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From: Willy Tarreau <w@1wt.eu>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: netdev@vger.kernel.org
Subject: Re: Stable regression with 'tcp: allow splice() to build full TSO packets'
Date: Thu, 17 May 2012 23:57:59 +0200	[thread overview]
Message-ID: <20120517215759.GR14498@1wt.eu> (raw)
In-Reply-To: <1337291410.3403.52.camel@edumazet-glaptop>

On Thu, May 17, 2012 at 11:50:10PM +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(...);

Just tested, and it unfortunately does not fix the issue :-(

I'll see if I can log errors from lower layers.
Willy

  reply	other threads:[~2012-05-17 21:58 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 [this message]
2012-05-17 22:01         ` Eric Dumazet
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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