Szentirmai Gergely wrote:
Hello
I had a bad feeling about stack usage (perhaps measurement), and I have
written a small testcode, to see what's really happening. It came with
an interesting result. It seems to me, that cyg_thread_info.stack_used
gives the max used stack size, not the actual. Is that right? According
to the docs, it should give the current usage.
The test code is attached, I use arm-elf-gcc, ecos with default packages.
The result is also attached. I think that even the last stack usage
should be equal with 144 Bytes.
Maybe I am wrong... maybe not.
No, you are correct, the value is the maximum used. Why is this
less useful than the 'current' used? Stacks aren't reused or
dynamic (they don't grow or shrink), so [IMO] the most useful
measurement is the max size you'll ever need, which is the
measured value [at the time of the measurement, of course]
In addition, every call your code makes to 'diag_printf()'
perturbs the measurement, as it can use a lot of stack itself!
If you want to be very pure about the measurements, save the
stack information in some variables and only print the results
when done, that way 'diag_printf()'s use won't get in the way.