On 09/04/15 14:00, Joel Sherrill wrote:
On April 9, 2015 4:11:14 AM CDT, Alexander 
Krutwig<alexander.krut...@embedded-brains.de>  wrote:
>Hello,
>
>the newest Timecounter patch was sent yesterday. As of now, the
>replacement of the nanoseconds extension with FreeBSD timecounters will
>
>also be started for the remaining BSPs. Exemplarily, the changes for
>the
>ERC32-BSP are given in the patch.
Nice to see this coming along so fast. Any thoughts on the impact of variable length 
clock ticks? This is often referred to as tickless but I am not as concerned with the use 
case of dynamically reprogramming the clock tick quantum as advancing time to account for 
being in a virtualized environment and your "container" not running for a while.


In terms of support for tickless systems the situation is slightly better. With the nanoseconds extensions this would simply not work. With the timecounters it depends on the hardware capabilities. In a tickless system large time steps can occur (e.g. you sleep one minute in powerdown mode, then wake up, now you have a 1 minute time step). In case this time step is larger than your hardware timer interval, then you have a problem.

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Sebastian Huber, embedded brains GmbH

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