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  1. Lustre
  2. LU-8786

Terrible i/o performance of a test application doing repeatable writes and truncates

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    • Bug
    • Resolution: Duplicate
    • Major
    • None
    • None
    • None
    • 3
    • 9223372036854775807

    Description

      A customer application benchmark required for acceptance testing shows terrible i/o performance. A simple test case was created to mimic the customer application behavior. This test never completes when run with a walltime limit of 30 minutes (job is killed after walltime exceeded); the same test run to the /tmp fs on the client node completes within a few seconds.
      The tests completes in few seconds in Lustre-2.1.

       program iotest
            PARAMETER (NA=6400)
            dimension IA(NA)
            call init (IA,NA)
            call sleep(1)
            open (unit=22, file='time.step')
            do i=1,na
            call my_write(iA,NA,i)
            end do
            STOP
            END
            SUBROUTINE my_write(IA,NA,I)
            dimension ia(na)
            kt=ia(i)
            WRITE ( 22, '(1x, i8)' )   kt
            REWIND (22)
            return
            end
            subroutine init(IA,NA)
            dimension iA(na)
            do i=1,NA
            ia(i)=i
            end do
            return
            end
      

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              wc-triage WC Triage
              zam Alexander Zarochentsev
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                Updated:
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