linux-kernel - Re: Reproducible data corruption with sendfile+vsftp

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Date:	Sat, 15 Dec 2007 14:43:18 +0100
From:	"Holger Hoffstaette" <holger@...ards.de>
To:	linux-kernel@...r.kernel.org
Cc:	netdev@...r.kernel.org
Subject:  Re: Reproducible data corruption with sendfile+vsftp - splice regression?

On Thu, 06 Dec 2007 19:44:26 +0100, Francois Romieu wrote:

> 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.

I tested 2.6.24-rc5 on my T60 (Intel e1000 built with NAPI) and installed
vsftp/apache with sendfile and enabled all offload options incl. TSO.
Repeated downloads of >500 MB with ftp or wget over the NIC onto ram- or
physical disk gives no corruption whatsoever. Speed of download to ramdisk
is a nice continuous 125 MB/sec.
Looks like the r8169 or the driver after all..

thanks
Holger

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