A Power Saving Schema For The Linux Kernel Scheduler

[phoronix]

Phoronix: A Power Saving Schema For The Linux Kernel Scheduler

An Intel engineer has proposed introducing a power saving schema for CFS, the Linux kernel's default scheduler. Code hasn't been presented yet, but there's lots of discussion about this topic to improve the power efficiency of the Linux kernel scheduler...

http://www.phoronix.com/vr.php?view=MTE2MjE

[nej_simon]

Intel's work here, if it's merged, will benefit a lot of downstream projects that uses the Linux kernel such as Andorid, tizen, Open WebOS, meego (or whatever it's called now) etc. This is the beauty of open source, developers of products will indirectly help competeing products by contributing upstream.

[mayankleoboy1]

but doing this is against the Turbo boost that Intel have implemented in their CPU's. So this will cause performance degradation.

[stqn]

This seems to be in conflict with the sched_mc_power_savings and sched_smt_power_savings parameters that (from what I gathered) tell the kernel to group processes on a single core in order to put the others to sleep and reduce power consumption…?

[dalingrin]

but doing this is against the Turbo boost that Intel have implemented in their CPU's. So this will cause performance degradation.

I'm sure this is primarily targeting power constrained platforms like Android. Remember that not all Intel CPUs have turbo and additionally I would think this power saving schema would be optional like many other parameters in CFS.

This seems to be in conflict with the sched_mc_power_savings and sched_smt_power_savings parameters that (from what I gathered) tell the kernel to group processes on a single core in order to put the others to sleep and reduce power consumption…?

In a world with DVFS I don't think keeping one core at 100% load is as efficient as two cores at even 75% load. Remember that Power = Voltage^2 / Resistance. Keeping voltage lower can make a huge difference on power draw even if it is at the cost of keeping additional cores active.