[NET]: reduce per cpu ram used for loopback stats
We dont need a full struct net_device_stats (currently 23 long : 184 bytes on
x86_64) per possible CPU, but only two counters : bytes and packets
We save few CPU cycles too in loopback_xmit() not updating 4 fields, but 2.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index 4178b4b1..93fbea1 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -58,7 +58,11 @@
#include <linux/tcp.h>
#include <linux/percpu.h>
-static DEFINE_PER_CPU(struct net_device_stats, loopback_stats);
+struct pcpu_lstats {
+ unsigned long packets;
+ unsigned long bytes;
+};
+static DEFINE_PER_CPU(struct pcpu_lstats, pcpu_lstats);
#define LOOPBACK_OVERHEAD (128 + MAX_HEADER + 16 + 16)
@@ -128,7 +132,7 @@
*/
static int loopback_xmit(struct sk_buff *skb, struct net_device *dev)
{
- struct net_device_stats *lb_stats;
+ struct pcpu_lstats *lb_stats;
skb_orphan(skb);
@@ -149,11 +153,9 @@
#endif
dev->last_rx = jiffies;
- lb_stats = &per_cpu(loopback_stats, get_cpu());
- lb_stats->rx_bytes += skb->len;
- lb_stats->tx_bytes = lb_stats->rx_bytes;
- lb_stats->rx_packets++;
- lb_stats->tx_packets = lb_stats->rx_packets;
+ lb_stats = &per_cpu(pcpu_lstats, get_cpu());
+ lb_stats->bytes += skb->len;
+ lb_stats->packets++;
put_cpu();
netif_rx(skb);
@@ -166,20 +168,21 @@
static struct net_device_stats *get_stats(struct net_device *dev)
{
struct net_device_stats *stats = &loopback_stats;
+ unsigned long bytes = 0;
+ unsigned long packets = 0;
int i;
- memset(stats, 0, sizeof(struct net_device_stats));
-
for_each_possible_cpu(i) {
- struct net_device_stats *lb_stats;
+ const struct pcpu_lstats *lb_stats;
- lb_stats = &per_cpu(loopback_stats, i);
- stats->rx_bytes += lb_stats->rx_bytes;
- stats->tx_bytes += lb_stats->tx_bytes;
- stats->rx_packets += lb_stats->rx_packets;
- stats->tx_packets += lb_stats->tx_packets;
+ lb_stats = &per_cpu(pcpu_lstats, i);
+ bytes += lb_stats->bytes;
+ packets += lb_stats->packets;
}
-
+ stats->rx_packets = packets;
+ stats->tx_packets = packets;
+ stats->rx_bytes = bytes;
+ stats->tx_bytes = bytes;
return stats;
}