Re: [PATCH] futex: bugfix for futex-key conflict when futex use hugepage

Darren Hart
2013-04-19T02:43:03Z

On 04/18/2013 07:13 PM, zhang.yi20@zte.com.cn wrote:
> Darren Hart <dvhart@linux.intel.com> wrote on 2013/04/18 22:34:29:
>
>> On 04/18/2013 01:05 AM, zhang.yi20@zte.com.cn wrote:
>>>
>>> I have run futextest/performance/futex_wait for testing,
>>> 5 times before make it long:
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 10215 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 9862 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 10081 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 10060 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 10081 Kiter/s
>>>
>>>
>>> And 5 times after make it long:
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 9940 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 10204 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 9901 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 10152 Kiter/s
>>>
>>> futex_wait: Measure FUTEX_WAIT operations per second
>>> Arguments: iterations=100000000 threads=256
>>> Result: 10060 Kiter/s
>>>
>>>
>>> Seems OK, is it?
>>>
>>
>> Changes appear to be in the noise, no impact with this load
>> anyway.
>> How many CPUs on your test machine? I presume not 256?
>>
>> --
>
> There are 16 CPUs， and mode is:
> Intel(R) Xeon(R) CPU C5528 @ 2.13GHz
>
> Shall I make the number of threads as the CPUS? I test again with argument
> '-n 16', the result is similar.

No, I just wanted to be sure you weren't running 256 threads on 1 CPU as
you wouldn't be likely to be stressing the bucket list much :-)

> BTW, have you seen the testcase in my other mail? It seems to be rejected
> by LKML.

Might have something to do with what appears to still be HTML email. You
really need to fix your email client.

See: http://www.tux.org/lkml/
#12 in particular.

--
Darren Hart
Intel Open Source Technology Center
Yocto Project - Technical Lead - Linux Kernel