net: mvneta: increase the 64-bit rx/tx stats out of the hot path

commit dc4277dd41a80fd5f29a90412ea04bc3ba54fbf1 upstream.

Better count packets and bytes in the stack and on 32 bit then
accumulate them at the end for once. This saves two memory writes
and two memory barriers per packet. The incoming packet rate was
increased by 4.7% on the Openblocks AX3 thanks to this.

Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gregory CLEMENT <gregory.clement@free-electrons.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Tested-by: Arnaud Ebalard <arno@natisbad.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c
index 658613021919477981150d542527c1e936fa6ad2..0c0b5763549a068e24180d88b6626291cbf5e3d2 100644 (file)
--- a/drivers/net/ethernet/marvell/mvneta.c
+++ b/drivers/net/ethernet/marvell/mvneta.c
@@ -1354,6 +1354,8 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 {
        struct net_device *dev = pp->dev;
        int rx_done, rx_filled;
+       u32 rcvd_pkts = 0;
+       u32 rcvd_bytes = 0;
 
        /* Get number of received packets */
        rx_done = mvneta_rxq_busy_desc_num_get(pp, rxq);
@@ -1391,10 +1393,8 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
 
                rx_bytes = rx_desc->data_size -
                        (ETH_FCS_LEN + MVNETA_MH_SIZE);
-               u64_stats_update_begin(&pp->rx_stats.syncp);
-               pp->rx_stats.packets++;
-               pp->rx_stats.bytes += rx_bytes;
-               u64_stats_update_end(&pp->rx_stats.syncp);
+               rcvd_pkts++;
+               rcvd_bytes += rx_bytes;
 
                /* Linux processing */
                skb_reserve(skb, MVNETA_MH_SIZE);
@@ -1415,6 +1415,13 @@ static int mvneta_rx(struct mvneta_port *pp, int rx_todo,
                }
        }
 
+       if (rcvd_pkts) {
+               u64_stats_update_begin(&pp->rx_stats.syncp);
+               pp->rx_stats.packets += rcvd_pkts;
+               pp->rx_stats.bytes   += rcvd_bytes;
+               u64_stats_update_end(&pp->rx_stats.syncp);
+       }
+
        /* Update rxq management counters */
        mvneta_rxq_desc_num_update(pp, rxq, rx_done, rx_filled);