On 21/11/16 11:19, Peter Zijlstra wrote:
On Mon, Nov 21, 2016 at 03:38:05PM +0530, Viresh Kumar wrote:
On 17-11-16, 10:48, Viresh Kumar wrote:
[...]
(Background story for others from my discussion with Rafael on IRC: Rafael proposed that instead of this patch we can add down_rate_limit_delta_us (>0 =) which can be added to rate_limit_us (rate limit while increasing freq) to find the rate limit to be used in the downward direction. And I raised the point that it looks much neater to have separate up and down rate_limit_us. I also said that people may have a valid case where they want to keep down_rate_limit lower than up_rate_limit and Rafael wasn't fully sure of any such cases).
Urgh...
So no tunables and rate limits here at all please.
During LPC we discussed the rampup and decay issues and decided that we should very much first address them by playing with the PELT stuff. Morton was going to play with capping the decay on the util signal. This should greatly improve the ramp-up scenario and cure some other wobbles.
The decay can be set by changing the over-all pelt decay, if so desired.
Do you mean we might want to change the decay (make it different from ramp-up) once for all, or maybe we make it tunable so that we can address different power/perf requirements?
Also, there was the idea of; once the above ideas have all been explored; tying the freq ram rate to the power curve.
Yep. That's an interesting one to look at, but it might require some time.
So NAK on everything tunable here.