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    SubjectRe: AIM7 40% regression with 2.6.26-rc1

    * Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:

    > > disk_cp /mnt/shm
    > > disk_cp (1): cannot open /mnt/shm/tmpa.common
    > > disk1.c: No such file or directory
    > >
    > > [.. etc. a large stream of them .. ]
    > >
    > > system has 2GB of RAM and tmpfs mounted to the place where aim7 puts its
    > > work files.

    > My machine has 8GB. To simulate your environment, I reserve 6GB for
    > hugetlb, then reran the testing and didn't see any failure except: AIM
    > Multiuser Benchmark - Suite VII Run Beginning
    >
    > Tasks jobs/min jti jobs/min/task real cpu
    > 2000create_shared_memory(): can't create semaphore, pausing...
    > create_shared_memory(): can't create semaphore, pausing...

    that failure message you got worries me - it indicates that your test
    ran out of IPC semaphores. You can fix it via upping the semaphore
    limits via:

    echo "500 32000 128 512" > /proc/sys/kernel/sem

    could you check that you still get similar results with this limit
    fixed?

    note that once i've fixed the semaphore limits it started running fine
    here. And i see zero idle time during the run on a quad core box.

    here are my numbers:

    # on v2.6.26-rc1-166-gc0a1811

    Tasks Jobs/Min JTI Real CPU Jobs/sec/task
    2000 55851.4 93 208.4 793.6 0.4654 # BKL: sleep
    2000 55402.2 79 210.1 800.1 0.4617

    2000 55728.4 93 208.9 795.5 0.4644 # BKL: spin
    2000 55787.2 93 208.7 794.5 0.4649 #

    so the results are the same within noise.

    I'll also check this workload on an 8-way box to make sure it's OK on
    larger CPU counts too.

    could you double-check your test?

    plus a tty tidbit as well, during the test i saw a few of these:

    Warning: dev (tty1) tty->count(639) != #fd's(638) in release_dev
    Warning: dev (tty1) tty->count(462) != #fd's(463) in release_dev
    Warning: dev (tty1) tty->count(274) != #fd's(275) in release_dev
    Warning: dev (tty1) tty->count(4) != #fd's(3) in release_dev
    Warning: dev (tty1) tty->count(164) != #fd's(163) in release_dev

    Ingo


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