On Thursday, December 17, 2020 3:23:44 PM CET Srinivas Pandruvada wrote: > 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;
Well, would something like the patch below work? --- drivers/cpufreq/intel_pstate.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -2207,9 +2207,9 @@ static void intel_pstate_update_perf_lim unsigned int policy_min, unsigned int policy_max) { - int max_freq = intel_pstate_get_max_freq(cpu); int32_t max_policy_perf, min_policy_perf; int max_state, turbo_max; + int max_freq; /* * HWP needs some special consideration, because on BDX the @@ -2223,6 +2223,7 @@ static void intel_pstate_update_perf_lim cpu->pstate.max_pstate : cpu->pstate.turbo_pstate; turbo_max = cpu->pstate.turbo_pstate; } + max_freq = max_state * cpu->pstate.scaling; max_policy_perf = max_state * policy_max / max_freq; if (policy_max == policy_min) { @@ -2325,9 +2326,18 @@ static void intel_pstate_adjust_policy_m static void intel_pstate_verify_cpu_policy(struct cpudata *cpu, struct cpufreq_policy_data *policy) { + int max_freq; + update_turbo_state(); - cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, - intel_pstate_get_max_freq(cpu)); + if (hwp_active) { + int max_state, turbo_max; + + intel_pstate_get_hwp_max(cpu->cpu, &turbo_max, &max_state); + max_freq = max_state * cpu->pstate.scaling; + } else { + max_freq = intel_pstate_get_max_freq(cpu); + } + cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, max_freq); intel_pstate_adjust_policy_max(cpu, policy); }