On Fri, Sep 26, 2014 at 01:17:43PM +0100, Vincent Guittot wrote:
On 25 September 2014 21:05, Dietmar Eggemann dietmar.eggemann@arm.com wrote:
On 23/09/14 17:08, Vincent Guittot wrote:
Monitor the usage level of each group of each sched_domain level. The usage is the amount of cpu_capacity that is currently used on a CPU or group of CPUs. We use the utilization_load_avg to evaluate the usage level of each group.
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org
kernel/sched/fair.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 2cf153d..4097e3f 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4523,6 +4523,17 @@ static int select_idle_sibling(struct task_struct *p, int target) return target; }
+static int get_cpu_usage(int cpu) +{
unsigned long usage = cpu_rq(cpu)->cfs.utilization_load_avg;unsigned long capacity = capacity_orig_of(cpu);if (usage >= SCHED_LOAD_SCALE)return capacity + 1;Why you are returning rq->cpu_capacity_orig + 1 (1025) in case utilization_load_avg is greater or equal than 1024 and not usage or (usage * capacity) >> SCHED_LOAD_SHIFT too?
The usage can't be higher than the full capacity of the CPU because it's about the running time on this CPU. Nevertheless, usage can be higher than SCHED_LOAD_SCALE because of unfortunate rounding in avg_period and running_load_avg or just after migrating tasks until the average stabilizes with the new running time.
I fully agree that the cpu usage should be capped to capacity, but why do you return capacity + 1? I would just return capacity, no?
Now that you have gotten rid of 'usage' everywhere else, shouldn't this function be renamed to get_cpu_utilization()?