[Tinyos Core WG] Meeting: 7/11/07

[Philip Levis]

On Jul 11, 2007, at 12:58 PM, John Regehr wrote:

>> PL: Large atomic sections perhaps?
>
> I wrote a bit of code for Avrora (UCLA simulator) that makes a  
> histogram of cycles spent in each atomic section.  Anyone wants  
> this, let me know.  Scanning these results may be a reasonable part  
> of regression testing.  For example this is from RadioCountToLeds  
> from current CVS with the histogram aggregated over all atomics  
> over a 30 seconds run:
>
>   bucket 00 (0000-0099) : 6132
>   bucket 01 (0100-0199) : 135363
>   bucket 02 (0200-0299) : 1177
>   bucket 03 (0300-0399) : 2359
>   bucket 04 (0400-0499) : 158
>   bucket 05 (0500-0599) : 4
>   bucket 06 (0600-0699) : 37
>   bucket 07 (0700-0799) : 0
>   bucket 08 (0800-0899) : 0
>   bucket 09 (0900-0999) : 0
>   bucket 10 (1000-1099) : 0
>   bucket 11 (1100-1199) : 0
>   bucket 12 (1200-1299) : 0
>   bucket 13 (1300-1399) : 118
>   bucket 14 (1400-1499) : 0
>   bucket 15 (1500-1599) : 0
>   bucket 16 (1600-1699) : 0
>   bucket 17 (1700-1799) : 1
>   bucket 18 (1800-1899) : 118
>   bucket 19 (1900-1999) : 0
>   bucket 20 (2000-2099) : 0
>   bucket 21 (2100-2199) : 0
>   bucket 22 (2200-2299) : 0
>   bucket 23 (2300-2399) : 0
>   bucket 24 (2400-2499) : 0
>   bucket 25 (2500-2599) : 0
>   bucket 26 (2600-2699) : 0
>   bucket 27 (2700-2799) : 0
>   bucket 28 (2800-2899) : 0
>   bucket 29 (2900-2999) : 118
>
> (Nothing in any larger bucket.)
>
> A problem is that Avrora only gives results for Mica2.  I will just  
> repeat my plea for a cycle accurate simulator for all major platforms.
>
> The question "How long is too long for an atomic?" is harder in  
> general, though easy for the case of a serial port that interrupts  
> on every byte.  For example at 115 kbps we might expect problems if  
> there are too many atomics longer than ~500 cycles.

Is there any chance your tool could attribute the counts to specific  
atomic sections? That would be very useful.

Phil