Messages in this thread Patch in this message | | | From | "Rafael J. Wysocki" <> | Subject | [RFC][PATCH 2/2] cpufreq: intel_pstate: Implement the ->adjust_perf() callback | Date | Mon, 30 Nov 2020 19:37:55 +0100 |
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From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Make intel_pstate expose the ->adjust_perf() callback when it operates in the passive mode with HWP enabled which causes the schedutil governor to use that callback instead of ->fast_switch().
The minimum and target performance-level values passed by the governor to ->adjust_perf() are converted to HWP.REQ.MIN and HWP.REQ.DESIRED, respectively, which allows the processor to adjust its configuration to maximize energy-efficiency while providing sufficient capacity.
The "busy" argument of ->adjust_perf() is used to omit updates that are likely to cause performance to drop below the expected level.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> --- drivers/cpufreq/intel_pstate.c | 77 ++++++++++++++++++++++++++++++++++------- 1 file changed, 65 insertions(+), 12 deletions(-)
Index: linux-pm/drivers/cpufreq/intel_pstate.c =================================================================== --- linux-pm.orig/drivers/cpufreq/intel_pstate.c +++ linux-pm/drivers/cpufreq/intel_pstate.c @@ -2526,20 +2526,19 @@ static void intel_cpufreq_trace(struct c fp_toint(cpu->iowait_boost * 100)); } -static void intel_cpufreq_adjust_hwp(struct cpudata *cpu, u32 target_pstate, - bool strict, bool fast_switch) +static void intel_cpufreq_adjust_hwp(struct cpudata *cpu, u32 min, u32 max, + u32 desired, bool fast_switch) { u64 prev = READ_ONCE(cpu->hwp_req_cached), value = prev; value &= ~HWP_MIN_PERF(~0L); - value |= HWP_MIN_PERF(target_pstate); + value |= HWP_MIN_PERF(min); - /* - * The entire MSR needs to be updated in order to update the HWP min - * field in it, so opportunistically update the max too if needed. - */ value &= ~HWP_MAX_PERF(~0L); - value |= HWP_MAX_PERF(strict ? target_pstate : cpu->max_perf_ratio); + value |= HWP_MAX_PERF(max); + + value &= ~HWP_DESIRED_PERF(~0L); + value |= HWP_DESIRED_PERF(desired); if (value == prev) return; @@ -2569,11 +2568,15 @@ static int intel_cpufreq_update_pstate(s int old_pstate = cpu->pstate.current_pstate; target_pstate = intel_pstate_prepare_request(cpu, target_pstate); - if (hwp_active) - intel_cpufreq_adjust_hwp(cpu, target_pstate, - policy->strict_target, fast_switch); - else if (target_pstate != old_pstate) + if (hwp_active) { + int max_pstate = policy->strict_target ? + target_pstate : cpu->max_perf_ratio; + + intel_cpufreq_adjust_hwp(cpu, target_pstate, max_pstate, 0, + fast_switch); + } else if (target_pstate != old_pstate) { intel_cpufreq_adjust_perf_ctl(cpu, target_pstate, fast_switch); + } cpu->pstate.current_pstate = target_pstate; @@ -2634,6 +2637,54 @@ static unsigned int intel_cpufreq_fast_s return target_pstate * cpu->pstate.scaling; } +static void intel_cpufreq_adjust_perf(unsigned int cpunum, bool busy, + unsigned long min_perf, + unsigned long target_perf, + unsigned long capacity) +{ + struct cpudata *cpu = all_cpu_data[cpunum]; + int old_pstate = cpu->pstate.current_pstate; + int cap_pstate, min_pstate, max_pstate, target_pstate; + + update_turbo_state(); + cap_pstate = global.turbo_disabled ? cpu->pstate.max_pstate : + cpu->pstate.turbo_pstate; + + /* Optimization: Avoid unnecessary divisions. */ + + target_pstate = cap_pstate; + if (target_perf < capacity) { + target_pstate = DIV_ROUND_UP(cap_pstate * target_perf, capacity); + /* + * Do not reduce the target P-state if the CPU has been busy + * recently, as the reduction is likely to be premature then. + */ + if (target_pstate < old_pstate && busy) + target_pstate = old_pstate; + } + + min_pstate = cap_pstate; + if (min_perf < capacity) + min_pstate = DIV_ROUND_UP(cap_pstate * min_perf, capacity); + + if (min_pstate < cpu->pstate.min_pstate) + min_pstate = cpu->pstate.min_pstate; + + if (min_pstate < cpu->min_perf_ratio) + min_pstate = cpu->min_perf_ratio; + + max_pstate = min(cap_pstate, cpu->max_perf_ratio); + if (max_pstate < min_pstate) + max_pstate = min_pstate; + + target_pstate = clamp_t(int, target_pstate, min_pstate, max_pstate); + + intel_cpufreq_adjust_hwp(cpu, min_pstate, max_pstate, target_pstate, true); + + cpu->pstate.current_pstate = target_pstate; + intel_cpufreq_trace(cpu, INTEL_PSTATE_TRACE_FAST_SWITCH, old_pstate); +} + static int intel_cpufreq_cpu_init(struct cpufreq_policy *policy) { int max_state, turbo_max, min_freq, max_freq, ret; @@ -3032,6 +3083,8 @@ static int __init intel_pstate_init(void intel_pstate.attr = hwp_cpufreq_attrs; intel_cpufreq.attr = hwp_cpufreq_attrs; intel_cpufreq.flags |= CPUFREQ_NEED_UPDATE_LIMITS; + intel_cpufreq.fast_switch = NULL; + intel_cpufreq.adjust_perf = intel_cpufreq_adjust_perf; if (!default_driver) default_driver = &intel_pstate;
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