[En-Nut-Discussion] Can a thread determine its stack space?

[uprinz2 at netscape.net]

Hi Henrik,


I found these defines but expected them to exist as a nutconf option or at least as a prepared 
//  #define NUTDEBUG_USE_ASSERT

But ok, what I wanted was this:
stack_avail = (uint32_t)((uptr_t) tdp->td_sp - (uptr_t) tdp->td_memory)


The advance of static size_t StackAvail(NUTTHREADINFO *td) if the above define is enabled is, that it checks the lowest stack size until its call by tracing for the 0xDEADBEEF pattern.


Hmmm, it doesn't work...


Here it comes:
Most of the source files do not include osdebug.h nor nutdebug.h so defining this NUTDEBUG_CHECK_STACK doesn't have any effect. 
osdebug.h doesn't include nutdebug.h so some simple checking and breaking / asserting isn't possible.


That's the reason why NUTDEBUG_CHECK_STACK enabled in one file at my place leads to just returning 20 bytes free for all threads. This doesn't change even if I set the threaads stack x3 or x4.


I'll think this has to be reworked a bit.


But thanks for pushing me into the right direction, Henrik


Best regards
Ulrich




-----Original Message-----
From: Henrik Maier <hmnews at proconx.com>
To: 'Ethernut User Chat (English)' <en-nut-discussion at egnite.de>
Sent: Thu, Sep 23, 2010 1:51 am
Subject: Re: [En-Nut-Discussion] Can a thread determine its stack space?


Hi Ulrich,

If you enable just NUTDEBUG_CHECK_STACK during system build,
NutThreadStackAvailable() tells you how much unused stack is available for a
given thread.

This is done using a pattern check for the DEADBEEF pattern. This has no
other performance or code impact to a system than that the stack is filled
with a pattern upon creation in NutThreadCreate().

Refer to context.c and thread.c source code.

Henrik


> -----Original Message-----
> From: en-nut-discussion-bounces at egnite.de [mailto:en-nut-discussion-
> bounces at egnite.de] On Behalf Of Ulrich Prinz
> Sent: Thursday, 23 September 2010 6:13 AM
> To: Ethernut User Chat (English)
> Subject: [En-Nut-Discussion] Can a thread determine its stack space?
> 
> Hi!
> 
> Can a stack determine its own stack space? I.e. I want a thread to
> monitor its own left free stack space. But I cannot find out how to do
> that.
> 
> There are functions that are only available if some debug settings are
> enabled. And some of them are never available as the #defines are never
> set and not available through nutconf.
> 
> But enabling heap debugging doesn't solve the problem if a thread
> silently hangs up while the rest of the system is still running fine.
> And the output of NutHeapAvailable() and NutHeapRootRegionAvailable()
> in the main thread still show plenty of memory.
> 
> Is there a mechanism to find a mutex where a thread is blocked on?
> 
> Enabling debugging has another problem too as it multiplies some stacks
> for init and main and others with a factor what has a general impact on
> the system. So it is difficult to find the problem in a surrounding
> that
> is different from what you target on.
> This might also get difficult if your application needs most of FLASH
> and RAM.
> 
> Best regards
> Ulrich
> _______________________________________________
> http://lists.egnite.de/mailman/listinfo/en-nut-discussion

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