Hi Rafael, On Wed, Jan 03, 2018 at 11:47:58PM +1100, Balbir Singh wrote: > On Wed, Jan 3, 2018 at 11:07 PM, Rafael J. Wysocki <r...@rjwysocki.net> wrote: > > On Monday, December 18, 2017 9:38:20 AM CET Gautham R Shenoy wrote: > >> Hi Balbir, > >> > >> On Sun, Dec 17, 2017 at 02:15:25PM +1100, Balbir Singh wrote: > >> > On Wed, Dec 13, 2017 at 5:57 PM, Gautham R. Shenoy > >> > <e...@linux.vnet.ibm.com> wrote: > >> > > From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com> > >> > > > >> > > The code in powernv-cpufreq, makes the following two assumptions which > >> > > are not guaranteed by the device-tree bindings: > >> > > > >> > > 1) Pstate ids are continguous: This is used in pstate_to_idx() to > >> > > obtain the reverse map from a pstate to it's corresponding > >> > > entry into the cpufreq frequency table. > >> > > > >> > > 2) Every Pstate should always lie between the max and the min > >> > > pstates that are explicitly reported in the device tree: This > >> > > is used to determine whether a pstate reported by the PMSR is > >> > > out of bounds. > >> > > > >> > > Both these assumptions are unwarranted and can change on future > >> > > platforms. > >> > > >> > While this is a good thing, I wonder if it is worth the complexity. > >> > Pstates > >> > are contiguous because they define transitions in incremental value > >> > of change in frequency and I can't see how this can be broken in the > >> > future? > >> > >> In the future, we can have the OPAL firmware give us a smaller set of > >> pstates instead of expose every one of them. As it stands today, for > >> most of the workloads, we will need at best 20-30 pstates and not > >> beyond that. > > > > I'm not sure about the status here. > > > > Is this good to go as is or is it going to be updated? > > > > I have no major objections, except some of the added complexity, but > Gautham makes a point that this is refactoring for the future
I have tested this across POWER8 and POWER9. The additional complexity introduced by the second patch is required for the future when we are going to reduce the number of pstates. > > Balbir Singh. > -- Thanks and Regards gautham.
