Messages in this thread | | | Date | Fri, 06 May 2011 13:39:53 -0400 | From | TB <> | Subject | Re: [PATCH] tcp_cubic: limit delayed_ack ratio to prevent divide error |
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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
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