xen-netback: Add stat counters for zerocopy
These counters help determine how often the buffers had to be copied. Also
they help find out if packets are leaked, as if "sent != success + fail",
there are probably packets never freed up properly.
NOTE: if bisect brought you here, you should apply the series up until
"xen-netback: Timeout packets in RX path", otherwise Windows guests can't work
properly and malicious guests can block other guests by not releasing their sent
packets.
Signed-off-by: Zoltan Kiss <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/drivers/net/xen-netback/common.h b/drivers/net/xen-netback/common.h
index 49109afa..683d301 100644
--- a/drivers/net/xen-netback/common.h
+++ b/drivers/net/xen-netback/common.h
@@ -179,6 +179,9 @@
/* Statistics */
unsigned long rx_gso_checksum_fixup;
+ unsigned long tx_zerocopy_sent;
+ unsigned long tx_zerocopy_success;
+ unsigned long tx_zerocopy_fail;
/* Miscellaneous private stuff. */
struct net_device *dev;
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 1fe9fe5..44df858 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -238,6 +238,21 @@
"rx_gso_checksum_fixup",
offsetof(struct xenvif, rx_gso_checksum_fixup)
},
+ /* If (sent != success + fail), there are probably packets never
+ * freed up properly!
+ */
+ {
+ "tx_zerocopy_sent",
+ offsetof(struct xenvif, tx_zerocopy_sent),
+ },
+ {
+ "tx_zerocopy_success",
+ offsetof(struct xenvif, tx_zerocopy_success),
+ },
+ {
+ "tx_zerocopy_fail",
+ offsetof(struct xenvif, tx_zerocopy_fail)
+ },
};
static int xenvif_get_sset_count(struct net_device *dev, int string_set)
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 46a7570..3cb5863 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -1323,8 +1323,10 @@
* do a skb_copy_ubufs while we are still in control of the
* skb. E.g. the __pskb_pull_tail earlier can do such thing.
*/
- if (skb_shinfo(skb)->destructor_arg)
+ if (skb_shinfo(skb)->destructor_arg) {
skb_shinfo(skb)->tx_flags |= SKBTX_DEV_ZEROCOPY;
+ vif->tx_zerocopy_sent++;
+ }
netif_receive_skb(skb);
}
@@ -1364,6 +1366,11 @@
napi_schedule(&vif->napi);
local_bh_enable();
}
+
+ if (likely(zerocopy_success))
+ vif->tx_zerocopy_success++;
+ else
+ vif->tx_zerocopy_fail++;
}
static inline void xenvif_tx_dealloc_action(struct xenvif *vif)
