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    SubjectRe: PROBLEM: Silent data corruption when using sendfile()
    On Sat, Jul 14, 2012 at 10:20:41AM +0200, Eric Dumazet wrote:
    > > On Tue, Jul 3, 2012 at 8:02 AM, Willy Tarreau <w@1wt.eu> wrote:
    > > >
    > > > In fact it has been true zero copy in 2.6.25 until we faced a large
    > > > amount of data corruption and the zero copy was disabled in 2.6.25.X.
    > > > Since then it remained that way until you brought your patches to
    > > > re-instantiate it.
    >
    > Might be, or not (could be a NIC bug)

    I may be wrong but what I recall from this bug was an issue when
    forwarding TCP between two NICs, related to linear vs non-linear
    data (I have memories of something around data not yet ACKed being
    replaced before being retransmitted but I may be wrong). Anyway,
    the way it was fixed consisted in simply disabling the zero-copy
    code path. So this should be something different from what Johannes
    reports. Maybe a regression since then though.

    > Please Johannes could you try latest kernel tree ?

    It would be useful, especially given the amount of changes you performed
    in this area in latest version, it could be very possible that this new
    bug got fixed as a side effect !

    Regards,
    Willy



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