RE: [ECOS] RedBoot network timer question

[Gary Thomas <gthomas@cambridge.redhat.com>]

On 18-Jan-2001 Grant Edwards wrote:
> 
> Are the following observations correct?
> 
>  1) The network code keeps track of millisecond "ticks" by
>     delaying for 1ms and incrementing a counter every time any
>     of the code uses the MS_TICKS() to check the current time.
> 
>  2) But, the network polling code is only called once every
>     250ms [the timeout value passed to gets() by the main
>     loop].  I verified this by pinging the board and response
>     times varied from 4m to 290ms with a mean of 144ms.
> 
>  3) That means that the network time only increments by a few
>     milliseconds once every 250ms.  Time would appear to pass
>     very slowly to the network routines, making the TCP
>     timeouts longer by a factor of about 100.
>

Depending on the platform, these observations vary in their correctness.
Some platforms have running timers which the delay routines simply
monitor.  Others will actually simply wait.

Point of observation: timers in the RedBoot stack are meant to keep
things from hanging up, not meant to be necessarily "wallclock" accurate.
If you can tell me how to implement such [accurate] timers without using 
interrupts [and with reasonable overheads], I'm all ears.