OpenAFS Master Repository branch, openafs-stable-1_6_x, updated. openafs-devel-1_5_77-117-g4463034

[Gerrit Code Review]

The following commit has been merged in the openafs-stable-1_6_x branch:
commit 4463034235ff875f59966a61261dc904a92004dc
Author: Simon Wilkinson <sxw@your-file-system.com>
Date:   Sat Oct 23 14:51:56 2010 +0100

    rx: More improvments to RTT calculation
    
    Move the decision about whether a packet contributes to the peer's
    rount trip time into the CalculateRoundTripTime function, and improve
    the criteria used.
    
    Previously, we only computed the RTT if we had not retransmitted. This
    is bad, because it means that places where we have backed off in order
    to retransmit never actually lengthen the RTT, and so the RTT is kept
    artificially low, and we see a large number of retransmits. Instead,
    use the serial of the ACK packet to determine which transmission is
    being acknowledged, and if it is the first, or the last, transmission
    use the appropriate sent time to calculate the RTT.
    
    If we have no serial in the ACK (for a delayed ack, for example), or
    if the serial doesn't match (where a single acknowledgement is soft
    acking a number of packets), fall back to only using the ack if the
    packet has not be retransmitted.
    
    Also, avoid multiple counting of packets which have arrived as part
    of a jumbogram by only permitting the last packet in a jumbogram to
    contribute to the RTT. This avoids giving the RTT of jumbograms more
    weight than those of normal packets - doing so would pull down the
    RTT, as it in effect favours packets which have not be retransmitted.
    
    Reviewed-by: Derrick Brashear <shadow@dementia.org>
    Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
    Tested-by: Jeffrey Altman <jaltman@openafs.org>
    (cherry picked from commit 290495fab1b2a8f1dc842cb2dd6de2d9922169c6)
    Change-Id: I13fef02ad3c456614cd71227e6a0ae8b4a3f5c72
    Reviewed-on: http://gerrit.openafs.org/3127
    Tested-by: Derrick Brashear <shadow@dementia.org>

 src/rx/rx.c |   51 ++++++++++++++++++++++++++++++++++++++-------------
 1 files changed, 38 insertions(+), 13 deletions(-)

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