On 11 September 2014 14:34, Peter Zijlstra peterz@infradead.org wrote:
On Tue, Aug 26, 2014 at 01:06:53PM +0200, Vincent Guittot wrote:
Monitor the utilization level of each group of each sched_domain level. The utilization is the amount of cpu_capacity that is currently used on a CPU or group of CPUs. We use the usage_load_avg to evaluate this utilization level. In the special use case where the CPU is fully loaded by more than 1 task, the activity level is set above the cpu_capacity in order to reflect the overload of the CPU
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org
kernel/sched/fair.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1fd2131..2f95d1c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4126,6 +4126,11 @@ static unsigned long capacity_of(int cpu) return cpu_rq(cpu)->cpu_capacity; }
+static unsigned long capacity_orig_of(int cpu) +{
return cpu_rq(cpu)->cpu_capacity_orig;+}
static unsigned long cpu_avg_load_per_task(int cpu) { struct rq *rq = cpu_rq(cpu);
This hunk should probably go into patch 6.
@@ -4514,6 +4519,17 @@ static int select_idle_sibling(struct task_struct *p, int target) return target; }
+static int get_cpu_utilization(int cpu) +{
unsigned long usage = cpu_rq(cpu)->cfs.usage_load_avg;unsigned long capacity = capacity_of(cpu);if (usage >= SCHED_LOAD_SCALE)return capacity + 1;return (usage * capacity) >> SCHED_LOAD_SHIFT;+}
So if I understood patch 9 correct, your changelog is iffy. usage_load_avg should never get > 1 (of whatever unit), no matter how many tasks are on the rq. You can only maximally run all the time.
Therefore I can only interpret the if (usage >= SCHED_LOAD_SCALE) as numerical error handling, nothing more.
yes
Also I'm not entirely sure I like the usage, utilization names/metrics. I would suggest to reverse them. Call the pure running number 'utilization' and this scaled with capacity 'usage' or so.
ok. i can invert 'usage' and 'utilization', which will give
s/get_cpu_utilization/get_cpu_usage/ s/sgs->group_utilization/sgs->group_usage/ s/cfs.usage_load_avg/cfs.utilization_load_avg/ s/se->avg.usage_avg_contrib/se->avg.utilization_avg_contrib s/__update_task_entity_usage/__update_task_entity_utilization s/__update_entity_usage_avg_contrib/__update_entity_utilization_avg_contrib
@@ -6188,7 +6206,6 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd /* Now, start updating sd_lb_stats */ sds->total_load += sgs->group_load; sds->total_capacity += sgs->group_capacity;
sg = sg->next; } while (sg != env->sd->groups);I like that extra line of whitespace, it separates the body from the loop itself.
Sorry, i don't know why i remove it