On Thu, 2020-12-17 at 06:19 -0800, Srinivas Pandruvada wrote: > On Thu, 2020-12-17 at 14:58 +0100, Rafael J. Wysocki wrote: > > On Thu, Dec 17, 2020 at 11:44 AM Srinivas Pandruvada > > <srinivas.pandruv...@linux.intel.com> wrote: > > > > > > This change tries to address an issue, when BIOS disabled turbo > > > but HWP_CAP guaranteed is changed later and user space wants to > > > take > > > advantage of this increased guaranteed performance. > > > > > > The HWP_CAP.GUARANTEED value is not a static value. It can be > > > changed > > > by some out of band agent or during Intel Speed Select > > > performance > > > level change. The HWP_CAP.MAX still shows max possible > > > performance > > > when > > > BIOS disabled turbo. So guaranteed can still change as long as > > > this > > > is > > > same or below HWP_CAP.MAX. > > > > > > When guaranteed is changed, the sysfs base_frequency attributes > > > shows > > > the latest guaranteed frequency. This attribute can be used by > > > user > > > space software to update scaling min/max frequency. > > > > > > Currently the setpolicy callback already uses the latest HWP_CAP > > > values when setting HWP_REQ. But the verify callback will still > > > restrict > > > the user settings to the to old guaranteed value. So if the > > > guaranteed > > > is increased, user space can't take advantage of it. > > > > > > To solve this similar to setpolicy callback, read the latest > > > HWP_CAP > > > values and use it to restrict the maximum setting. This is done > > > by > > > calling intel_pstate_get_hwp_max(), which already accounts for > > > user > > > and BIOS turbo disable to get the current max performance. > > > > > > This issue is side effect of fixing the issue of scaling > > > frequency > > > limits by the > > > 'commit eacc9c5a927e ("cpufreq: intel_pstate: > > > Fix intel_pstate_get_hwp_max() for turbo disabled")' > > > The fix resulted in correct setting of reduced scaling > > > frequencies, > > > but this resulted in capping HWP.REQ to HWP_CAP.GUARANTEED in > > > this > > > case. > > > > > > Cc: 5.8+ <sta...@vger.kernel.org> # 5.8+ > > > Signed-off-by: Srinivas Pandruvada < > > > srinivas.pandruv...@linux.intel.com> > > > --- > > > drivers/cpufreq/intel_pstate.c | 6 ++++++ > > > 1 file changed, 6 insertions(+) > > > > > > diff --git a/drivers/cpufreq/intel_pstate.c > > > b/drivers/cpufreq/intel_pstate.c > > > index 2a4db856222f..7081d1edb22b 100644 > > > --- a/drivers/cpufreq/intel_pstate.c > > > +++ b/drivers/cpufreq/intel_pstate.c > > > @@ -2199,6 +2199,12 @@ static void > > > intel_pstate_clear_update_util_hook(unsigned int cpu) > > > > > > static int intel_pstate_get_max_freq(struct cpudata *cpu) > > > { > > > + if (hwp_active) { > > > + int turbo_max, max_state; > > > + > > > + intel_pstate_get_hwp_max(cpu->cpu, &turbo_max, > > > &max_state); > > > > This would cause intel_pstate_get_hwp_max() to be called twice in > > intel_pstate_update_perf_limits() which is not perfect. > > We can optimize by using cached value. > > > diff --git a/drivers/cpufreq/intel_pstate.c > b/drivers/cpufreq/intel_pstate.c > index 7081d1edb22b..d345c9ef240c 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -2223,7 +2223,11 @@ static void > intel_pstate_update_perf_limits(struct cpudata *cpu, > * rather than pure ratios. > */ > if (hwp_active) { > - intel_pstate_get_hwp_max(cpu->cpu, &turbo_max, > &max_state); > + if (global.no_turbo || global.turbo_disabled) > + max_state = HWP_GUARANTEED_PERF(cpu- > > hwp_cap_cached); > + else > + max_state = HWP_HIGHEST_PERF(cpu- > > hwp_cap_cached); Can use ternary operator instead of if..else. to further simplify.
> + turbo_max = HWP_HIGHEST_PERF(cpu->hwp_cached); > } else { > max_state = global.no_turbo || global.turbo_disabled > ? > cpu->pstate.max_pstate : cpu- > > pstate.turbo_pstate; > > > Thanks, > Srinivas > > > > > > > + return max_state * cpu->pstate.scaling; > > > + } > > > return global.turbo_disabled || global.no_turbo ? > > > cpu->pstate.max_freq : cpu- > > > > pstate.turbo_freq; > > > } > > > -- >