DSA needs to push a header onto every packet on TX, and this might cause
reallocation under certain scenarios, which might affect, for example,
performance.
But reallocated packets are not standardized in struct pcpu_sw_netstats,
struct net_device_stats or anywhere else, it seems, so we need to roll
our own extra netdevice statistics and expose them to ethtool.
Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com>
---
net/dsa/dsa_priv.h | 9 +++++++++
net/dsa/slave.c | 25 ++++++++++++++++++++++---
2 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index 12998bf04e55..d39db7500cdd 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -73,12 +73,21 @@ struct dsa_notifier_mtu_info {
int mtu;
};
+/* Driver statistics, other than those in struct rtnl_link_stats64.
+ * These are collected per-CPU and aggregated by ethtool.
+ */
+struct dsa_slave_stats {
+ __u64 tx_reallocs;
+ struct u64_stats_sync syncp;
+} __aligned(1 * sizeof(u64));
+
struct dsa_slave_priv {
/* Copy of CPU port xmit for faster access in slave transmit hot path */
struct sk_buff * (*xmit)(struct sk_buff *skb,
struct net_device *dev);
struct pcpu_sw_netstats __percpu *stats64;
+ struct dsa_slave_stats __percpu *extra_stats;
struct gro_cells gcells;
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 3bc5ca40c9fb..d4326940233c 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -668,9 +668,10 @@ static void dsa_slave_get_strings(struct net_device *dev,
strncpy(data + len, "tx_bytes", len);
strncpy(data + 2 * len, "rx_packets", len);
strncpy(data + 3 * len, "rx_bytes", len);
+ strncpy(data + 4 * len, "tx_reallocs", len);
if (ds->ops->get_strings)
ds->ops->get_strings(ds, dp->index, stringset,
- data + 4 * len);
+ data + 5 * len);
}
}
@@ -682,11 +683,13 @@ static void dsa_slave_get_ethtool_stats(struct net_device
*dev,
struct dsa_slave_priv *p = netdev_priv(dev);
struct dsa_switch *ds = dp->ds;
struct pcpu_sw_netstats *s;
+ struct dsa_slave_stats *e;
unsigned int start;
int i;
for_each_possible_cpu(i) {
u64 tx_packets, tx_bytes, rx_packets, rx_bytes;
+ u64 tx_reallocs;
s = per_cpu_ptr(p->stats64, i);
do {
@@ -696,13 +699,21 @@ static void dsa_slave_get_ethtool_stats(struct net_device
*dev,
rx_packets = s->rx_packets;
rx_bytes = s->rx_bytes;
} while (u64_stats_fetch_retry_irq(&s->syncp, start));
+
+ e = per_cpu_ptr(p->extra_stats, i);
+ do {
+ start = u64_stats_fetch_begin_irq(&e->syncp);
+ tx_reallocs = e->tx_reallocs;
+ } while (u64_stats_fetch_retry_irq(&e->syncp, start));
+
data[0] += tx_packets;
data[1] += tx_bytes;
data[2] += rx_packets;
data[3] += rx_bytes;
+ data[4] += tx_reallocs;
}
if (ds->ops->get_ethtool_stats)
- ds->ops->get_ethtool_stats(ds, dp->index, data + 4);
+ ds->ops->get_ethtool_stats(ds, dp->index, data + 5);
}
static int dsa_slave_get_sset_count(struct net_device *dev, int sset)
@@ -713,7 +724,7 @@ static int dsa_slave_get_sset_count(struct net_device *dev,
int sset)
if (sset == ETH_SS_STATS) {
int count;
- count = 4;
+ count = 5;
if (ds->ops->get_sset_count)
count += ds->ops->get_sset_count(ds, dp->index, sset);
@@ -1806,6 +1817,12 @@ int dsa_slave_create(struct dsa_port *port)
free_netdev(slave_dev);
return -ENOMEM;
}
+ p->extra_stats = netdev_alloc_pcpu_stats(struct dsa_slave_stats);
+ if (!p->extra_stats) {
+ free_percpu(p->stats64);
+ free_netdev(slave_dev);
+ return -ENOMEM;
+ }
ret = gro_cells_init(&p->gcells, slave_dev);
if (ret)
@@ -1864,6 +1881,7 @@ int dsa_slave_create(struct dsa_port *port)
out_gcells:
gro_cells_destroy(&p->gcells);
out_free:
+ free_percpu(p->extra_stats);
free_percpu(p->stats64);
free_netdev(slave_dev);
port->slave = NULL;
@@ -1886,6 +1904,7 @@ void dsa_slave_destroy(struct net_device *slave_dev)
dsa_slave_notify(slave_dev, DSA_PORT_UNREGISTER);
phylink_destroy(dp->pl);
gro_cells_destroy(&p->gcells);
+ free_percpu(p->extra_stats);
free_percpu(p->stats64);
free_netdev(slave_dev);
}
--
2.25.1
