| Message ID | a7e1690c00c5dfe700c30eb9a8a81ec59f6545dd.1650884401.git.asml.silence@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 829b7bdd70449c211eb6b2673fcbc597ce120939 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next,1/1] tcp: optimise skb_zerocopy_iter_stream() | expand |
Hello: This patch was applied to netdev/net-next.git (master) by Jakub Kicinski <kuba@kernel.org>: On Thu, 28 Apr 2022 11:57:46 +0100 you wrote: > 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 <asml.silence@gmail.com> > --- > > [...] Here is the summary with links: - [net-next,1/1] tcp: optimise skb_zerocopy_iter_stream() https://git.kernel.org/netdev/net-next/c/829b7bdd7044 You are awesome, thank you!
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 30b523fa4ad2..e51e53f8c200 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1350,7 +1350,6 @@ 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 @@ -1364,7 +1363,7 @@ 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;
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 <asml.silence@gmail.com> --- split from a larger patchset, see https://lore.kernel.org/netdev/cover.1648981570.git.asml.silence@gmail.com/ net/core/skbuff.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)