lkml.org 
[lkml]   [2007]   [Dec]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4
    Ingo Molnar wrote:
    > * Jie Chen <chen@jlab.org> wrote:
    >
    >> I just disabled the affinity mask and reran the test. There were no
    >> significant changes for two threads (barrier overhead is around 9
    >> microseconds). As for 8 threads, the barrier overhead actually drops a
    >> little, which is good. Let me know whether I can be any help. Thank
    >> you very much.
    >
    > sorry to be dense, but could you give me instructions how i could remove
    > the affinity mask and test the "barrier overhead" myself? I have built
    > "pthread_sync" and it outputs numbers for me - which one would be the
    > barrier overhead: Reference_time_1 ?
    >
    > Ingo
    Hi, Ingo:

    To disable affinity, do configure --enable-public-release
    --disable-thread_affinity. You should see barrier overhead like the
    following:
    Computing BARRIER time

    Sample_size Average Min Max S.D. Outliers
    20 19.486162 19.482250 19.491400 0.002740 0

    BARRIER time = 19.486162 microseconds +/- 0.005371
    BARRIER overhead = 8.996257 microseconds +/- 0.006575

    The Reference_time_1 is the elapsed time for single thread doing simple
    loop without any synchronization. Thank you.

    --
    ###############################################
    Jie Chen
    Scientific Computing Group
    Thomas Jefferson National Accelerator Facility
    12000, Jefferson Ave.
    Newport News, VA 23606

    (757)269-5046 (office) (757)269-6248 (fax)
    chen@jlab.org
    ###############################################



    \
     
     \ /
      Last update: 2007-12-05 21:55    [W:0.045 / U:31.224 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site