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author | 2021-01-19 09:35:42 +0100 | |
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committer | 2021-02-17 14:12:42 +0100 | |
commit | de40f33e788b0c016bfde512ace2f76339ef7ddb (patch) | |
tree | 3fd7809b0ebcad750b2351a58e95c227660fcdc9 /kernel/sched/deadline.c | |
parent | uprobes: (Re)add missing get_uprobe() in __find_uprobe() (diff) | |
download | linux-de40f33e788b0c016bfde512ace2f76339ef7ddb.tar.gz linux-de40f33e788b0c016bfde512ace2f76339ef7ddb.tar.bz2 linux-de40f33e788b0c016bfde512ace2f76339ef7ddb.zip |
sched/deadline: Reduce rq lock contention in dl_add_task_root_domain()
dl_add_task_root_domain() is called during sched domain rebuild:
rebuild_sched_domains_locked()
partition_and_rebuild_sched_domains()
rebuild_root_domains()
for all top_cpuset descendants:
update_tasks_root_domain()
for all tasks of cpuset:
dl_add_task_root_domain()
Change it so that only the task pi lock is taken to check if the task
has a SCHED_DEADLINE (DL) policy. In case that p is a DL task take the
rq lock as well to be able to safely de-reference root domain's DL
bandwidth structure.
Most of the tasks will have another policy (namely SCHED_NORMAL) and
can now bail without taking the rq lock.
One thing to note here: Even in case that there aren't any DL user
tasks, a slow frequency switching system with cpufreq gov schedutil has
a DL task (sugov) per frequency domain running which participates in DL
bandwidth management.
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Quentin Perret <qperret@google.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20210119083542.19856-1-dietmar.eggemann@arm.com
Diffstat (limited to 'kernel/sched/deadline.c')
-rw-r--r-- | kernel/sched/deadline.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 1508d126e88b..6f377969fa71 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2388,9 +2388,13 @@ void dl_add_task_root_domain(struct task_struct *p) struct rq *rq; struct dl_bw *dl_b; - rq = task_rq_lock(p, &rf); - if (!dl_task(p)) - goto unlock; + raw_spin_lock_irqsave(&p->pi_lock, rf.flags); + if (!dl_task(p)) { + raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags); + return; + } + + rq = __task_rq_lock(p, &rf); dl_b = &rq->rd->dl_bw; raw_spin_lock(&dl_b->lock); @@ -2399,7 +2403,6 @@ void dl_add_task_root_domain(struct task_struct *p) raw_spin_unlock(&dl_b->lock); -unlock: task_rq_unlock(rq, p, &rf); } |