On Tue, 2011-10-11 at 10:51 +0200, Vincent Guittot wrote:
I have several goals. The 1st one is that I need to put more load on some cpus when I have packages with different cpu frequency.
That should be rather easy.
I also study if I can follow the real cpu frequency but it seems to be not so easy.
Why not?
I have noticed that the cpu_power is updated periodical except when we have a lot of newly_idle events.
We can certainly fix that.
Then, I have some use cases which have several running tasks but a low cpu load. In this case, the small tasks are spread on several cpu by the load_balance whereas they could be easily handled by one cpu without significant performance modification.
That shouldn't be done using cpu_power, we have sched_smt_power_savings and sched_mc_power_savings for stuff like that.
Although I would really like to kill all those different sched_*_power_savings knobs and reduce it to one.
If the cpu_power is higher than 1024, the cpu is no more seen out of capacity by the load_balance as soon as a short process is running and teh main result is that the small tasks will stay on the same cpu. This configuration is mainly usefull for ARM dual core system when we want to power gate one cpu. I use cyclictest to simulate such use case.
Yeah, but that's wrong.