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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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