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sched/fair: Fix !CONFIG_SMP kernel cpufreq governor breakage 

The following commit:

  34e2c555f3 ("cpufreq: Add mechanism for registering utilization update callbacks")

overlooked the fact that update_load_avg(), where CFS invokes cpufreq
utilization update callbacks, becomes an empty stub on UP kernels.

In consequence, if !CONFIG_SMP, cpufreq governors are never invoked
from CFS and they do not have a chance to evaluate CPU performace
levels and update them often enough.

Needless to say, things don't work as expected then.

Fix the problem by making the !CONFIG_SMP stub of update_load_avg()
invoke cpufreq update callbacks too.

Reported-by: Steve Muckle <steve.muckle@linaro.org>
Tested-by: Steve Muckle <steve.muckle@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Steve Muckle <steve.muckle@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux PM list <linux-pm@vger.kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Fixes: 34e2c555f3 (cpufreq: Add mechanism for registering utilization update callbacks)
Link: http://lkml.kernel.org/r/6282396.VVEdgVYxO3@vostro.rjw.lan
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Rafael J. Wysocki 2016-05-06 14:58:43 +02:00 committed by Ingo Molnar
parent 2548d546d4
commit 536bd00cdb
1 changed files with 8 additions and 1 deletions
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9
kernel/sched/fair.c
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@ -3030,7 +3030,14 @@ static int idle_balance(struct rq *this_rq);
#else /* CONFIG_SMP */
static inline void update_load_avg(struct sched_entity *se, int update_tg) {}
static inline void update_load_avg(struct sched_entity *se, int not_used)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
struct rq *rq = rq_of(cfs_rq);
cpufreq_trigger_update(rq_clock(rq));
}
static inline void
enqueue_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se) {}
static inline void