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

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Date:	Fri, 19 Apr 2013 10:13:43 +0800
From:	zhang.yi20@....com.cn
To:	Darren Hart <dvhart@...ux.intel.com>
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: Re: [PATCH] futex: bugfix for futex-key conflict when futex use
 hugepage

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.

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