From: David Miller <davem@davemloft.net>
To: rusty@rustcorp.com.au
Cc: herbert@gondor.apana.org.au, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org,
virtualization@lists.linux-foundation.org, maxk@qualcomm.com
Subject: Re: [PATCH RFC 4/5] tun: vringfd xmit support.
Date: Mon, 07 Apr 2008 00:35:28 -0700 (PDT) [thread overview]
Message-ID: <20080407.003528.96136816.davem@davemloft.net> (raw)
In-Reply-To: <200804071724.51781.rusty@rustcorp.com.au>
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 7 Apr 2008 17:24:51 +1000
> On Monday 07 April 2008 15:13:44 Herbert Xu wrote:
> > On second thought, this is not going to work. The network stack
> > can clone individual pages out of this skb and put it into a new
> > skb. Therefore whatever scheme we come up with will either need
> > to be page-based, or add a flag to tell the network stack that it
> > can't clone those pages.
>
> Erk... I'll put in the latter for now. A page-level solution is not really
> an option: if userspace hands us mmaped pages for example.
Keep in mind that the core of the TCP stack really depends
upon being able to slice and dice paged SKBs as is pleases
in order to send packets out.
In fact, it also does such splitting during SACK processing.
It really is a base requirement for efficient TSO support.
Otherwise the above operations would be so incredibly
expensive we might as well rip all of the TSO support out.
next prev parent reply other threads:[~2008-04-07 7:35 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-04-05 12:02 [PATCH RFC 1/5] vringfd syscall Rusty Russell
2008-04-05 12:04 ` [PATCH RFC 2/5] vringfd base/offset Rusty Russell
2008-04-05 12:05 ` [PATCH RFC 3/5] tun: vringfd receive support Rusty Russell
2008-04-05 12:06 ` [PATCH RFC 4/5] tun: vringfd xmit support Rusty Russell
2008-04-05 12:09 ` [PATCH RFC 5/5] lguest support Rusty Russell
2008-04-07 5:13 ` [PATCH RFC 4/5] tun: vringfd xmit support Herbert Xu
2008-04-07 7:24 ` Rusty Russell
2008-04-07 7:35 ` David Miller [this message]
2008-04-08 1:51 ` Rusty Russell
2008-04-08 19:49 ` [PATCH RFC 3/5] tun: vringfd receive support Max Krasnyansky
2008-04-09 12:46 ` Dor Laor
2008-04-10 17:02 ` Max Krasnyanskiy
2008-04-10 5:44 ` Rusty Russell
2008-04-10 17:18 ` Max Krasnyanskiy
2008-04-05 12:44 ` [PATCH RFC 2/5] vringfd base/offset Avi Kivity
2008-04-06 2:54 ` Rusty Russell
[not found] ` <200804052205.43824.rusty__2650.41595926068$1207397436$gmane$org@rustcorp.com.au>
2008-04-05 17:26 ` [PATCH RFC 3/5] tun: vringfd receive support Anthony Liguori
2008-04-08 5:14 ` [PATCH RFC 2/5] vringfd base/offset Arnd Bergmann
[not found] ` <200804052204.28518.rusty__10896.9346424148$1207397431$gmane$org@rustcorp.com.au>
2008-04-05 17:18 ` Anthony Liguori
2008-04-06 3:23 ` Rusty Russell
2008-04-07 17:54 ` [PATCH RFC 1/5] vringfd syscall Jonathan Corbet
2008-04-07 22:34 ` Rusty Russell
2008-04-08 2:35 ` Arnd Bergmann
2008-04-09 19:28 ` Jeremy Fitzhardinge
2008-04-12 17:18 ` Marcelo Tosatti
2008-04-12 17:39 ` Marcelo Tosatti
2008-04-12 18:19 ` Rusty Russell
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