[35/49] net: release dst entry while cache-hot for GSO case too

From: Greg KH
Date: Wed Jan 05 2011 - 18:48:35 EST


2.6.32-longterm review patch. If anyone has any objections, please let us know.

------------------

From: Krishna Kumar <krkumar2@xxxxxxxxxx>

commit 068a2de57ddf4f472e32e7af868613c574ad1d88 upstream.

Non-GSO code drops dst entry for performance reasons, but
the same is missing for GSO code. Drop dst while cache-hot
for GSO case too.

Signed-off-by: Krishna Kumar <krkumar2@xxxxxxxxxx>
Acked-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Andrey Vagin <avagin@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
net/core/dev.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1747,6 +1747,14 @@ gso:

skb->next = nskb->next;
nskb->next = NULL;
+
+ /*
+ * If device doesnt need nskb->dst, release it right now while
+ * its hot in this cpu cache
+ */
+ if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
+ skb_dst_drop(nskb);
+
rc = ops->ndo_start_xmit(nskb, dev);
if (unlikely(rc != NETDEV_TX_OK)) {
nskb->next = skb->next;


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