[PATCH net-next] strparser: Call skb_unclone conditionally

[PATCH net-next] strparser: Call skb_unclone conditionally

[Vakul Garg]

Calling skb_unclone() is expensive as it triggers a memcpy operation.
Instead of calling skb_unclone() unconditionally, call it only when skb
has a shared frag_list. This improves tls rx throughout significantly.

Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Suggested-by: Boris Pismenny <borisp@mellanox.com>
---
 net/strparser/strparser.c | 26 +++++++++++++++-----------
 1 file changed, 15 insertions(+), 11 deletions(-)

diff --git a/net/strparser/strparser.c b/net/strparser/strparser.c
index 373836615c57..4f40a90ca016 100644
--- a/net/strparser/strparser.c
+++ b/net/strparser/strparser.c
@@ -155,11 +155,13 @@ static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
 			/* We are going to append to the frags_list of head.
 			 * Need to unshare the frag_list.
 			 */
-			err = skb_unclone(head, GFP_ATOMIC);
-			if (err) {
-				STRP_STATS_INCR(strp->stats.mem_fail);
-				desc->error = err;
-				return 0;
+			if (skb_has_frag_list(head)) {
+				err = skb_unclone(head, GFP_ATOMIC);
+				if (err) {
+					STRP_STATS_INCR(strp->stats.mem_fail);
+					desc->error = err;
+					return 0;
+				}
 			}
 
 			if (unlikely(skb_shinfo(head)->frag_list)) {
@@ -216,14 +218,16 @@ static int __strp_recv(read_descriptor_t *desc, struct sk_buff *orig_skb,
 			memset(stm, 0, sizeof(*stm));
 			stm->strp.offset = orig_offset + eaten;
 		} else {
-			/* Unclone since we may be appending to an skb that we
+			/* Unclone if we are appending to an skb that we
 			 * already share a frag_list with.
 			 */
-			err = skb_unclone(skb, GFP_ATOMIC);
-			if (err) {
-				STRP_STATS_INCR(strp->stats.mem_fail);
-				desc->error = err;
-				break;
+			if (skb_has_frag_list(skb)) {
+				err = skb_unclone(skb, GFP_ATOMIC);
+				if (err) {
+					STRP_STATS_INCR(strp->stats.mem_fail);
+					desc->error = err;
+					break;
+				}
 			}
 
 			stm = _strp_msg(head);
-- 
2.13.6

Re: [PATCH net-next] strparser: Call skb_unclone conditionally

[David Miller]

From: Vakul Garg <vakul.garg@nxp.com>
Date: Sat, 30 Jun 2018 00:45:55 +0530

> Calling skb_unclone() is expensive as it triggers a memcpy operation.
> Instead of calling skb_unclone() unconditionally, call it only when skb
> has a shared frag_list. This improves tls rx throughout significantly.
> 
> Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
> Suggested-by: Boris Pismenny <borisp@mellanox.com>

Applied.