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Date: Tue, 07 Jul 2009 16:13:07 +0200
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-help] pthread_create memory size
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To: Yigal Goldberger <yigal_gold@domain.hid>
Cc: xenomai@xenomai.org

Gilles Chanteperdrix wrote:
> Yigal Goldberger wrote:
>> Hi all,
>> I'm using xenomai  on kernel 2.6.29 on a powerpc based board.
>> I see that when I call : 
>> cat proc/meminfo
>> before pthread_create and after it there is a difference of 2MB in free memory , indicating that the thread is being allocated 2MB of ram (?) .
>>
>> before :
>> MemTotal:       256868 kB
>> MemFree:        227624 kB
>>
>> After :
>> MemTotal:       256868 kB
>> MemFree:        225632 kB
>>
>> I am calling pthread_attr_setstacksize(&attr,8192)
>> before calling pthread_create so it shouldn't be the stack size .
>> Is this the expected memory consuption per thread ? 
>> if not, how can I reduce this ?
> 
> That is explained in the TROUBLESHOOTING guide, use ulimit -s. In fact,
> I suspect the behaviour depends on the version of the glibc you use.

In particular, if using an old glibc with linuxthreads (that is a really
old glibc), the glibc creates an additional thread when creating the
first thread. The 2MB you see maybe the stack of this additional thread.

-- 
                                          Gilles