[lkml]   [2012]   [Jun]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRE: [PATCH] sched: Folding nohz load accounting more accurate
    >  On 2012.06.12 02:56 - 0800 (I think), Peter Zijlstra wrote:

    >Also added Doug to CC, hopefully we now have everybody who pokes at this


    On my computer, and from a different thread from yesterday, I let
    the proposed "wang" patch multiple processes test continue for
    another 24 hours. The png file showing the results is attached, also
    available at [1].

    Conclusion: The proposed "wang" patch is worse for the lower load
    conditions, giving higher reported load average errors for the same
    conditions. The proposed "wang" patch tends towards a load equal to
    the number of processes, independent of the actual load of those

    Interestingly, with the "wang" patch I was able to remove the 10
    tick grace period without bad side effects (very minimally tested).

    @ Charles or Tao: If I could ask: What is your expected load for your 16
    processes case? Because you used to get a reported load average of
    < 1, we know that the processes enter and exit idle (sleep) at a high
    frequency (as that was only possible way for the older under reporting
    issue, at least as far as I know). You said it now reports a load
    average of 8 to 10, but that is too low. How many CPU's do you have?
    I have been unable to re-create your situation on my test computer
    (an i7 CPU).
    When I run 16 processes, where each process would use 0.95 of a cpu,
    if the system did not become resource limited, I get a reported load
    average of about 15 to 16. Kernel = 3.5 RC2. Process sleep frequency
    was about 80 Hertz each.


    Doug Smythies

    [unhandled content-type:image/png]
     \ /
      Last update: 2012-06-13 08:41    [W:0.029 / U:15.716 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site