* [PATCH net-next 1/1] tcp: optimise skb_zerocopy_iter_stream()
@ 2022-04-28 10:57 Pavel Begunkov
2022-05-02 21:50 ` patchwork-bot+netdevbpf
0 siblings, 1 reply; 2+ messages in thread
From: Pavel Begunkov @ 2022-04-28 10:57 UTC (permalink / raw)
To: netdev, David S . Miller, Jakub Kicinski
Cc: David Ahern, Eric Dumazet, Willem de Bruijn, linux-kernel,
Pavel Begunkov
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(-)
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;
--
2.36.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net-next 1/1] tcp: optimise skb_zerocopy_iter_stream()
2022-04-28 10:57 [PATCH net-next 1/1] tcp: optimise skb_zerocopy_iter_stream() Pavel Begunkov
@ 2022-05-02 21:50 ` patchwork-bot+netdevbpf
0 siblings, 0 replies; 2+ messages in thread
From: patchwork-bot+netdevbpf @ 2022-05-02 21:50 UTC (permalink / raw)
To: Pavel Begunkov
Cc: netdev, davem, kuba, dsahern, edumazet, willemdebruijn.kernel,
linux-kernel
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!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 2+ messages in thread
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2022-04-28 10:57 [PATCH net-next 1/1] tcp: optimise skb_zerocopy_iter_stream() Pavel Begunkov
2022-05-02 21:50 ` patchwork-bot+netdevbpf
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