Re: [RFC] exponential update_wall_time

[Roman Zippel <zippel@linux-m68k.org>]

Hi,

On Wed, 27 Sep 2006, john stultz wrote:

> Accumulate time in update_wall_time exponentially. 
> This avoids long running loops seen with the dynticks patch
> as well as the problematic hang" seen on systems with broken 
> clocksources.

This is the wrong approach, second_overflow() should be called every HZ
increment steps and your patch breaks this.
There are other approaches oo accommodate dyntick. 
1. You could make HZ in ntp_update_frequency() dynamic and thus reduce the 
frequency with which update_wall_time() needs to be called (Note that 
other clock variables like cycle_interval have to be adjusted as well). 
2. If dynticks stops the timer interrupt for a long time, it could 
precalculate a few things, e.g. it could complete the second and then 
advance the time in full seconds.

bye, Roman
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