From: Eric Dumazet <eric.dumazet@gmail.com>
To: Willy Tarreau <w@1wt.eu>
Cc: netdev@vger.kernel.org
Subject: Re: Stable regression with 'tcp: allow splice() to build full TSO packets'
Date: Fri, 18 May 2012 00:01:59 +0200 [thread overview]
Message-ID: <1337292119.3403.60.camel@edumazet-glaptop> (raw)
In-Reply-To: <1337291410.3403.52.camel@edumazet-glaptop>
On Thu, 2012-05-17 at 23:50 +0200, Eric Dumazet wrote:
> On Thu, 2012-05-17 at 23:40 +0200, Eric Dumazet wrote:
>
> > I dont understand why we should tcp_push() if we sent 0 bytes in this
> > splice() call.
> >
> > The push() should have be done already by prior splice() call, dont you
> > think ?
> >
> > out:
> > if (copied && !(flags & MSG_SENDPAGE_NOTLAST))
> > tcp_push(sk, flags, mss_now, tp->nonagle);
> >
>
> I think I now understand
>
> One splice() syscall actually calls do_tcp_sendpages() several times
> (N).
>
> Problem is N-1 calls are done with MSG_SENDPAGE_NOTLAST set
>
> And last one with MSG_SENDPAGE_NOTLAST unset
>
> So maybe we should replace this test by :
>
> if (!(flags & MSG_SENDPAGE_NOTLAST))
> tcp_push(...);
>
>
Its more tricky than that.
If we return 0 from do_tcp_sendpages(), __splice_from_pipe() wont call
us again, but we need to flush(). (This bug is indeed very old)
So maybe use :
if ((copied && !(flags & MSG_SENDPAGE_NOTLAST)) ||
!copied)
tcp_push(...);
next prev parent reply other threads:[~2012-05-17 22:02 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-17 12:18 Stable regression with 'tcp: allow splice() to build full TSO packets' Willy Tarreau
2012-05-17 15:01 ` Willy Tarreau
2012-05-17 15:43 ` Eric Dumazet
2012-05-17 15:56 ` Willy Tarreau
2012-05-17 16:33 ` Eric Dumazet
2012-05-17 16:40 ` Willy Tarreau
2012-05-17 16:47 ` Eric Dumazet
2012-05-17 16:49 ` Eric Dumazet
2012-05-17 17:22 ` Willy Tarreau
2012-05-17 17:34 ` [PATCH net-next] net: netdev_alloc_skb() use build_skb() Eric Dumazet
2012-05-17 17:45 ` Willy Tarreau
2012-06-04 12:39 ` Michael S. Tsirkin
2012-06-04 12:44 ` Willy Tarreau
2012-05-17 19:53 ` David Miller
2012-05-18 4:41 ` Eric Dumazet
2012-06-04 12:37 ` Michael S. Tsirkin
2012-06-04 13:06 ` Eric Dumazet
2012-06-04 13:41 ` Michael S. Tsirkin
2012-06-04 14:01 ` Eric Dumazet
2012-06-04 14:09 ` Eric Dumazet
2012-06-04 14:17 ` Michael S. Tsirkin
2012-06-04 15:01 ` Eric Dumazet
2012-06-04 17:20 ` Michael S. Tsirkin
2012-06-04 17:44 ` Eric Dumazet
2012-06-04 18:16 ` Michael S. Tsirkin
2012-06-04 19:24 ` Eric Dumazet
2012-06-04 19:48 ` Michael S. Tsirkin
2012-06-04 19:56 ` Eric Dumazet
2012-06-04 21:20 ` Michael S. Tsirkin
2012-06-05 2:50 ` Eric Dumazet
2012-06-04 18:16 ` Michael S. Tsirkin
2012-06-04 19:29 ` Eric Dumazet
2012-06-04 19:43 ` Michael S. Tsirkin
2012-06-04 19:52 ` Eric Dumazet
2012-06-04 21:54 ` Michael S. Tsirkin
2012-06-05 2:46 ` Eric Dumazet
2012-06-04 19:56 ` Michael S. Tsirkin
2012-06-04 20:05 ` Eric Dumazet
2012-05-17 18:38 ` Stable regression with 'tcp: allow splice() to build full TSO packets' Ben Hutchings
2012-05-17 19:55 ` David Miller
2012-05-17 20:04 ` Willy Tarreau
2012-05-17 20:07 ` David Miller
2012-05-17 20:41 ` Eric Dumazet
2012-05-17 21:14 ` Willy Tarreau
2012-05-17 21:40 ` Eric Dumazet
2012-05-17 21:50 ` Eric Dumazet
2012-05-17 21:57 ` Willy Tarreau
2012-05-17 22:01 ` Eric Dumazet [this message]
2012-05-17 22:10 ` Eric Dumazet
2012-05-17 22:16 ` Willy Tarreau
2012-05-17 22:22 ` Eric Dumazet
2012-05-17 22:24 ` Willy Tarreau
2012-05-17 22:25 ` David Miller
2012-05-17 22:30 ` Willy Tarreau
2012-05-17 22:35 ` David Miller
2012-05-17 22:49 ` Willy Tarreau
2012-05-17 22:27 ` Joe Perches
2012-05-17 21:54 ` Willy Tarreau
2012-05-17 21:47 ` Willy Tarreau
2012-05-17 22:14 ` Eric Dumazet
2012-05-17 22:29 ` Willy Tarreau
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