netdev - Re: [PATCH][RFC] network splice receive

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Message-ID: <20070605122031.GE9909@kernel.dk>
Date:	Tue, 5 Jun 2007 14:20:31 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	netdev@...r.kernel.org
Subject: Re: [PATCH][RFC] network splice receive

On Tue, Jun 05 2007, Jens Axboe wrote:
> On Tue, Jun 05 2007, Jens Axboe wrote:
> > Seems to work reasonably well for me, sometimes I do see small ranges
> > inside the output file that are not correct, but I haven't been able to
> > reproduce today. I think it has to do with page reuse, hence the
> > NET_COPY_SPLICE ifdef that you can enable to just plain copy the data
> > instead of referencing it.
> 
> I managed to reproduce. It's segments of 68-80 bytes beyond corrupt in
> the middle of the out, and there might be 1-3 of such occurences in the
> 30mb file I tested with. The first 16 bytes of the corruption are always
> the same:
> 
> 0000 1800 4ff3 937f e000 6381 7275 0008
> 
> Perhaps that hex pattern rings a bell with someone intimate with the
> networking. The remaining wrong bytes don't seem to have anything in
> common.

Ok, the source mac address is 00:18:F3:4F:7F:93 and the destination is
00:E0:81:63:75:72 which are the middle 12 bytes of the 16.

Hope that helps someone clue me in as to which network part is reusing
the data. Do I need to 'pin' the sk_buff until the pipe data has been
consumed?

-- 
Jens Axboe

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