Re: [PATCH] cpufreq: schedutil: add up/down frequency transition rate limits

[Wanpeng Li]

2016-11-21 20:26 GMT+08:00 Peter Zijlstra <peterz@xxxxxxxxxxxxx>:
> On Mon, Nov 21, 2016 at 12:14:32PM +0000, Juri Lelli wrote:
>> On 21/11/16 11:19, Peter Zijlstra wrote:
>
>> > 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?
>
> So the limited decay would be the dominant factor in ramp-up time,
> leaving the regular PELT period the dominant factor for ramp-down.
>
> (Note that the decay limit would only be applied on the per-task signal,
> not the accumulated signal.)

What's the meaning of "signal" in this thread?

Regards,
Wanpeng Li