| Message ID | 8115130.Fhkpr82c7G@aspire.rjw.lan (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Tue, 2018-07-17 at 18:13 +0200, Rafael J. Wysocki wrote: > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > Currently, intel_pstate doesn't load if _PSS is not present on > HP Proliant systems, because it expects the firmware to take over > CPU performance scaling in that case. However, if ACPI PCCH is > present, the firmware expects the kernel to use it for CPU > performance scaling and the pcc-cpufreq driver is loaded for that. > > Unfortunately, the firmware interface used by that driver is not > scalable for fundamental reasons, so pcc-cpufreq is way suboptimal > on systems with more than just a few CPUs. In fact, it is better to > avoid using it at all. > > For this reason, modify intel_pstate to look for ACPI PCCH if _PSS > is not present and load if it is there. > > Fixes: fbbcdc0744da (intel_pstate: skip the driver if ACPI has power > mgmt option) > Reported-by: Andreas Herrmann <aherrmann@suse.com> > Tested-by: Andreas Herrmann <aherrmann@suse.com> > Reviewed-by: Andreas Herrmann <aherrmann@suse.com> > Cc: 4.17+ <stable@vger.kernel.org> # 4.17+ > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> But do we need a change as done by the following commit in in pcc- cpufreq.c? " commit 8a61e12e84597b5f8155ac91b44dea866ccfaac2 Author: Yinghai Lu <yinghai@kernel.org> Date: Fri Sep 20 10:43:56 2013 -0700 acpi-cpufreq: skip loading acpi_cpufreq after intel_pstate " Thanks, Srinivas > --- > drivers/cpufreq/intel_pstate.c | 17 ++++++++++++++++- > 1 file changed, 16 insertions(+), 1 deletion(-) > > Index: linux-pm/drivers/cpufreq/intel_pstate.c > =================================================================== > --- linux-pm.orig/drivers/cpufreq/intel_pstate.c > +++ linux-pm/drivers/cpufreq/intel_pstate.c > @@ -2391,6 +2391,18 @@ static bool __init intel_pstate_no_acpi_ > return true; > } > > +static bool __init intel_pstate_no_acpi_pcch(void) > +{ > + acpi_status status; > + acpi_handle handle; > + > + status = acpi_get_handle(NULL, "\\_SB", &handle); > + if (ACPI_FAILURE(status)) > + return true; > + > + return !acpi_has_method(handle, "PCCH"); > +} > + > static bool __init intel_pstate_has_acpi_ppc(void) > { > int i; > @@ -2450,7 +2462,10 @@ static bool __init intel_pstate_platform > > switch (plat_info[idx].data) { > case PSS: > - return intel_pstate_no_acpi_pss(); > + if (!intel_pstate_no_acpi_pss()) > + return false; > + > + return intel_pstate_no_acpi_pcch(); > case PPC: > return intel_pstate_has_acpi_ppc() && !force_load; > } >
On Tue, Jul 17, 2018 at 7:23 PM, Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote: > On Tue, 2018-07-17 at 18:13 +0200, Rafael J. Wysocki wrote: >> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >> >> Currently, intel_pstate doesn't load if _PSS is not present on >> HP Proliant systems, because it expects the firmware to take over >> CPU performance scaling in that case. However, if ACPI PCCH is >> present, the firmware expects the kernel to use it for CPU >> performance scaling and the pcc-cpufreq driver is loaded for that. >> >> Unfortunately, the firmware interface used by that driver is not >> scalable for fundamental reasons, so pcc-cpufreq is way suboptimal >> on systems with more than just a few CPUs. In fact, it is better to >> avoid using it at all. >> >> For this reason, modify intel_pstate to look for ACPI PCCH if _PSS >> is not present and load if it is there. >> >> Fixes: fbbcdc0744da (intel_pstate: skip the driver if ACPI has power >> mgmt option) >> Reported-by: Andreas Herrmann <aherrmann@suse.com> >> Tested-by: Andreas Herrmann <aherrmann@suse.com> >> Reviewed-by: Andreas Herrmann <aherrmann@suse.com> >> Cc: 4.17+ <stable@vger.kernel.org> # 4.17+ >> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> > > But do we need a change as done by the following commit in in pcc- > cpufreq.c? > > " > commit 8a61e12e84597b5f8155ac91b44dea866ccfaac2 > Author: Yinghai Lu <yinghai@kernel.org> > Date: Fri Sep 20 10:43:56 2013 -0700 > > acpi-cpufreq: skip loading acpi_cpufreq after intel_pstate > > " Quite likely yes, good point! >> --- >> drivers/cpufreq/intel_pstate.c | 17 ++++++++++++++++- >> 1 file changed, 16 insertions(+), 1 deletion(-) >> >> Index: linux-pm/drivers/cpufreq/intel_pstate.c >> =================================================================== >> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c >> +++ linux-pm/drivers/cpufreq/intel_pstate.c >> @@ -2391,6 +2391,18 @@ static bool __init intel_pstate_no_acpi_ >> return true; >> } >> >> +static bool __init intel_pstate_no_acpi_pcch(void) >> +{ >> + acpi_status status; >> + acpi_handle handle; >> + >> + status = acpi_get_handle(NULL, "\\_SB", &handle); >> + if (ACPI_FAILURE(status)) >> + return true; >> + >> + return !acpi_has_method(handle, "PCCH"); >> +} >> + >> static bool __init intel_pstate_has_acpi_ppc(void) >> { >> int i; >> @@ -2450,7 +2462,10 @@ static bool __init intel_pstate_platform >> >> switch (plat_info[idx].data) { >> case PSS: >> - return intel_pstate_no_acpi_pss(); >> + if (!intel_pstate_no_acpi_pss()) >> + return false; >> + >> + return intel_pstate_no_acpi_pcch(); >> case PPC: >> return intel_pstate_has_acpi_ppc() && !force_load; >> } >>
Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -2391,6 +2391,18 @@ static bool __init intel_pstate_no_acpi_ return true; } +static bool __init intel_pstate_no_acpi_pcch(void) +{ + acpi_status status; + acpi_handle handle; + + status = acpi_get_handle(NULL, "\\_SB", &handle); + if (ACPI_FAILURE(status)) + return true; + + return !acpi_has_method(handle, "PCCH"); +} + static bool __init intel_pstate_has_acpi_ppc(void) { int i; @@ -2450,7 +2462,10 @@ static bool __init intel_pstate_platform switch (plat_info[idx].data) { case PSS: - return intel_pstate_no_acpi_pss(); + if (!intel_pstate_no_acpi_pss()) + return false; + + return intel_pstate_no_acpi_pcch(); case PPC: return intel_pstate_has_acpi_ppc() && !force_load; }