From 829b7bdd70449c211eb6b2673fcbc597ce120939 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Thu, 28 Apr 2022 11:57:46 +0100 Subject: tcp: optimise skb_zerocopy_iter_stream() It's expensive to make a copy of 40B struct iov_iter to the point it was taking 0.2-0.5% of all cycles in my tests. iov_iter_revert() should be fine as it's a simple case without nested reverts/truncates. Signed-off-by: Pavel Begunkov Link: https://lore.kernel.org/r/a7e1690c00c5dfe700c30eb9a8a81ec59f6545dd.1650884401.git.asml.silence@gmail.com Signed-off-by: Jakub Kicinski --- net/core/skbuff.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'net/core') diff --git a/net/core/skbuff.c b/net/core/skbuff.c index b92e93dcaa91..475183f37891 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1344,7 +1344,6 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb, struct ubuf_info *uarg) { struct ubuf_info *orig_uarg = skb_zcopy(skb); - struct iov_iter orig_iter = msg->msg_iter; int err, orig_len = skb->len; /* An skb can only point to one uarg. This edge case happens when @@ -1358,7 +1357,7 @@ int skb_zerocopy_iter_stream(struct sock *sk, struct sk_buff *skb, struct sock *save_sk = skb->sk; /* Streams do not free skb on error. Reset to prev state. */ - msg->msg_iter = orig_iter; + iov_iter_revert(&msg->msg_iter, skb->len - orig_len); skb->sk = sk; ___pskb_trim(skb, orig_len); skb->sk = save_sk; -- cgit v1.2.3