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

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Message-ID: <5170AF2B.80600@linux.intel.com>
Date:	Thu, 18 Apr 2013 19:42:51 -0700
From:	Darren Hart <dvhart@...ux.intel.com>
To:	zhang.yi20@....com.cn
CC:	Dave Hansen <dave@...1.net>, Dave Hansen <dave@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] futex: bugfix for futex-key conflict when futex use hugepage

On 04/18/2013 07:13 PM, zhang.yi20@....com.cn wrote:
> Darren Hart <dvhart@...ux.intel.com> wrote on 2013/04/18 22:34:29:
> 
>> On 04/18/2013 01:05 AM, zhang.yi20@....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
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