EDMA lockup because of huge memset()

Hi, 

I need help to understand a case of EDMA lockup because of memset() of
huge memory size. 

I have a audio playback task which does a SIO_issue() and SIO_reclaim() on
the audio buffers. This task is running with the highest priority. The EDMA
dispatcher keeps calling the ISR once the EDMA has completed the transfer.
Hence SIO_reclaim is successful. 
Now this works fine. But if a low priority task is doing memset() of say
6MB, i occasionally lose interrupts and EDMA seems to be locked up. So the
audio playback task hangs in SIO_reclaim().  

Any help regarding this will be greatly appreciated. 

Thanks,
Nitin   

nitinmpai <nitinmpai@gmail.com> wrote:
 
> I need help to understand a case of EDMA lockup because of 
> memset() of huge memory size. 
 
> I have a audio playback task which does a SIO_issue() and 
> SIO_reclaim() on the audio buffers. This task is running with 
> the highest priority. The EDMA dispatcher keeps calling the ISR 
> once the EDMA has completed the transfer.  Hence SIO_reclaim is 
> successful. 

> Now this works fine. But if a low priority task is doing memset() 
> of say > 6MB, i occasionally lose interrupts and EDMA seems to be 
> locked up. So the > audio playback task hangs in SIO_reclaim().  

Many processor that have a single instruction to implement a
large block operation, such as MVCL in S/370, allow the operation
to be interrupted, and to continue on when the interrupt completes.
It seems that EDMA doesn't allow for that.

-- glen