Re: Major network performance regression in 3.7

Eric Dumazet
2013-01-06T17:10:57Z

On Sun, 2013-01-06 at 17:44 +0100, Willy Tarreau wrote:
> On Sun, Jan 06, 2013 at 08:39:53AM -0800, Eric Dumazet wrote:
> > Hmm, I'll have to check if this really can be reverted without hurting
> > vmsplice() again.
>
> Looking at the code I've been wondering whether we shouldn't transform
> the condition to perform the push if we can't push more segments, but
> I don't know what to rely on. It would be something like this :
>
> if (copied &&
> (!(flags & MSG_SENDPAGE_NOTLAST) || cant_push_more))
> tcp_push(sk, flags, mss_now, tp->nonagle);

Good point !

Maybe the following fix then ?

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 1ca2536..7ba0717 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -941,8 +941,10 @@ out:
return copied;

do_error:
- if (copied)
+ if (copied) {
+ flags &= ~MSG_SENDPAGE_NOTLAST;
goto out;
+ }
out_err:
return sk_stream_error(sk, flags, err);
}