How to find out RAM usage in Embedded Electronic Control Unit (ECU) ?

[jani12]

Please consider some professional embedded system with 16-bit microcontroller.

I know embedded software build tools report program flash memory usage. I think they also report RAM usage but do they report maximum RAM usage?

Build tools may not know how much heap will be used during run-time. Are there other RAM usages that build tools aren't aware of?

How to accurately find out how much RAM is being used during run-time?

 

[Nigel Goodwin]

For a start you need to specify which device you're talking about, as each is likely to be completely different, assuming it's even possible.

From a PIC point of view, it tells you program and data use after compilation, and if it compiles then there doesn't seem to be any memory issues. Obviously if you're doing something stupid (as C allows you to do) then you could easily kill things, but in my experience the compiler seems to reject any memory issues it doesn't like.

 

[Pommie]

I avoid Malloc() for this very reason unless I KNOW how it will be used and released plus, it's frequently leaky - better to allocate required buffers as this assumes worst case - all buffers allocated at the same time.
It's impossible to report run time parameters as, by definition, they're undefined. Same as you can't know if a divide by zero may happen in your code at run-time.

Actually, how can a tool possibly know how much RAM you will allocate at run-time? Mind reading?


Mike.

 

[Nigel Goodwin]

I avoid Malloc() for this very reason unless I KNOW how it will be used and released plus, it's frequently leaky - better to allocate required buffers as this assumes worst case - all buffers allocated at the same time.
It's impossible to report run time parameters as, by definition, they're undefined. Same as you can't know if a divide by zero may happen in your code at run-time.

Actually, how can a tool possibly know how much RAM you will allocate at run-time? Mind reading?


Mike.

I don't think XC8 allows Malloc()

 

[danadak]

Some interesting discussion about this problem :

malloc() with heap overflow explanation

I have the following code: int main(int argc, char *argv[]) { int bufferSize = 8; //Setting the buffer size here, which can cause a heap overflow char *argsStr = malloc(bufferSize);

stackoverflow.com

how does malloc work in details?

I am trying to find some useful information on the malloc function. when I call this function it allocates memory dynamically. it returns the pointer (e.g. the address) to the beginning of the allo...

stackoverflow.com

Memory leak in C (malloc)

to learn Heap memory, I used the following code. I used malloc inside a called function (fn1), and for some I reason, I decided not to free the memory inside the called function (fn1). I passed the

stackoverflow.com

Regards, Dana.

 

[Pommie]

I don't think XC8 allows Malloc()

Thought I'd used it in the past and it turns out, I was right.

5.4.7 Dynamic Memory Allocation

Dynamic memory allocation is a means for programs to manually request and release arbitrary-sized blocks of memory during program execution. It is available in some form for most devices supported by ...

onlinedocs.microchip.com

Check the second paragraph.

Mike.

 

[Nigel Goodwin]

Thought I'd used it in the past and it turns out, I was right.

5.4.7 Dynamic Memory Allocation

Dynamic memory allocation is a means for programs to manually request and release arbitrary-sized blocks of memory during program execution. It is available in some form for most devices supported by ...

onlinedocs.microchip.com

Check the second paragraph.

Mike.

Interesting, I'll have to give it a try sometime

 

[Pommie]

Interesting, I'll have to give it a try sometime

As I said, best to avoid it.

Mike.

 

[Nigel Goodwin]

As I said, best to avoid it.

Mike.

I always have - and have removed it from code I was porting, but if I accidentally left it in, I'm sure it failed compilation? - which is why I might try it one day, just to check (if I get round to it? )