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stack sizes again

Posted by Ben on October 29, 2007
I have searched many of the threads here looking for and answer but have not had to much luck.

I am using FreeRTOS on an lpc2368 arm7 core.

In xTaskCreate, the usStackDepth is in multiple of stack width. So for the arm7 this would be multiple of 4 bytes.

e.g usStackDepth = 100 = 100 * 4 bytes

That I understand ( i hope), although in one post I found it said that for a 32 bit stack and allocating 100 elements the size would be 32 x 100 - I assume that was in bits.

I am using vTaskList() to display task info. From the online manual -

Lists all the current tasks, along with their current state and stack usage high water mark.

Now just what is meant by the high water mark. From what I am seeing I think it is the amount of free space on the stack, because the more I allocate in xTaskCreate, the larger this value seems to get.

Also is this value in bytes or in stack widths ?

many thanks

RE: stack sizes again

Posted by Richard on October 29, 2007
The number is in bytes, not words. It is the number of bytes that have not ever been used. For example, if you stack is 100 bytes total, and the most you have ever actually used is 75 bytes, then the high water mark shown will be 25. Therefore, when this values reaches near zero, you know you have a problem!


RE: stack sizes again

Posted by Ben on October 30, 2007
ok thanks, i thought that was probably what I was seeing, but wanted to make sure as I am having some funny problems, possibly stack related.


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