diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 3 | ||||
| -rw-r--r-- | Documentation/admin-guide/pm/intel_pstate.rst | 3 | ||||
| -rw-r--r-- | drivers/cpufreq/cpufreq_governor.c | 45 | ||||
| -rw-r--r-- | drivers/cpufreq/intel_pstate.c | 27 |
4 files changed, 47 insertions, 31 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb8752b42ec8..77e671e55993 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2316,6 +2316,9 @@ per_cpu_perf_limits Allow per-logical-CPU P-State performance control limits using cpufreq sysfs interface + no_cas + Do not enable capacity-aware scheduling (CAS) on + hybrid systems intremap= [X86-64,Intel-IOMMU,EARLY] on enable Interrupt Remapping (default) diff --git a/Documentation/admin-guide/pm/intel_pstate.rst b/Documentation/admin-guide/pm/intel_pstate.rst index bf13ad25a32f..78fc83ed2a7e 100644 --- a/Documentation/admin-guide/pm/intel_pstate.rst +++ b/Documentation/admin-guide/pm/intel_pstate.rst @@ -696,6 +696,9 @@ of them have to be prepended with the ``intel_pstate=`` prefix. Use per-logical-CPU P-State limits (see `Coordination of P-state Limits`_ for details). +``no_cas`` + Do not enable capacity-aware scheduling (CAS) which is enabled by + default on hybrid systems. Diagnostics and Tuning ====================== diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index af44ee6a6430..1a7fcaf39cc9 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -145,7 +145,23 @@ unsigned int dbs_update(struct cpufreq_policy *policy) time_elapsed = update_time - j_cdbs->prev_update_time; j_cdbs->prev_update_time = update_time; - idle_time = cur_idle_time - j_cdbs->prev_cpu_idle; + /* + * cur_idle_time could be smaller than j_cdbs->prev_cpu_idle if + * it's obtained from get_cpu_idle_time_jiffy() when NOHZ is + * off, where idle_time is calculated by the difference between + * time elapsed in jiffies and "busy time" obtained from CPU + * statistics. If a CPU is 100% busy, the time elapsed and busy + * time should grow with the same amount in two consecutive + * samples, but in practice there could be a tiny difference, + * making the accumulated idle time decrease sometimes. Hence, + * in this case, idle_time should be regarded as 0 in order to + * make the further process correct. + */ + if (cur_idle_time > j_cdbs->prev_cpu_idle) + idle_time = cur_idle_time - j_cdbs->prev_cpu_idle; + else + idle_time = 0; + j_cdbs->prev_cpu_idle = cur_idle_time; if (ignore_nice) { @@ -162,7 +178,7 @@ unsigned int dbs_update(struct cpufreq_policy *policy) * calls, so the previous load value can be used then. */ load = j_cdbs->prev_load; - } else if (unlikely((int)idle_time > 2 * sampling_rate && + } else if (unlikely(idle_time > 2 * sampling_rate && j_cdbs->prev_load)) { /* * If the CPU had gone completely idle and a task has @@ -189,30 +205,15 @@ unsigned int dbs_update(struct cpufreq_policy *policy) load = j_cdbs->prev_load; j_cdbs->prev_load = 0; } else { - if (time_elapsed >= idle_time) { + if (time_elapsed > idle_time) load = 100 * (time_elapsed - idle_time) / time_elapsed; - } else { - /* - * That can happen if idle_time is returned by - * get_cpu_idle_time_jiffy(). In that case - * idle_time is roughly equal to the difference - * between time_elapsed and "busy time" obtained - * from CPU statistics. Then, the "busy time" - * can end up being greater than time_elapsed - * (for example, if jiffies_64 and the CPU - * statistics are updated by different CPUs), - * so idle_time may in fact be negative. That - * means, though, that the CPU was busy all - * the time (on the rough average) during the - * last sampling interval and 100 can be - * returned as the load. - */ - load = (int)idle_time < 0 ? 100 : 0; - } + else + load = 0; + j_cdbs->prev_load = load; } - if (unlikely((int)idle_time > 2 * sampling_rate)) { + if (unlikely(idle_time > 2 * sampling_rate)) { unsigned int periods = idle_time / sampling_rate; if (periods < idle_periods) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 9c4cc01fd51a..fa81054fa411 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -936,6 +936,8 @@ static struct freq_attr *hwp_cpufreq_attrs[] = { NULL, }; +static bool no_cas __ro_after_init; + static struct cpudata *hybrid_max_perf_cpu __read_mostly; /* * Protects hybrid_max_perf_cpu, the capacity_perf fields in struct cpudata, @@ -1041,6 +1043,10 @@ static void hybrid_refresh_cpu_capacity_scaling(void) static void hybrid_init_cpu_capacity_scaling(bool refresh) { + /* Bail out if enabling capacity-aware scheduling is prohibited. */ + if (no_cas) + return; + /* * If hybrid_max_perf_cpu is set at this point, the hybrid CPU capacity * scaling has been enabled already and the driver is just changing the @@ -3688,6 +3694,15 @@ static int __init intel_pstate_init(void) if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) return -ENODEV; + /* + * The Intel pstate driver will be ignored if the platform + * firmware has its own power management modes. + */ + if (intel_pstate_platform_pwr_mgmt_exists()) { + pr_info("P-states controlled by the platform\n"); + return -ENODEV; + } + id = x86_match_cpu(hwp_support_ids); if (id) { hwp_forced = intel_pstate_hwp_is_enabled(); @@ -3743,15 +3758,6 @@ static int __init intel_pstate_init(void) default_driver = &intel_cpufreq; hwp_cpu_matched: - /* - * The Intel pstate driver will be ignored if the platform - * firmware has its own power management modes. - */ - if (intel_pstate_platform_pwr_mgmt_exists()) { - pr_info("P-states controlled by the platform\n"); - return -ENODEV; - } - if (!hwp_active && hwp_only) return -ENOTSUPP; @@ -3835,6 +3841,9 @@ static int __init intel_pstate_setup(char *str) if (!strcmp(str, "no_hwp")) no_hwp = 1; + if (!strcmp(str, "no_cas")) + no_cas = true; + if (!strcmp(str, "force")) force_load = 1; if (!strcmp(str, "hwp_only")) |