From a240c4aa5d0f9c8bb0db380ab9c1ec1f68b923ad Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 2 Mar 2017 23:29:12 +0100 Subject: [PATCH] cpufreq: intel_pstate: Do not reinit performance limits in ->setpolicy If the current P-state selection algorithm is set to "performance" in intel_pstate_set_policy(), the limits may be initialized from scratch, but only if no_turbo is not set and the maximum frequency allowed for the given CPU (i.e. the policy object representing it) is at least equal to the max frequency supported by the CPU. In all of the other cases, the limits will not be updated. For example, the following can happen: # cat intel_pstate/status active # echo performance > cpufreq/policy0/scaling_governor # cat intel_pstate/min_perf_pct 100 # echo 94 > intel_pstate/min_perf_pct # cat intel_pstate/min_perf_pct 100 # cat cpufreq/policy0/scaling_max_freq 3100000 echo 3000000 > cpufreq/policy0/scaling_max_freq # cat intel_pstate/min_perf_pct 94 # echo 95 > intel_pstate/min_perf_pct # cat intel_pstate/min_perf_pct 95 That is confusing for two reasons. First, the initial attempt to change min_perf_pct to 94 seems to have no effect, even though setting the global limits should always work. Second, after changing scaling_max_freq for policy0 the global min_perf_pct attribute shows 94, even though it should have not been affected by that operation in principle. Moreover, the final attempt to change min_perf_pct to 95 worked as expected, because scaling_max_freq for the only policy with scaling_governor equal to "performance" was different from the maximum at that time. To make all that confusion go away, modify intel_pstate_set_policy() so that it doesn't reinitialize the limits at all. At the same time, change intel_pstate_set_performance_limits() to set min_sysfs_pct to 100 in the "performance" limits set so that switching the P-state selection algorithm to "performance" causes intel_pstate/min_perf_pct in sysfs to go to 100 (or whatever value min_sysfs_pct in the "performance" limits is set to later). That requires per-CPU limits to be initialized explicitly rather than by copying the global limits to avoid setting min_sysfs_pct in the per-CPU limits to 100. Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/intel_pstate.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index 3dc546601c88..f1f8fbe0b4c4 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -382,6 +382,7 @@ static void intel_pstate_set_performance_limits(struct perf_limits *limits) intel_pstate_init_limits(limits); limits->min_perf_pct = 100; limits->min_perf = int_ext_tofp(1); + limits->min_sysfs_pct = 100; } static DEFINE_MUTEX(intel_pstate_driver_lock); @@ -2146,16 +2147,11 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) mutex_lock(&intel_pstate_limits_lock); if (policy->policy == CPUFREQ_POLICY_PERFORMANCE) { + pr_debug("set performance\n"); if (!perf_limits) { limits = &performance_limits; perf_limits = limits; } - if (policy->max >= policy->cpuinfo.max_freq && - !limits->no_turbo) { - pr_debug("set performance\n"); - intel_pstate_set_performance_limits(perf_limits); - goto out; - } } else { pr_debug("set powersave\n"); if (!perf_limits) { @@ -2166,7 +2162,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) } intel_pstate_update_perf_limits(policy, perf_limits); - out: + if (cpu->policy == CPUFREQ_POLICY_PERFORMANCE) { /* * NOHZ_FULL CPUs need this as the governor callback may not @@ -2257,13 +2253,8 @@ static int __intel_pstate_cpu_init(struct cpufreq_policy *policy) cpu = all_cpu_data[policy->cpu]; - /* - * We need sane value in the cpu->perf_limits, so inherit from global - * perf_limits limits, which are seeded with values based on the - * CONFIG_CPU_FREQ_DEFAULT_GOV_*, during boot up. - */ if (per_cpu_limits) - memcpy(cpu->perf_limits, limits, sizeof(struct perf_limits)); + intel_pstate_init_limits(cpu->perf_limits); policy->min = cpu->pstate.min_pstate * cpu->pstate.scaling; policy->max = cpu->pstate.turbo_pstate * cpu->pstate.scaling; -- 2.20.1