Users can perform clustered scheduling using the cpuset facility. After an exclusive cpuset is created, task migrations happen only between CPUs belonging to the same cpuset. Inter- cpuset migrations can only happen when the user requires so, moving a task between different cpusets. This behaviour is broken in SCHED_DEADLINE, as currently spurious inter- cpuset migration may happen without user intervention.
This patch fix the problem (and shuffles the code a bit to improve clarity). Signed-off-by: Juri Lelli <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Juri Lelli <[email protected]> Cc: Dario Faggioli <[email protected]> Cc: Michael Trimarchi <[email protected]> Cc: Fabio Checconi <[email protected]> Cc: [email protected] --- kernel/sched/cpudeadline.c | 4 +--- kernel/sched/deadline.c | 7 +++++++ 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index bd95963..539ca3c 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -107,9 +107,7 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, int best_cpu = -1; const struct sched_dl_entity *dl_se = &p->dl; - if (later_mask && cpumask_and(later_mask, cp->free_cpus, - &p->cpus_allowed) && cpumask_and(later_mask, - later_mask, cpu_active_mask)) { + if (later_mask && cpumask_and(later_mask, later_mask, cp->free_cpus)) { best_cpu = cpumask_any(later_mask); goto out; } else if (cpumask_test_cpu(cpudl_maximum(cp), &p->cpus_allowed) && diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 56cb157..2799441 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1169,6 +1169,13 @@ static int find_later_rq(struct task_struct *task) if (task->nr_cpus_allowed == 1) return -1; + /* + * We have to consider system topology and task affinity + * first, then we can look for a suitable cpu. + */ + cpumask_copy(later_mask, task_rq(task)->rd->span); + cpumask_and(later_mask, later_mask, cpu_active_mask); + cpumask_and(later_mask, later_mask, &task->cpus_allowed); best_cpu = cpudl_find(&task_rq(task)->rd->cpudl, task, later_mask); if (best_cpu == -1) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
