Memory allocation within a clock instance function

Ashish,

I tried changing the C Standard Library Lock to GateSwi, but malloc() calls in a clock function still block. I also tried GateHwi and NoLocking but no luck there either. Are any other SYSBIOS settings needed or could any SYSBIOS settings conflict with changing the Library Lock?

Thanks,

Chris

Ashish-

It appears our call to malloc() from within a clock instance (SWI task) can't get the mutex, so it hangs.  As Chris mentions we've tried the various "C Standard Library Lock" options in SYSBIOS config.

Question -- when our clock instance task runs the first time, who else has the mutex?  Is SYSBIOS need malloc at that point?  There are no other tasks, just the one clock instance task we create dynamically in main().

Thanks.

-Jeff

Hi Chris,

Chris Johnson1 said:

I tried changing the C Standard Library Lock to GateSwi, but malloc() calls in a clock function still block. I also tried GateHwi and NoLocking but no luck there either. Are any other SYSBIOS settings needed or could any SYSBIOS settings conflict with changing the Library Lock?

If you change the lock type to GateSwi, then when you call malloc() from within your clock swi function, the rts_lock() function internally calls GateSwi_enter() which simply does a Swi_disable() and returns. If an interrupt occurs just before the Swi_disable() completes and posts a higher priority swi, the higher priority swi will execute first but the execution will return to the malloc() and the malloc() call will complete. The clock swi function cannot block if GateSwi is used as the library lock.

How are you concluding that the clock swi function is blocking ?

Best,

Ashish

Ashish,

I have a section of code that looks something like this:

probe |= 1;

if (ptr = malloc()){ 
   probe |= 2;
   ...
}

probe |= 4;
 
When I read back the value of probe it is 1, so it doesn't look like it gets past the malloc() call. Could the issue be that I don't have the write memory/heap modules in use or setup properly? I am not using the Memory module or any of the Heap modules for SYS/BIOS. I just have the Heap size and Heap section set in the SYS/BIOS basic runtime options where it says "The heap configured above is used for standard C malloc() and free() functions...".

Thanks,

Chris

Ashish-

A few more data points:

1) If our code is not inside a clock instance task, it runs Ok.  No change in malloc() etc.  Mem allocation is done on the first run of the task only, after that we make calls to TI multimedia codecs.  Only in the clock instance task does malloc() hang.

2) The task runs every 5 msec.  There are no other tasks.

3) We assume "Add Memory Management" (in SYSBIOS Memory config) should not be checked.  We just want to use the standard heap (HeapStd).

4) Should we see any reference to HeapStd in the .map file?

5) What section name should be used for "BIOS.heapSection" in the SYSBIOS .cfg file?

Thanks.

-Jeff

Ashish-

Thanks again for your reply, we will try this.  To clarify, is HeapMem required?  HeapStd doesn't support calling malloc() from an SWI?

-Jeff

Thanks Ashish, that did the trick.

Chris

Hi Jeff,

Yes, I believe your application is using HeapMem as the heap manager. You could change the heap manager to HeapStd and make malloc() calls from Swi but I would recommend you to continue using HeapMem. We discourage using HeapStd and may even stop supporting HeapStd with SYS/BIOS in the future.

Best,

Ashish

Ashish-

Ok got this.  We will stick with HeapMem from this point forward.  Thanks again.

-Jeff
Signalogic