On Mon, Nov 21, 2016 at 02:37:27PM +0000, Juri Lelli wrote:

On 21/11/16 15:17, Peter Zijlstra wrote:

quoted

Not sure I follow. So by limiting decay to the task value, the moment we
add it back to the accumulated signal (wakeup), the accumulated signal
jumps up quickly and ramp-up is achieved.

This is true, but it seems that this potentially spiky behaviour
(which in general depends on tasks composition and periodicity) might
affect power savings (as in you don't generally want to switch between
high and low freqs too often). So that's why I was just thinking that
some sort of smoothing applied to the signal schedutil uses might help.

Hurm.. so during LPC it was said that fast ramp-up was desired. Note
that we'll not ramp down this fast, the accumulated signal will decay
slowly as per blocked-load PELT rules. So only ramp-up is spiky, but
that is what was desired AFAIU.