configured the TX-queue to be smaller (434) than
RX-queue (512) and overload network with large MTU size frames (as a
larger frame takes longer to transmit).

Hopefully the upcoming XDP TX hook can be extended to provide insight
into these TX queue overflows, to allow programmable adaptation
strategies.

Signed-off-by: default avatarJesper Dangaard Brouer <brouer@redhat.com>
Acked-by: default avatarLorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0b56a29f

drivers/net/ethernet/marvell/mvneta.c

+26 −4
Original line number Diff line number Diff line
@@ -344,8 +344,10 @@ enum { 
	ETHTOOL_XDP_REDIRECT,

	ETHTOOL_XDP_PASS,

	ETHTOOL_XDP_DROP,

	ETHTOOL_XDP_XMIT,

	ETHTOOL_XDP_TX,

	ETHTOOL_XDP_TX_ERR,

	ETHTOOL_XDP_XMIT,

	ETHTOOL_XDP_XMIT_ERR,

	ETHTOOL_MAX_STATS,

};
@@ -404,7 +406,9 @@ static const struct mvneta_statistic mvneta_statistics[] = { 
	{ ETHTOOL_XDP_PASS, T_SW, "rx_xdp_pass", },

	{ ETHTOOL_XDP_DROP, T_SW, "rx_xdp_drop", },

	{ ETHTOOL_XDP_TX, T_SW, "rx_xdp_tx", },

	{ ETHTOOL_XDP_TX_ERR, T_SW, "rx_xdp_tx_errors", },

	{ ETHTOOL_XDP_XMIT, T_SW, "tx_xdp_xmit", },

	{ ETHTOOL_XDP_XMIT_ERR, T_SW, "tx_xdp_xmit_errors", },

};



struct mvneta_stats {
@@ -417,7 +421,9 @@ struct mvneta_stats { 
	u64	xdp_pass;

	u64	xdp_drop;

	u64	xdp_xmit;

	u64	xdp_xmit_err;

	u64	xdp_tx;

	u64	xdp_tx_err;

};



struct mvneta_ethtool_stats {
@@ -2059,6 +2065,7 @@ mvneta_xdp_submit_frame(struct mvneta_port *pp, struct mvneta_tx_queue *txq, 
static int

mvneta_xdp_xmit_back(struct mvneta_port *pp, struct xdp_buff *xdp)

{

	struct mvneta_pcpu_stats *stats = this_cpu_ptr(pp->stats);

	struct mvneta_tx_queue *txq;

	struct netdev_queue *nq;

	struct xdp_frame *xdpf;
@@ -2076,8 +2083,6 @@ mvneta_xdp_xmit_back(struct mvneta_port *pp, struct xdp_buff *xdp) 
	__netif_tx_lock(nq, cpu);

	ret = mvneta_xdp_submit_frame(pp, txq, xdpf, false);

	if (ret == MVNETA_XDP_TX) {

		struct mvneta_pcpu_stats *stats = this_cpu_ptr(pp->stats);



		u64_stats_update_begin(&stats->syncp);

		stats->es.ps.tx_bytes += xdpf->len;

		stats->es.ps.tx_packets++;
@@ -2085,6 +2090,10 @@ mvneta_xdp_xmit_back(struct mvneta_port *pp, struct xdp_buff *xdp) 
		u64_stats_update_end(&stats->syncp);



		mvneta_txq_pend_desc_add(pp, txq, 0);

	} else {

		u64_stats_update_begin(&stats->syncp);

		stats->es.ps.xdp_tx_err++;

		u64_stats_update_end(&stats->syncp);

	}

	__netif_tx_unlock(nq);
@@ -2128,6 +2137,7 @@ mvneta_xdp_xmit(struct net_device *dev, int num_frame, 
	stats->es.ps.tx_bytes += nxmit_byte;

	stats->es.ps.tx_packets += nxmit;

	stats->es.ps.xdp_xmit += nxmit;

	stats->es.ps.xdp_xmit_err += num_frame - nxmit;

	u64_stats_update_end(&stats->syncp);



	return nxmit;
@@ -2152,7 +2162,7 @@ mvneta_run_xdp(struct mvneta_port *pp, struct mvneta_rx_queue *rxq, 
		int err;



		err = xdp_do_redirect(pp->dev, xdp, prog);

		if (err) {

		if (unlikely(err)) {

			ret = MVNETA_XDP_DROPPED;

			page_pool_put_page(rxq->page_pool,

					   virt_to_head_page(xdp->data), len,
@@ -4518,6 +4528,8 @@ mvneta_ethtool_update_pcpu_stats(struct mvneta_port *pp, 
		u64 skb_alloc_error;

		u64 refill_error;

		u64 xdp_redirect;

		u64 xdp_xmit_err;

		u64 xdp_tx_err;

		u64 xdp_pass;

		u64 xdp_drop;

		u64 xdp_xmit;
@@ -4532,7 +4544,9 @@ mvneta_ethtool_update_pcpu_stats(struct mvneta_port *pp, 
			xdp_pass = stats->es.ps.xdp_pass;

			xdp_drop = stats->es.ps.xdp_drop;

			xdp_xmit = stats->es.ps.xdp_xmit;

			xdp_xmit_err = stats->es.ps.xdp_xmit_err;

			xdp_tx = stats->es.ps.xdp_tx;

			xdp_tx_err = stats->es.ps.xdp_tx_err;

		} while (u64_stats_fetch_retry_irq(&stats->syncp, start));



		es->skb_alloc_error += skb_alloc_error;
@@ -4541,7 +4555,9 @@ mvneta_ethtool_update_pcpu_stats(struct mvneta_port *pp, 
		es->ps.xdp_pass += xdp_pass;

		es->ps.xdp_drop += xdp_drop;

		es->ps.xdp_xmit += xdp_xmit;

		es->ps.xdp_xmit_err += xdp_xmit_err;

		es->ps.xdp_tx += xdp_tx;

		es->ps.xdp_tx_err += xdp_tx_err;

	}

}
@@ -4594,9 +4610,15 @@ static void mvneta_ethtool_update_stats(struct mvneta_port *pp) 
			case ETHTOOL_XDP_TX:

				pp->ethtool_stats[i] = stats.ps.xdp_tx;

				break;

			case ETHTOOL_XDP_TX_ERR:

				pp->ethtool_stats[i] = stats.ps.xdp_tx_err;

				break;

			case ETHTOOL_XDP_XMIT:

				pp->ethtool_stats[i] = stats.ps.xdp_xmit;

				break;

			case ETHTOOL_XDP_XMIT_ERR:

				pp->ethtool_stats[i] = stats.ps.xdp_xmit_err;

				break;

			}

			break;

		}

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