cpufreq: intel_pstate: Generic governors support
There may be reasons to use generic cpufreq governors (eg. schedutil) on Intel platforms instead of the intel_pstate driver's internal governor. However, that currently can only be done by disabling intel_pstate altogether and using the acpi-cpufreq driver instead of it, which is subject to limitations. First of all, acpi-cpufreq only works on systems where the _PSS object is present in the ACPI tables for all logical CPUs. Second, on those systems acpi-cpufreq will only use frequencies listed by _PSS which may be suboptimal. In particular, by convention, the whole turbo range is represented in _PSS as a single P-state and the frequency assigned to it is greater by 1 MHz than the greatest non-turbo frequency listed by _PSS. That may confuse governors to use turbo frequencies less frequently which may lead to suboptimal performance. For this reason, make it possible to use the intel_pstate driver with generic cpufreq governors as a "normal" cpufreq driver. That mode is enforced by adding intel_pstate=passive to the kernel command line and cannot be disabled at run time. In that mode, intel_pstate provides a cpufreq driver interface including the ->target() and ->fast_switch() callbacks and is listed in scaling_driver as "intel_cpufreq". Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Tested-by: Doug Smythies <dsmythies@telus.net>
This commit is contained in:
parent
d0ea59e188
commit
001c76f05b
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@ -1760,6 +1760,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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disable
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Do not enable intel_pstate as the default
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scaling driver for the supported processors
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passive
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Use intel_pstate as a scaling driver, but configure it
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to work with generic cpufreq governors (instead of
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enabling its internal governor). This mode cannot be
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used along with the hardware-managed P-states (HWP)
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feature.
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force
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Enable intel_pstate on systems that prohibit it by default
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in favor of acpi-cpufreq. Forcing the intel_pstate driver
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@ -37,6 +37,8 @@
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#include <asm/cpufeature.h>
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#include <asm/intel-family.h>
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#define INTEL_CPUFREQ_TRANSITION_LATENCY 20000
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#define ATOM_RATIOS 0x66a
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#define ATOM_VIDS 0x66b
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#define ATOM_TURBO_RATIOS 0x66c
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@ -122,6 +124,8 @@ struct sample {
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* @scaling: Scaling factor to convert frequency to cpufreq
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* frequency units
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* @turbo_pstate: Max Turbo P state possible for this platform
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* @max_freq: @max_pstate frequency in cpufreq units
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* @turbo_freq: @turbo_pstate frequency in cpufreq units
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*
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* Stores the per cpu model P state limits and current P state.
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*/
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@ -132,6 +136,8 @@ struct pstate_data {
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int max_pstate_physical;
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int scaling;
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int turbo_pstate;
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unsigned int max_freq;
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unsigned int turbo_freq;
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};
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/**
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@ -470,7 +476,7 @@ static void intel_pstate_init_acpi_perf_limits(struct cpufreq_policy *policy)
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{
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}
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static void intel_pstate_exit_perf_limits(struct cpufreq_policy *policy)
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static inline int intel_pstate_exit_perf_limits(struct cpufreq_policy *policy)
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{
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}
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#endif
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@ -1225,6 +1231,8 @@ static void intel_pstate_get_cpu_pstates(struct cpudata *cpu)
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cpu->pstate.max_pstate_physical = pstate_funcs.get_max_physical();
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cpu->pstate.turbo_pstate = pstate_funcs.get_turbo();
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cpu->pstate.scaling = pstate_funcs.get_scaling();
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cpu->pstate.max_freq = cpu->pstate.max_pstate * cpu->pstate.scaling;
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cpu->pstate.turbo_freq = cpu->pstate.turbo_pstate * cpu->pstate.scaling;
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if (pstate_funcs.get_vid)
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pstate_funcs.get_vid(cpu);
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@ -1363,15 +1371,19 @@ static inline int32_t get_target_pstate_use_performance(struct cpudata *cpu)
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return cpu->pstate.current_pstate - pid_calc(&cpu->pid, perf_scaled);
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}
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static inline void intel_pstate_update_pstate(struct cpudata *cpu, int pstate)
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static int intel_pstate_prepare_request(struct cpudata *cpu, int pstate)
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{
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int max_perf, min_perf;
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update_turbo_state();
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intel_pstate_get_min_max(cpu, &min_perf, &max_perf);
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pstate = clamp_t(int, pstate, min_perf, max_perf);
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trace_cpu_frequency(pstate * cpu->pstate.scaling, cpu->cpu);
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return pstate;
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}
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static void intel_pstate_update_pstate(struct cpudata *cpu, int pstate)
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{
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pstate = intel_pstate_prepare_request(cpu, pstate);
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if (pstate == cpu->pstate.current_pstate)
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return;
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@ -1389,6 +1401,8 @@ static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu)
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target_pstate = cpu->policy == CPUFREQ_POLICY_PERFORMANCE ?
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cpu->pstate.turbo_pstate : pstate_funcs.get_target_pstate(cpu);
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update_turbo_state();
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intel_pstate_update_pstate(cpu, target_pstate);
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sample = &cpu->sample;
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@ -1670,22 +1684,30 @@ static int intel_pstate_verify_policy(struct cpufreq_policy *policy)
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return 0;
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}
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static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
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static void intel_cpufreq_stop_cpu(struct cpufreq_policy *policy)
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{
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int cpu_num = policy->cpu;
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struct cpudata *cpu = all_cpu_data[cpu_num];
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pr_debug("CPU %d exiting\n", cpu_num);
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intel_pstate_clear_update_util_hook(cpu_num);
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if (hwp_active)
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return;
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intel_pstate_set_min_pstate(cpu);
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intel_pstate_set_min_pstate(all_cpu_data[policy->cpu]);
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}
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static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
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static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
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{
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pr_debug("CPU %d exiting\n", policy->cpu);
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intel_pstate_clear_update_util_hook(policy->cpu);
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if (!hwp_active)
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intel_cpufreq_stop_cpu(policy);
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}
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static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
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{
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intel_pstate_exit_perf_limits(policy);
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policy->fast_switch_possible = false;
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return 0;
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}
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static int __intel_pstate_cpu_init(struct cpufreq_policy *policy)
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{
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struct cpudata *cpu;
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int rc;
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@ -1696,11 +1718,6 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
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cpu = all_cpu_data[policy->cpu];
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if (limits->min_perf_pct == 100 && limits->max_perf_pct == 100)
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policy->policy = CPUFREQ_POLICY_PERFORMANCE;
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else
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policy->policy = CPUFREQ_POLICY_POWERSAVE;
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/*
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* We need sane value in the cpu->perf_limits, so inherit from global
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* perf_limits limits, which are seeded with values based on the
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policy->cpuinfo.max_freq *= cpu->pstate.scaling;
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intel_pstate_init_acpi_perf_limits(policy);
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policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
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cpumask_set_cpu(policy->cpu, policy->cpus);
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policy->fast_switch_possible = true;
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return 0;
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}
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static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
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static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
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{
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intel_pstate_exit_perf_limits(policy);
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int ret = __intel_pstate_cpu_init(policy);
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if (ret)
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return ret;
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policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
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if (limits->min_perf_pct == 100 && limits->max_perf_pct == 100)
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policy->policy = CPUFREQ_POLICY_PERFORMANCE;
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else
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policy->policy = CPUFREQ_POLICY_POWERSAVE;
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return 0;
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}
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static struct cpufreq_driver intel_pstate_driver = {
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static struct cpufreq_driver intel_pstate = {
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.flags = CPUFREQ_CONST_LOOPS,
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.verify = intel_pstate_verify_policy,
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.setpolicy = intel_pstate_set_policy,
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.name = "intel_pstate",
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};
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static int intel_cpufreq_verify_policy(struct cpufreq_policy *policy)
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{
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struct cpudata *cpu = all_cpu_data[policy->cpu];
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struct perf_limits *perf_limits = limits;
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update_turbo_state();
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policy->cpuinfo.max_freq = limits->turbo_disabled ?
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cpu->pstate.max_freq : cpu->pstate.turbo_freq;
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cpufreq_verify_within_cpu_limits(policy);
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if (per_cpu_limits)
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perf_limits = cpu->perf_limits;
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intel_pstate_update_perf_limits(policy, perf_limits);
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return 0;
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}
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static unsigned int intel_cpufreq_turbo_update(struct cpudata *cpu,
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struct cpufreq_policy *policy,
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unsigned int target_freq)
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{
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unsigned int max_freq;
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update_turbo_state();
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max_freq = limits->no_turbo || limits->turbo_disabled ?
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cpu->pstate.max_freq : cpu->pstate.turbo_freq;
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policy->cpuinfo.max_freq = max_freq;
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if (policy->max > max_freq)
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policy->max = max_freq;
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if (target_freq > max_freq)
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target_freq = max_freq;
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return target_freq;
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}
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static int intel_cpufreq_target(struct cpufreq_policy *policy,
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unsigned int target_freq,
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unsigned int relation)
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{
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struct cpudata *cpu = all_cpu_data[policy->cpu];
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struct cpufreq_freqs freqs;
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int target_pstate;
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freqs.old = policy->cur;
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freqs.new = intel_cpufreq_turbo_update(cpu, policy, target_freq);
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cpufreq_freq_transition_begin(policy, &freqs);
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switch (relation) {
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case CPUFREQ_RELATION_L:
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target_pstate = DIV_ROUND_UP(freqs.new, cpu->pstate.scaling);
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break;
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case CPUFREQ_RELATION_H:
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target_pstate = freqs.new / cpu->pstate.scaling;
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break;
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default:
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target_pstate = DIV_ROUND_CLOSEST(freqs.new, cpu->pstate.scaling);
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break;
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}
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target_pstate = intel_pstate_prepare_request(cpu, target_pstate);
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if (target_pstate != cpu->pstate.current_pstate) {
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cpu->pstate.current_pstate = target_pstate;
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wrmsrl_on_cpu(policy->cpu, MSR_IA32_PERF_CTL,
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pstate_funcs.get_val(cpu, target_pstate));
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}
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cpufreq_freq_transition_end(policy, &freqs, false);
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return 0;
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}
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static unsigned int intel_cpufreq_fast_switch(struct cpufreq_policy *policy,
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unsigned int target_freq)
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{
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struct cpudata *cpu = all_cpu_data[policy->cpu];
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int target_pstate;
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target_freq = intel_cpufreq_turbo_update(cpu, policy, target_freq);
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target_pstate = DIV_ROUND_UP(target_freq, cpu->pstate.scaling);
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intel_pstate_update_pstate(cpu, target_pstate);
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return target_freq;
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}
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static int intel_cpufreq_cpu_init(struct cpufreq_policy *policy)
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{
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int ret = __intel_pstate_cpu_init(policy);
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if (ret)
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return ret;
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policy->cpuinfo.transition_latency = INTEL_CPUFREQ_TRANSITION_LATENCY;
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/* This reflects the intel_pstate_get_cpu_pstates() setting. */
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policy->cur = policy->cpuinfo.min_freq;
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return 0;
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}
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static struct cpufreq_driver intel_cpufreq = {
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.flags = CPUFREQ_CONST_LOOPS,
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.verify = intel_cpufreq_verify_policy,
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.target = intel_cpufreq_target,
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.fast_switch = intel_cpufreq_fast_switch,
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.init = intel_cpufreq_cpu_init,
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.exit = intel_pstate_cpu_exit,
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.stop_cpu = intel_cpufreq_stop_cpu,
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.name = "intel_cpufreq",
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};
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static struct cpufreq_driver *intel_pstate_driver = &intel_pstate;
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static int no_load __initdata;
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static int no_hwp __initdata;
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static int hwp_only __initdata;
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@ -1976,7 +2115,7 @@ hwp_cpu_matched:
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intel_pstate_request_control_from_smm();
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rc = cpufreq_register_driver(&intel_pstate_driver);
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rc = cpufreq_register_driver(intel_pstate_driver);
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if (rc)
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goto out;
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@ -1991,7 +2130,9 @@ out:
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get_online_cpus();
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for_each_online_cpu(cpu) {
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if (all_cpu_data[cpu]) {
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intel_pstate_clear_update_util_hook(cpu);
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if (intel_pstate_driver == &intel_pstate)
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intel_pstate_clear_update_util_hook(cpu);
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kfree(all_cpu_data[cpu]);
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}
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}
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@ -2007,8 +2148,13 @@ static int __init intel_pstate_setup(char *str)
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if (!str)
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return -EINVAL;
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if (!strcmp(str, "disable"))
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if (!strcmp(str, "disable")) {
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no_load = 1;
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} else if (!strcmp(str, "passive")) {
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pr_info("Passive mode enabled\n");
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intel_pstate_driver = &intel_cpufreq;
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no_hwp = 1;
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}
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if (!strcmp(str, "no_hwp")) {
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pr_info("HWP disabled\n");
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no_hwp = 1;
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