diff options
author | Viresh Kumar <viresh.kumar@linaro.org> | 2016-02-22 10:27:46 +0530 |
---|---|---|
committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-02-23 01:10:44 +0100 |
commit | 41cfd64cf49fc84837341732a142f3d4cdc1e83a (patch) | |
tree | 17c5df52e17cd1e7272562c455caab327dce1df5 /drivers | |
parent | fd7dc7e6b6521453d1170dc1ed50320024b5ba9d (diff) |
intel_pstate: Update frequencies of policy->cpus only from ->set_policy()
The intel-pstate driver is using intel_pstate_hwp_set() from two
separate paths, i.e. ->set_policy() callback and sysfs update path for
the files present in /sys/devices/system/cpu/intel_pstate/ directory.
While an update to the sysfs path applies to all the CPUs being managed
by the driver (which essentially means all the online CPUs), the update
via the ->set_policy() callback applies to a smaller group of CPUs
managed by the policy for which ->set_policy() is called.
And so, intel_pstate_hwp_set() should update frequencies of only the
CPUs that are part of policy->cpus mask, while it is called from
->set_policy() callback.
In order to do that, add a parameter (cpumask) to intel_pstate_hwp_set()
and apply the frequency changes only to the concerned CPUs.
For ->set_policy() path, we are only concerned about policy->cpus, and
so policy->rwsem lock taken by the core prior to calling ->set_policy()
is enough to take care of any races. The larger lock acquired by
get_online_cpus() is required only for the updates to sysfs files.
Add another routine, intel_pstate_hwp_set_online_cpus(), and call it
from the sysfs update paths.
This also fixes a lockdep reported recently, where policy->rwsem and
get_online_cpus() could have been acquired in any order causing an ABBA
deadlock. The sequence of events leading to that was:
intel_pstate_init(...)
...cpufreq_online(...)
down_write(&policy->rwsem); // Locks policy->rwsem
...
cpufreq_init_policy(policy);
...intel_pstate_hwp_set();
get_online_cpus(); // Temporarily locks cpu_hotplug.lock
...
up_write(&policy->rwsem);
pm_suspend(...)
...disable_nonboot_cpus()
_cpu_down()
cpu_hotplug_begin(); // Locks cpu_hotplug.lock
__cpu_notify(CPU_DOWN_PREPARE, ...);
...cpufreq_offline_prepare();
down_write(&policy->rwsem); // Locks policy->rwsem
Reported-and-tested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/cpufreq/intel_pstate.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index cd83d477e32d..e85677653ef8 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -286,7 +286,7 @@ static inline void update_turbo_state(void) cpu->pstate.max_pstate == cpu->pstate.turbo_pstate); } -static void intel_pstate_hwp_set(void) +static void intel_pstate_hwp_set(const struct cpumask *cpumask) { int min, hw_min, max, hw_max, cpu, range, adj_range; u64 value, cap; @@ -296,9 +296,7 @@ static void intel_pstate_hwp_set(void) hw_max = HWP_HIGHEST_PERF(cap); range = hw_max - hw_min; - get_online_cpus(); - - for_each_online_cpu(cpu) { + for_each_cpu(cpu, cpumask) { rdmsrl_on_cpu(cpu, MSR_HWP_REQUEST, &value); adj_range = limits->min_perf_pct * range / 100; min = hw_min + adj_range; @@ -317,7 +315,12 @@ static void intel_pstate_hwp_set(void) value |= HWP_MAX_PERF(max); wrmsrl_on_cpu(cpu, MSR_HWP_REQUEST, value); } +} +static void intel_pstate_hwp_set_online_cpus(void) +{ + get_online_cpus(); + intel_pstate_hwp_set(cpu_online_mask); put_online_cpus(); } @@ -439,7 +442,7 @@ static ssize_t store_no_turbo(struct kobject *a, struct attribute *b, limits->no_turbo = clamp_t(int, input, 0, 1); if (hwp_active) - intel_pstate_hwp_set(); + intel_pstate_hwp_set_online_cpus(); return count; } @@ -465,7 +468,7 @@ static ssize_t store_max_perf_pct(struct kobject *a, struct attribute *b, int_tofp(100)); if (hwp_active) - intel_pstate_hwp_set(); + intel_pstate_hwp_set_online_cpus(); return count; } @@ -490,7 +493,7 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b, int_tofp(100)); if (hwp_active) - intel_pstate_hwp_set(); + intel_pstate_hwp_set_online_cpus(); return count; } @@ -1141,7 +1144,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) pr_debug("intel_pstate: set performance\n"); limits = &performance_limits; if (hwp_active) - intel_pstate_hwp_set(); + intel_pstate_hwp_set(policy->cpus); return 0; } @@ -1173,7 +1176,7 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy) int_tofp(100)); if (hwp_active) - intel_pstate_hwp_set(); + intel_pstate_hwp_set(policy->cpus); return 0; } |