struct uclamp_rq was zeroed out entirely in assumption that in the first
call to uclamp_rq_inc() they'd be initialized correctly in accordance to
default settings.
But when next patch introduces a static key to skip
uclamp_rq_{inc,dec}() until userspace opts in to use uclamp, schedutil
will fail to perform any frequency changes because the
rq->uclamp[UCLAMP_MAX].value is zeroed at init and stays as such. Which
means all rqs are capped to 0 by default.
Fix it by making sure we do proper initialization at init without
relying on uclamp_rq_inc() doing it later.
Fixes: 69842cba9ace ("sched/uclamp: Add CPU's clamp buckets refcounting")
Signed-off-by: Qais Yousef <qais.you...@arm.com>
Cc: Juri Lelli <juri.le...@redhat.com>
Cc: Vincent Guittot <vincent.guit...@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggem...@arm.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Ben Segall <bseg...@google.com>
Cc: Mel Gorman <mgor...@suse.de>
CC: Patrick Bellasi <patrick.bell...@matbug.net>
Cc: Chris Redpath <chris.redp...@arm.com>
Cc: Lukasz Luba <lukasz.l...@arm.com>
Cc: linux-kernel@vger.kernel.org
---
kernel/sched/core.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a43c84c27c6f..4265861e13e9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1248,6 +1248,22 @@ static void uclamp_fork(struct task_struct *p)
}
}
+static void __init init_uclamp_rq(struct rq *rq)
+{
+ enum uclamp_id clamp_id;
+ struct uclamp_rq *uc_rq = rq->uclamp;
+
+ for_each_clamp_id(clamp_id) {
+ memset(uc_rq[clamp_id].bucket,
+ 0,
+ sizeof(struct uclamp_bucket)*UCLAMP_BUCKETS);
+
+ uc_rq[clamp_id].value = uclamp_none(clamp_id);
+ }
+
+ rq->uclamp_flags = 0;
+}
+
static void __init init_uclamp(void)
{
struct uclamp_se uc_max = {};
@@ -1256,11 +1272,8 @@ static void __init init_uclamp(void)
mutex_init(&uclamp_mutex);
- for_each_possible_cpu(cpu) {
- memset(&cpu_rq(cpu)->uclamp, 0,
- sizeof(struct uclamp_rq)*UCLAMP_CNT);
- cpu_rq(cpu)->uclamp_flags = 0;
- }
+ for_each_possible_cpu(cpu)
+ init_uclamp_rq(cpu_rq(cpu));
for_each_clamp_id(clamp_id) {
uclamp_se_set(&init_task.uclamp_req[clamp_id],
--
2.17.1
