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    SubjectRe: [PATCH] tcp_cubic: limit delayed_ack ratio to prevent divide error
    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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