On Tue, 2015-07-21 at 13:25 +0300, Konstantin Khlebnikov wrote: > On 21.07.2015 00:08, Srinivas Pandruvada wrote: > > On Fri, 2015-07-17 at 07:36 +0300, Konstantin Khlebnikov wrote: > >> On Fri, Jul 17, 2015 at 1:08 AM, Srinivas Pandruvada > >> <srinivas.pandruvada@xxxxxxxxxxxxxxx> wrote: > >>> On Thu, 2015-07-16 at 21:17 +0300, Konstantin Khlebnikov wrote: > >>>> IPMI can control CPU P-states remotely: configuration is reported via > >>>> common ACPI interface (_PPC/_PSS/etc). This patch adds required minimal > >>>> support in intel_pstate to receive and use these P-state limits. > >>>> > >>>> * ignore limit of top state in _PPC: it lower than turbo boost frequency > >>>> * register intel_pstate in acpi-processor to get states from _PSS > >>>> * link acpi_processor_get_bios_limit: this adds attribute "bios_limit" > >>>> > >>>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> > >>>> --- > >>>> drivers/acpi/processor_perflib.c | 3 +- > >>>> drivers/cpufreq/intel_pstate.c | 57 ++++++++++++++++++++++++++++++++++++++ > >>>> 2 files changed, 59 insertions(+), 1 deletion(-) > >>>> > >>>> diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c > >>>> index cfc8aba72f86..781e328c9d5f 100644 > >>>> --- a/drivers/acpi/processor_perflib.c > >>>> +++ b/drivers/acpi/processor_perflib.c > >>>> @@ -98,7 +98,8 @@ static int acpi_processor_ppc_notifier(struct notifier_block *nb, > >>>> > >>>> ppc = (unsigned int)pr->performance_platform_limit; > >>>> > >>>> - if (ppc >= pr->performance->state_count) > >>>> + /* Ignore limit of top state: it lower than turbo boost frequency */ > >>>> + if (!ppc || ppc >= pr->performance->state_count) > >>> Why? Isn't the previous check enough? > >> > >> Zero _PPC state must be top performance state but as I see frequency in > >> _PSS is lower than maximum possible turbo frequency. So, in this case > >> intel_pstate cannnot get "100%" for max bound even it there is no limit set. > >> > >> For example: I saw _PSS[0] = 2601 Mhz, PSS[1] = 2600 Mhz while turbo > >> state is 3400 Mhz. > >> > > Have you tested dynamic _PPC modification with acpi cpufreq with this > > change (after boot)? Suppose _PPC is changed from 3 to 0, then > > cpufreq_verify_within_limits will not be called to change to new max > > turbo performance state. > > > > I haven't checked that but as I see acpi_processor_ppc_notifier() > can only reduce maximum frequency. So, there should be no problem > in this case. No, it can also be used in both ways. Once reduced, it can increase as well. _PPC can be dynamically modified by BIOS to reduce and also to increase. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
