OpenAFS Master Repository branch, master, updated. openafs-devel-1_5_76-4097-g9a0a8ca

[Gerrit Code Review]

The following commit has been merged in the master branch:
commit 9a0a8ca4d186cf953b87d9fae1a35f66090b060c
Author: Andrew Deason <adeason@sinenomine.net>
Date:   Thu Apr 4 17:35:01 2013 -0500

    viced: Avoid issuing redundant TMAY requests
    
    Currently, if a new Rx connection comes in from a host we already have
    a host struct for, we make a TellMeAboutYourself (TMAY) call to the
    given host, to verify the UUID (and caps, interface info, etc) is what
    we expect it to be. That is, if it's still the "same" host that we
    know about. This is necessary because we otherwise have no way of
    telling if the Rx connection is from the same host, or from a new host
    that just happens to have the same IP address (e.g. in the case that
    hosts are moving around and changing IPs). We do this while the host
    is locked, so we only issue these TMAY calls one at a time.
    
    If a large number of Rx connections come in from the same host at
    around the same time, this can result in a lot of TMAY requests being
    issued against the host, even for hosts that never change IPs and
    never do anything strange. In these situations, issuing so many TMAYs
    is useless. If we have several calls waiting to lock the host to issue
    a TMAY, some of the extra TMAY calls are provably useless. So instead
    of calling TMAY repeatedly, remember what the last successful TMAY
    result was, and reuse it for the "provably useless" calls.
    
    Note that this 'cache' stores the actual raw results of
    TellMeAboutYourself. We could save some memory by storing just how we
    interpret that data later on in h_GetHost_r, but this way results in
    way simpler h_GetHost_r logic. Since, we can use the same code paths
    as for a "real" TMAY call.
    
    Change-Id: I6df74e625e90499bd64c9eb34f20db440f6605a6
    Reviewed-on: http://gerrit.openafs.org/9711
    Tested-by: BuildBot <buildbot@rampaginggeek.com>
    Reviewed-by: Derrick Brashear <shadow@your-file-system.com>

 src/viced/host.c |  243 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 src/viced/host.h |    6 ++
 2 files changed, 245 insertions(+), 4 deletions(-)

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