Re: [patch] i386 dynamic ticks 2.6.13-rc4 (code reordered)

Stefan Seyfried
2005-08-08T07:18:35Z

Con Kolivas wrote:

>> When I enabled dynamic tick using:
>>
>> echo 1 > /sys/devices/system/timer/timer0/dyn_tick_state
>>
>> The number of ticks dropped down to 60-70 HZ, bus mastering activity
>> jumpped up to being almost always active,
>
> Anyone know why this would happen?

This is just a guess, without any actual code-reading:
Maybe the C-state decision process just relies on being called every
tick, so "after X ticks with no BM activity, go to next deeper C state".
As long as 1000 ticks per second are coming in, everything is fine and
we enter C[n+1] after X miliseconds without BM activity. Now if there
are only 60-70 ticks per second, you never get X ticks without BM
activity so you never go deeper than C2.

Just a guess.
--
Stefan Seyfried \ "I didn't want to write for pay. I
QA / R&D Team Mobile Devices \ wanted to be paid for what I write."
SUSE LINUX Products GmbH, Nürnberg \ -- Leonard Cohen