Date: Fri, 25 Nov 2005 13:04:23 +0530
From: Dinakar Guniguntala <dino@in.ibm.com>
To: david singleton <dsingleton@mvista.com>
Cc: "David F. Carlson" <dave@chronolytics.com>, linux-kernel@vger.kernel.org,
       Ingo Molnar <mingo@elte.hu>
Subject: Re: PI BUG with -rt13
Message-ID: <20051125073423.GA4825@in.ibm.com>
Reply-To: dino@in.ibm.com
References: <20051118132715.GA3314@elte.hu> <8311ADE9-5855-11DA-BBAB-000A959BB91E@mvista.com> <20051118174454.GA2793@elte.hu> <43822480.6080301@mvista.com> <20051121212653.GA6143@elte.hu> <EDDB1894-5AFB-11DA-A840-000A959BB91E@mvista.com> <20051124145734.GA2717@elte.hu> <20051124202637.GB9098@in.ibm.com> <20051124203250.GA9086@in.ibm.com> <C9607B8E-5D6F-11DA-90F9-000A959BB91E@mvista.com>
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On Thu, Nov 24, 2005 at 08:56:06PM -0800, david singleton wrote:
> On Nov 24, 2005, at 12:32 PM, Dinakar Guniguntala wrote:
> 
> >>I just noticed with the above fix, Paul's testcase completely
> >>hangs up and when killed I hit the BUG mentioned below.
> >>Till -rt13, this testcase just ran to completion
> >
> >Forgot to mention that I notice the same failure with -rt15 as well
> 
> Good news and bad news.
> Good news.  This test doesn't exercise the robust futex code.
> Pthread mutexes that want priority queuing, priority inheritance and/or 
> robustness must have either  the robust (PTHREAD_MUTEX_ROBUST_NP) 
> attribute set and/or the PTHREAD_PRIO_INHERIT attribute set at mutex
> creation time.

Davi, Thank you for looking into this

Yes, this particular testcase does not exercise the robust futex code.
However, the testcase only hangs when I apply your fix on top of
 -rt13. A Vanilla -rt13 works fine

> Now a question before the bad news,    Are you in the OOM path when you
> think the system is hung?  What does 'top' say about freemem and 
> available and used swap space?

Since one of the threads is a SCHED_FIFO, the system takes forever
to respond to simple commands like ls/ps. I'll get back on this

> 
> If you are not in the OOM path then the bad news is this looks like an 
> SMP timer problem.
> 

	-Dinakar
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