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 <zoltan.kiss@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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)
