On Tue, Jul 17, 2018 at 11:23:25AM +0200, Rafael J. Wysocki wrote: > On Tue, Jul 17, 2018 at 11:11 AM, Andreas Herrmann <aherrm...@suse.com> wrote: > > On Tue, Jul 17, 2018 at 11:06:29AM +0200, Rafael J. Wysocki wrote: > >> On Tue, Jul 17, 2018 at 10:50 AM, Andreas Herrmann <aherrm...@suse.com> > >> wrote: > >> > >> [cut] > >> > >> > > >> > On balance before this commit users could use pcc-cpufreq but had > >> > already suboptimal performance (compared to say intel_pstate driver > >> > which can be used changing BIOS options). > >> > >> BTW, I wonder why you need to change the BIOS options for intel_pstate to > >> load. > > > > I think this is because of (in intel_pstate_init()): > > > > /* > > * The Intel pstate driver will be ignored if the platform > > * firmware has its own power management modes. > > */ > > if (intel_pstate_platform_pwr_mgmt_exists()) > > return -ENODEV; > > > > OK, because of the "Proliant" entry, right? > > So it looks like we have an issue there. We find the entry and we > look for _PSS. It is not there, so we assume that the firmware is > expected to control performance, which is not the case. It looks like > we also should look for the presence of the PCC interface in there. > > I can provide a patch for that, will you be able to test it?
Yes, I can test it. > >> It should be initialized before pcc-cpufreq (according to their > >> respective initcall levels), so in theory intel_pstate should be used > >> by default on the affected systems anyway. > > > >> What BIOS settings need to be changed for that? > > > > Already answered in other mail. > > Indeed. Andreas