[ECOS] Pthread problem

[ECOS] Pthread problem

[Davies, Greg]

Hi,
	I'm having problems when I try to run more than two pthreads at
the same time. This is on a SAM7SE-EK board using the SAM7S-EK eCos
configuration. 

	The threads start up correctly and I hit the main loop of all of
them. Inside each main loop is a sched_yield() after it's done the main
work. After the last thread yields, control never returns to one of my
threads. I tried taking out all the yields, and letting ecos' preemption
take care of when to switch context, but when I do that, I only ever hit
the main loop of one of my threads. I also thought it might be a problem
with the priority of the created threads being lower than that of the
idle thread, but I haven't explored that possibility yet. 

	Is there something different about the way pthreads work in eCos
(the same code ran in linux)? I using the library the way I should be,
should I be sleeping instead of yielding? Could there be a configuration
item that could be causing this?

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Re: [ECOS] Pthread problem

[Enno Lübbers]

Hi,

have you tried using eCos threads instead of pthreads? The pthreads  
implementation uses Cyg_Threads, so this way you could determine if  
it's a compat/posix-related problem or whether maybe your eCos  
scheduler config (or something similar) is wrong.

Regards,
- Enno
-- 
Dipl.-Ing. Enno Luebbers
Computer Science Department
University of Paderborn	

Warburger Str. 100		
33098 Paderborn			

http://wwwcs.upb.de/cs/ag-platzner
phone:  05251 / 60-5397
fax:    05251 / 60-5377


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Re: [ECOS] Pthread problem

[Andrew Lunn]

On Thu, Feb 14, 2008 at 09:07:05AM -0400, Davies, Greg wrote:
> Hi,
> 	I'm having problems when I try to run more than two pthreads at
> the same time. This is on a SAM7SE-EK board using the SAM7S-EK eCos
> configuration. 
> 
> 	The threads start up correctly and I hit the main loop of all of
> them. Inside each main loop is a sched_yield() after it's done the main
> work. After the last thread yields, control never returns to one of my
> threads. I tried taking out all the yields, and letting ecos' preemption
> take care of when to switch context, but when I do that, I only ever hit
> the main loop of one of my threads. I also thought it might be a problem
> with the priority of the created threads being lower than that of the
> idle thread, but I haven't explored that possibility yet. 
> 
> 	Is there something different about the way pthreads work in eCos
> (the same code ran in linux)? I using the library the way I should be,
> should I be sleeping instead of yielding? Could there be a configuration
> item that could be causing this?

Problems like this are typically to do with the stack being too small
and you overwrite the thread structure. Turn on INFRA_DEBUG and try
with bigger stacks.

     Andrew

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RE: [ECOS] Pthread problem

[Davies, Greg]

> On Thu, Feb 14, 2008 at 09:07:05AM -0400, Davies, Greg wrote:
> > Hi,
> > 	I'm having problems when I try to run more than two 
> pthreads at the 
> > same time. This is on a SAM7SE-EK board using the SAM7S-EK eCos 
> > configuration.
> 
> Problems like this are typically to do with the stack being 
> too small and you overwrite the thread structure. Turn on 
> INFRA_DEBUG and try with bigger stacks.
> 
>      Andrew

I had tried the stack thing before, but it didn't help. In some cases when I made it too big, it caused my debugger to stop working. I turned on some of the debugging features and some other things, and it started working. I'm not sure exactly which option made it start working again though. I think that's a story for another day. 

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Re: [ECOS] Pthread problem

[Gary Thomas]

Davies, Greg wrote:
>> -----Original Message-----
>> From: Gary Thomas [mailto:gary@mlbassoc.com] 
>> Sent: Friday, February 15, 2008 4:19 PM
>> Have you tried running the standard eCos pthread examples?
>> In particular, 'pthread2' tests just what you seem to be 
>> having trouble with.
>>
>>    # make -C compat/posix/current tests
>>
> I didn't even realise there were pthreads examples. I must have missed
> those somehow. I definitely check those Monday.
> 

Indeed, there are unit tests for most everything in eCos :-)

Of course, if there's something you think needs to be tested
further, feel free to contribute some code!

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

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RE: [ECOS] Pthread problem

[Davies, Greg]

> -----Original Message-----
> From: Gary Thomas [mailto:gary@mlbassoc.com] 
> Sent: Friday, February 15, 2008 4:19 PM
> Have you tried running the standard eCos pthread examples?
> In particular, 'pthread2' tests just what you seem to be 
> having trouble with.
> 
>    # make -C compat/posix/current tests
> 
I didn't even realise there were pthreads examples. I must have missed
those somehow. I definitely check those Monday.

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Re: [ECOS] Pthread problem

[Gary Thomas]

Davies, Greg wrote:
> -----Original Message-----
> From: Enno Lübbers [mailto:enno.luebbers@upb.de]
> Sent: Thursday, February 14, 2008 3:21 PM
> 
> have you tried using eCos threads instead of pthreads? The pthreads implementation uses Cyg_Threads, so this way you could determine if it's a compat/posix-related problem or whether maybe your eCos scheduler config (or something similar) is wrong.
> 
> 
> Thanks for the suggestion. I tried to run the simple two thread example from the documentation, but I couldn't get it to run. The problem with trying this is that the pthreads are kind of wrapped up in everything, so by the time I get my configuration to the point where I can use Cyg_Threads, I'm debugging a whole different application. I'm going to see if they can run side by side today. I figure that's my best bet.
> 

Have you tried running the standard eCos pthread examples?
In particular, 'pthread2' tests just what you seem to be
having trouble with.

   # make -C compat/posix/current tests

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

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RE: [ECOS] Pthread problem

[Davies, Greg]

-----Original Message-----
From: Enno Lübbers [mailto:enno.luebbers@upb.de]
Sent: Thursday, February 14, 2008 3:21 PM

have you tried using eCos threads instead of pthreads? The pthreads implementation uses Cyg_Threads, so this way you could determine if it's a compat/posix-related problem or whether maybe your eCos scheduler config (or something similar) is wrong.


Thanks for the suggestion. I tried to run the simple two thread example from the documentation, but I couldn't get it to run. The problem with trying this is that the pthreads are kind of wrapped up in everything, so by the time I get my configuration to the point where I can use Cyg_Threads, I'm debugging a whole different application. I'm going to see if they can run side by side today. I figure that's my best bet.

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