Thanks for the insight into the problem. The thing is that I have a task
scheduler, a linked list that, well, lists the tasks to perform... Since
linked lists are dynamic in nature, I need malloc to create the new "task"
and append it to the list.. And after the task is done, I free the task and
go on to the next one... The other place I use linked lists is to maintain
a list of timers that the application uses to signal certain events... after
the timer activates, it also gets freed...
So that is why I need malloc and can't (or don't know how) to do it with
other types of dynamic storage, or static. (On that subject, what other
types of dynamic storage exist?)
On Fri, Aug 19, 2011 at 10:49 AM, JMGross <[email protected]> wrote:
>
>
> ----- Ursprüngliche Nachricht -----
> Von: Sergio Campamá
> Gesendet am: 19 Aug 2011 14:39:52
>
> > I am currently building a somewhat complex application for the MSP430,
> and
> > it randomly crashes and I don't seem to know why. I have a suspicion that
> > it's RAM related, because I call many mallocs (I have checked that I free
> > the memory after it's no longer needed), but maybe I am filling up the
> RAM
> > and when it does, it crashes... How can I check at runtime the amount of
> > memory free in RAM? Is there any function that will tell me this?
>
> the problem with malloc is that it can easily cause heap congestion.
> If you always malloc and free the same size, it isn't a problem. But when
> you have different zizes and do not free them in reverse order, you might
> end up with one used byte here, one used byte there and in between
> not enough space for the next malloc.
> It's always a good thing to bail out if malloc returns null.
> I use malloc too, but only for dynamically reserving data space that is
> never freed again (but not known at compile-time).
> (well, that's not entirely true, my multithreader reserves stack space for
> new threads dynamically, and threads may end, freeing this space again. But
> in my projects no thread ever ends)
>
> Also, malloc needs some bytes additional ram for organization. I don't know
> the MSP implementation, but unde rDOS, it was using space immediately before
> the allocated ram, so a free can check whether you're
> freeing a malloced object, and may also join freed areas. All used and free
> areas form a chain, connecteed by this data. And even if the MSP
> implementation does not use full 16 bytes for each data block (as DOS did),
> it is still wasted ram (and you have to store the pointer to it in a
> variable too, so more space needed).
> You should consider other types of dynamic data storage. Or a static
> storage mechanism.
>
> JMGross
>
>
>
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--
--------------------------------------
Sergio Campamá
[email protected]
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