TMS320C6746: Issue on DDR memory allocation using HeapBuf_alloc function

Hi,

What are you passing for the Error_Block in the Memory_alloc. Did you initialize it?

When you get NULL back from Memory_alloc, how do you know there is actually memory in the heap?

I don't think this is a multi-thread issue since it looks in IRAM and we have not had any issues with HeapBuf for years.

Todd

Hi,

Thanks for your response

Error block variable is declared but not initialized, will it be an issue?

Available free space is checked as below before allocating memory

Thanks for the code snippet. I see a few things

1. Please use Memory_alloc instead of directly calling HeapBuf_alloc.

2. Please initialize the Error_Block before using it. Here is how to do it.

Error_init(&eb);

3. Are you seeing DataPkt be NULL?

4. Your code is not thread-safe. You could see there is memory present (via the HeapBuf_getStats), but then before you call the alloc, a higher priority thread runs and allocates all the memory from the heap. Then when the above task returns, there is no memory. Could this be happening? I'm assuming you are only allocating memory from tasks. You can put a Task_disable before you get the stats and Task_restore after you allocate the memory (and in the if no memory case).

5. You are using TLMBuffer in the HeapBuf_getStats and Buffer in HeapBuf_alloc...are these two the same thing?

Todd

Hi ,

Thanks for your great findings and find my answer's  in Pink   

Please find below changes as per your recommendation, please review and let us know if we missed anything, We will stat testing this changes soon.

1.Please use Memory_alloc instead of directly calling HeapBuf_alloc.

Veera: I tired Memory_alloc, but no help, any way i will try once again along with all changes as per your recommendation .

2. Please initialize the Error_Block before using it. Here is how to do it.

3. Are you seeing DataPkt be NULL?

Veera : Yes

4. Your code is not thread-safe. You could see there is memory present (via the HeapBuf_getStats), but then before you call the alloc, a higher priority thread runs and allocates all the memory from the heap. Then when the above task returns, there is no memory. Could this be happening? I'm assuming you are only allocating memory from tasks. You can put a Task_disable before you get the stats and Task_restore after you allocate the memory (and in the if no memory case).

Veera: I agree and it is very much valid point, We will try to accommodate in our code and test it .

5. You are using TLMBuffer in the HeapBuf_getStats and Buffer in HeapBuf_alloc...are these two the same thing?

Veera: this is a typo error, I edited original variable name because we were trying to not to disclose original variable name.. Sorry.

Thanks 

Veera

Uint8 QueueDataPacket(UpdatePacket *CurrPacket){ UpdatePacket *DataPkt; Error_Block eb; Memory_Stats stats; Error_init(&eb); Uint32 key; key=Task_disable(); /* Get the un-Used buffer count */ HeapBuf_getStats(Buffer,&stats); /* If no buffer is free, return */ if (stats.totalFreeSize < TLM_BUF_BLOCKSIZE) { return FALSE; } /* Allocate buffer from the Event Buffer pool */ DataPkt=(UpdatePacket *)Memory_alloc(xdc_runtime_IHeap_Handle(Buffer),BUF_BLOCKSIZE,8,&eb);
/* Copy the Current packet into the buffer */ memcpy(DataPkt,CurrPacket, sizeof(TlmUpdatePacket)); Task_restore (key); /* Queue the packet */ Queue_put(TQue,(Queue_Elem *)DataPkt);
return TRUE;}

Make sure to add the Task_restore in the "if" case also (before you return FALSE).

yes i did that 

Thanks and I really appreciate your response 

Veera

Hi 

We have tested as we discussed , but problem remains same.

one more point i want to add earlier Discussion, 

 We have added code to skip the Queuing if it returns Null pointer,  But Memory_alloc function continuously returns null pointer once this condition occur.it can recover only when if we reset the processor.

Thanks & Regards

Veera

veerakumar Bose1 said:

We have added code to skip the Queuing if it returns Null pointer,  But Memory_alloc function continuously returns null pointer once this condition occur.it can recover only when if we reset the processor.

When do you free the allocated memory?

Have you look at HeapBuf in CCS->Tools->ROV?

Just to make sure...since you added the thread-safety, does the Memory_getStats say there is memory, but then the Memory_alloc return NULL?

Todd

Hi,

Please find my answers

When do you free the allocated memory?

Veera: Freeing of allocated memory is handled is another function. That function free the allocated space once buffered data is sent to other module.

Have you look at HeapBuf in CCS->Tools->ROV?

Veera: This condition is not occurring when we run the code in debug mode

Just to make sure...since you added the thread-safety, does the Memory_getStats say there is memory, but then the Memory_alloc return NULL?

Veera : yes

Thanks

Veera

Hi Veera,

Can you get any debug information when the case is hit? Memory browser? I'd like to see the HeapBuf instance when this occurs.

Todd

Hi

As i said earlier this issue will not come when we run the code in debug mode

Veera

But can you get any information? For example, dump the HeapBuf instance memory to something persistent that you can look at later. If not, I'm not sure if there is anything else I can do.

Todd