From: Nick Bowler <nbowler@elliptictech.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Francois Romieu <romieu@fr.zoreil.com>,
netdev@vger.kernel.org,
Realtek linux nic maintainers <nic_swsd@realtek.com>
Subject: Re: Bogus frames transmitted with r8169 & fragmentation & large mtu
Date: Thu, 16 Feb 2012 11:14:42 -0500 [thread overview]
Message-ID: <20120216161442.GA10857@elliptictech.com> (raw)
In-Reply-To: <1329365963.2469.8.camel@edumazet-laptop>
On 2012-02-16 05:19 +0100, Eric Dumazet wrote:
> 1) Are you using SLUB, SLAB, or SLOB ?
SLUB.
> 2) Problem with MTU=9000 is that frames span several 4K pages.
>
> Maybe some versions of r8169 hardware have problems with that ...
Could be, but probably not the whole story. I tested some >4k MTU values
(all with 60K packets here because it failed more reliably than 30K).
6500 byte MTU appears to work OK (<1% loss). 7500 fails (>99% loss).
A largish range of MTU settings inbetween achieve a roughly 50% loss
rate.
The corruption is not always as significant as the original trace: some
of my tests had all the fragments correct but a mere two bytes of payload
were zero (resulting in the reassembled datagram being dropped due to a
checksum failure).
Recall that the original trace also had this "two bytes zeroed" problem
in the second fragment, in addition to all its other problems.
Cheers,
--
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
next prev parent reply other threads:[~2012-02-16 16:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-15 16:37 Bogus frames transmitted with r8169 & fragmentation & large mtu Nick Bowler
2012-02-15 19:13 ` Eric Dumazet
2012-02-15 19:58 ` Nick Bowler
2012-02-15 20:32 ` Nick Bowler
2012-02-15 23:23 ` Francois Romieu
2012-02-16 6:40 ` hayeswang
2012-02-16 7:46 ` Francois Romieu
2012-02-16 12:04 ` Francois Romieu
2012-02-21 2:58 ` hayeswang
2012-02-21 10:57 ` Francois Romieu
2012-02-15 22:41 ` Francois Romieu
2012-02-15 23:34 ` Nick Bowler
2012-02-16 4:19 ` Eric Dumazet
2012-02-16 16:14 ` Nick Bowler [this message]
2012-02-16 10:15 ` joeyli
2012-02-16 12:04 ` Francois Romieu
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