Re: [PATCH] cpufreq: schedutil: Don't skip freq update when limits change

[Viresh Kumar]

On 02-08-19, 11:11, Rafael J. Wysocki wrote:
> On Friday, August 2, 2019 5:48:19 AM CEST Viresh Kumar wrote:
> > On 01-08-19, 10:57, Doug Smythies wrote:
> > > Disagree.
> > > All I did was use a flag where it used to be set to UNIT_MAX, to basically
> > > implement the same thing.
> > 
> > And the earlier code wasn't fully correct as well, that's why we tried
> > to fix it earlier.
> 
> Your argument seems to be "There was an earlier problem related to this, which
> was fixed, so it is fragile and I'd rather avoid it".  Still, you are claiming that the
> code was in fact incorrect and you are not giving convincing arguments to
> support that.
> 
> > So introducing the UINT_MAX thing again would be
> > wrong, even if it fixes the problem for you.
> 
> Would it be wrong, because it would reintroduce the fragile code, or would it
> be wrong, because it would re-introduce a bug?  What bug if so?

There will be two issues here if that patch is reintroduced:

- It will cause the BUG to reappear, which was fixed by the earlier
  commit. The commit log of ecd28842912 explains the bug in detail.

- And overriding next_freq as a flag will make the code fragile and we
  may have similar bugs coming up.

But yeah, lets continue discussion on the intel-pstate patch now.

-- 
viresh