netdev - Re: Reproducible data corruption with sendfile+vsftp

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Message-ID: <20071206184426.GA32599@electric-eye.fr.zoreil.com>
Date:	Thu, 6 Dec 2007 19:44:26 +0100
From:	Francois Romieu <romieu@...zoreil.com>
To:	Holger Hoffstaette <holger@...ards.de>
Cc:	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	torvalds@...ux-foundation.org
Subject: Re: Reproducible data corruption with sendfile+vsftp - splice
	regression?

Holger Hoffstaette <holger@...ards.de> :
[...]
> Maybe turning off sendfile or NAPI just lead to random success - so far it
> really looks like tso on the r8169 is the common cause.

TSO on the r8169 is the magic switch but the regression makes imvho more
sense from a VM pov:

- the corrupted file has the same size as the expected file
- the corrupted file exhibits holes which come as a multiple of 4096 bytes
  (8*4k, 2 places, there may be more)
- the r8169 driver does not know what a page is
- the 8169 hardware has a small 8192 bytes Tx buffer

It would be nice if someone could do a sendfile + vsftp test with TSO on a
different hardware. While I could not reproduce the corruption when simply
downloading a file that I had copied on the server with scp, it triggered
almost immediately after I copied it locally and tried to download the copy.

-- 
Ueimor
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