[Tinyos-host-mote-wg] Re: [Tinyos-2.0wg] Timers in 2.x

[Joe Polastre]

On 10/18/05, David Gay <dgay42 at gmail.com> wrote:
> Transformed alarms use the counter, so there's no gain there.  And at
> the lowest level, including both doesn't cost either because dead-code
> elimination will remove the part which isn't used... That only leaves
> transformed counters where the alarm isn't used (which I suggested
> leaving around).

Even if the Alarm isn't used, the interrupt is signalled into that
component and thus adds space for the processing of the Alarm.  This
occurs even if noone wires to the Alarm.  The problem is the
propogation of interrupts (async) from the bottom up through the stack
when it isn't necessary.  Thus, in this case, you do get the extra
code space---dead code elimination doesn't help you there.  This is
especially true when you transform to a 32-bit Alarm when the system
doesn't use the alarm or the user is only accessing the 16-bit
interface.

> All of this is of course up to each platform, but I do think the
> plethora of components is confusing to users...

That's why we have OSKI right?  The lower layers should be expressive
and powerful, the upper layers abstract to a common interface,
potentially with code bloat.

-Joe

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