evie/android_kernel_oneplus_msm8998
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sched: avoid RT tasks contention during sched boost

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When placement boost is active, we are currently considering
only the highest capacity cluster. If all of the active CPUs
in this cluster are busy with RT tasks, the waking task is
placed on it's previous CPU, which may be running a RT task.
This results in suboptimal performance. Fix this by expanding
the search to the other clusters, when there is no eligible CPU
found in the highest capacity cluster.

Change-Id: Iaab2e397b994c2b219dc086c7a6fa91ca26a5128
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>
This commit is contained in:
Pavankumar Kondeti 2017-07-14 19:26:34 +05:30
parent d9fbe4b921
commit f261bf42cc
1 changed files with 15 additions and 0 deletions
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15
kernel/sched/rt.c
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@ -1823,6 +1823,7 @@ static int find_lowest_rq_hmp(struct task_struct *task)
* the best one based on our affinity and topology.
*/
retry:
for_each_sched_cluster(cluster) {
if (boost_on_big && cluster->capacity != max_possible_capacity)
continue;
@ -1830,6 +1831,15 @@ static int find_lowest_rq_hmp(struct task_struct *task)
cpumask_and(&candidate_mask, &cluster->cpus, lowest_mask);
cpumask_andnot(&candidate_mask, &candidate_mask,
cpu_isolated_mask);
/*
* When placement boost is active, if there is no eligible CPU
* in the highest capacity cluster, we fallback to the other
* clusters. So clear the CPUs of the traversed cluster from
* the lowest_mask.
*/
if (unlikely(boost_on_big))
cpumask_andnot(lowest_mask, lowest_mask,
&cluster->cpus);
if (cpumask_empty(&candidate_mask))
continue;
@ -1869,6 +1879,11 @@ static int find_lowest_rq_hmp(struct task_struct *task)
break;
}
if (unlikely(boost_on_big && best_cpu == -1)) {
boost_on_big = 0;
goto retry;
}
return best_cpu;
}
#endif /* CONFIG_SCHED_HMP */