From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Wed, 22 Jun 2011 12:55:12 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: Re: [Xenomai-core] User space stack pre-faulting
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: Xenomai core <Xenomai-core@domain.hid>

On 2011-06-22 12:36, Gilles Chanteperdrix wrote:
> On 06/22/2011 11:26 AM, Jan Kiszka wrote:
>> Hi Gilles,
>>
>> do you remember reasons for only pre-faulting the main thread's stack?
>> The desire to avoid wasting resources by forcing all stacks into memory?
>>
>> I've the requirement on my table to provide a generic solution of all
>> shadow threads. I think this should be possible using pthread_getattr_np
>> and walking the stack page-wise, but I may miss some pitfall.
> 
> Last time I checked, only the main thread stack was mapped on demand.
> Other threads have mmaped stacks, which are made present by mlockall,
> so, do not need faulting.

That's definitely not the case in general. Customer has just confirmed
that pre-faulting thread stacks avoids first-access domain switches.

Jan

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