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SubjectRe: AIM7 40% regression with 2.6.26-rc1
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On Thu, 2008-05-08 at 11:21 +0200, Ingo Molnar wrote:
> * 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
A quick test showed it does work.

Thanks. I need to take shuttle bus or I need walk to home for 2 hours if missing it. :)

>
> 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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