* Benjamin Herrenschmidt benh@kernel.crashing.org wrote:
On Wed, 2012-02-08 at 15:23 -0500, Dave Jones wrote:
I think the biggest mistake we ever made with cpufreq was making it so configurable. If we redesign it, just say no to plugin governors, and yes to a lot fewer sysfs knobs.
So, provide mechanism to kill off all the governors, and there's a migration path from what we have now to something that just works in a lot more cases, while remaining configurable enough for the corner-cases.
On the other hand, the need for schedulable contxts may not necessarily go away.
We will support it, but the *sane* hw solution is where frequency transitions can be done atomically. Most workloads change their characteristics very quickly, and so does their power management profile change.
The user-space driven policy model failed for that reason: it was *way* too slow in reacting) - and slow hardware transitions suck for a similar reason as well.
We accomodate all hardware as well as we can, but we *design* for proper hardware. So Peter is right, this should be done properly.
Thanks,
Ingo