From: TB <lkml@techboom•com>
To: Stephen Hemminger <shemminger@vyatta•com>
Cc: "Brandeburg, Jesse" <jesse.brandeburg@intel•com>,
David Miller <davem@davemloft•net>,
Sangtae Ha <sangtae.ha@gmail•com>,
Injong Rhee <injongrhee@gmail•com>,
"Valdis.Kletnieks@vt•edu" <Valdis.Kletnieks@vt•edu>,
"rdunlap@xenotime•net" <rdunlap@xenotime•net>,
"netdev@vger•kernel.org" <netdev@vger•kernel.org>,
"linux-kernel@vger•kernel.org" <linux-kernel@vger•kernel.org>
Subject: Re: [PATCH] tcp_cubic: limit delayed_ack ratio to prevent divide error
Date: Fri, 06 May 2011 13:39:53 -0400 [thread overview]
Message-ID: <4DC43269.9040503@techboom.com> (raw)
In-Reply-To: <20110506095359.57c4fb38@nehalam>
On 11-05-06 12:53 PM, Stephen Hemminger wrote:
> On Fri, 06 May 2011 12:15:46 -0400
> TB <lkml@techboom•com> wrote:
>
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> On 11-05-04 04:53 PM, Brandeburg, Jesse wrote:
>>>
>>>
>>> On Wed, 4 May 2011, Stephen Hemminger wrote:
>>>
>>>> TCP Cubic keeps a metric that estimates the amount of delayed
>>>> acknowledgements to use in adjusting the window. If an abnormally
>>>> large number of packets are acknowledged at once, then the update
>>>> could wrap and reach zero. This kind of ACK could only
>>>> happen when there was a large window and huge number of
>>>> ACK's were lost.
>>>>
>>>> This patch limits the value of delayed ack ratio. The choice of 32
>>>> is just a conservative value since normally it should be range of
>>>> 1 to 4 packets.
>>>>
>>>> Signed-off-by: Stephen Hemminger <shemminger@vyatta•com>
>>>
>>> patch seems fine, but please credit the reporter (lkml@techboom•com) with
>>> reporting the issue with logs, maybe even with Reported-by: and some kind
>>> of reference to the panic message or the email thread in the text or
>>> header?
>>
>> We're currently testing the patch on 6 production servers
>
> Thank you, is there some regularity to the failures previously?
Not really, there was more chance of it happening after a reboot and
during the night (when there is less traffic) for some weird reason.
As a workaround we switched most of the servers to reno
next prev parent reply other threads:[~2011-05-06 17:39 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <4DC178D3.6030308@techboom.com>
2011-05-04 17:49 ` Divide error in bictcp_cong_avoid ? Randy Dunlap
2011-05-04 18:33 ` Stephen Hemminger
2011-05-04 18:35 ` Randy Dunlap
2011-05-04 19:03 ` TB
2011-05-04 18:56 ` David Miller
2011-05-04 19:31 ` Valdis.Kletnieks
2011-05-04 19:37 ` Stephen Hemminger
2011-05-04 19:40 ` David Miller
2011-05-04 20:01 ` Valdis.Kletnieks
2011-05-04 20:04 ` [PATCH] tcp_cubic: limit delayed_ack ratio to prevent divide error Stephen Hemminger
2011-05-04 20:53 ` Brandeburg, Jesse
2011-05-06 16:15 ` TB
2011-05-06 16:53 ` Stephen Hemminger
2011-05-06 17:39 ` TB [this message]
2011-05-11 14:49 ` TB
2011-05-11 15:22 ` Stephen Hemminger
2011-05-11 15:35 ` TB
2011-05-08 22:52 ` David Miller
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