netdev - Re: [Bugme-new] [Bug 38102] New: BUG kmalloc-2048: Poison overwritten

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Message-ID: <CAB9v_DGSFAG9V0jqem+tDP3G-N8v6Z+_6oKdPwL-ZwhfhCOZnw@mail.gmail.com>
Date:	Tue, 5 Jul 2011 08:17:37 +0400
From:	Alexey Zaytsev <alexey.zaytsev@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Michael Büsch <m@...s.ch>,
	Andrew Morton <akpm@...ux-foundation.org>,
	netdev@...r.kernel.org, Gary Zambrano <zambrano@...adcom.com>,
	bugme-daemon@...zilla.kernel.org,
	"David S. Miller" <davem@...emloft.net>,
	Pekka Pietikainen <pp@...oulu.fi>,
	Florian Schirmer <jolt@...box.org>,
	Felix Fietkau <nbd@...nwrt.org>, Michael Buesch <mb@...sch.de>
Subject: Re: [Bugme-new] [Bug 38102] New: BUG kmalloc-2048: Poison overwritten

On Tue, Jul 5, 2011 at 08:14, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le mardi 05 juillet 2011 à 06:11 +0200, Eric Dumazet a écrit :
>> Le mardi 05 juillet 2011 à 07:56 +0400, Alexey Zaytsev a écrit :
>> > On Tue, Jul 5, 2011 at 07:44, Eric Dumazet <eric.dumazet@...il.com> wrote:
>> > >
>> > > I dont care about duplicate acks at this point.
>> > >
>> > > Thats a separate issue (TCP layer)
>> > >
>> >
>> > Maybe some tx packets are just sent out more then once? Or a single
>> > packet is sent out instead of some other packets?
>> > The delays between two dups is short, and they come in bursts, up to a
>> > few hundreds of duplicate packets at a time.
>> >
>>
>> Thats a completely different problem. SSH is very expensive for your
>> receiver (your dump1 file has small packets (560 bytes)), and it cannot
>> cope with the stress.
>>
>> You're filling the b44 rx ring, and b44 driver has no choice to zap 200
>> packets at once. This sure is a problem for tcp, as it stalls the thing.
>>
>> You could avoid this by doing this at b44 machine (the receiver)
>>
>> echo "4096 32768 87380" >/proc/sys/net/ipv4/tcp_rmem
>>
>> So that sender wont be able to push so many packets
>
> You can also try using more packets in rx ring : (default is 200
> packets, limit ~511)
>
> ethtool -G eth0 rx 400
>
>
Check out starting at packet 302893. 383 _identical_ ACKs were sent
out by the b44 machine within 30 milliseconds.

>
>
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