[Tinyos-devel] nesC concurrency semantics, volatiles, etc.

[Philip Levis]

On Aug 11, 2006, at 8:33 PM, John Regehr wrote:

>
> Side node: Anyone know what constitutes an unacceptable performance  
> lose
> for an "average" TinyOS app?  I mean, if the duty cycle of a mote goes
> from 5% to 6% then this is a huge slowdown but it may matter very  
> little
> in terms of decreased battery lifetime.  Clearly there'll always be  
> some
> apps that are maxing out the MCU but these shouldn't be too common.

Generally, performance hits matter much more with respect to the  
running time of an interrupt handler than overall CPU utilization.  
Slowing down the FIFOP interrupt in the reception path, for example,  
might not add a significant amount of CPU overhead to an application  
overall, but it may cause a node to drop packets. Similarly, reducing  
the maximum ADC sampling rate from 8kHz to 2kHz is a big deal,  
although in both cases you'd (theoretically) be using the CPU close  
to 100%.

Phil