From: Qais Yousef <qais.yousef@arm.com>
To: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>,
Qais Yousef <qais.yousef@arm.com>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Patrick Bellasi <patrick.bellasi@matbug.net>,
Chris Redpath <chris.redpath@arm.com>,
Lukasz Luba <lukasz.luba@arm.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v4 1/2] sched/uclamp: Fix initialization of struct uclamp_rq
Date: Thu, 25 Jun 2020 16:43:51 +0100 [thread overview]
Message-ID: <20200625154352.24767-2-qais.yousef@arm.com> (raw)
In-Reply-To: <20200625154352.24767-1-qais.yousef@arm.com>
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")
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Mel Gorman <mgorman@suse.de>
CC: Patrick Bellasi <patrick.bellasi@matbug.net>
Cc: Chris Redpath <chris.redpath@arm.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: linux-kernel@vger.kernel.org
---
kernel/sched/core.c | 21 ++++++++++++++++-----
1 file changed, 16 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8fe2ac910bed..235b2cae00a0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1248,6 +1248,20 @@ 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) {
+ uc_rq[clamp_id] = (struct uclamp_rq) {
+ .value = uclamp_none(clamp_id)
+ };
+ }
+
+ rq->uclamp_flags = 0;
+}
+
static void __init init_uclamp(void)
{
struct uclamp_se uc_max = {};
@@ -1256,11 +1270,8 @@ 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
next prev parent reply other threads:[~2020-06-25 15:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 15:43 [PATCH v4 0/2] sched: Optionally skip uclamp logic in fast path Qais Yousef
2020-06-25 15:43 ` Qais Yousef [this message]
2020-06-26 12:32 ` [PATCH v4 1/2] sched/uclamp: Fix initialization of struct uclamp_rq Patrick Bellasi
2020-06-26 23:17 ` Valentin Schneider
2020-06-29 12:12 ` Qais Yousef
2020-06-25 15:43 ` [PATCH v4 2/2] sched/uclamp: Protect uclamp fast path code with static key Qais Yousef
2020-06-26 12:38 ` Patrick Bellasi
2020-06-26 23:21 ` Valentin Schneider
2020-06-29 12:21 ` Qais Yousef
2020-06-26 10:00 ` [PATCH v4 0/2] sched: Optionally skip uclamp logic in fast path Lukasz Luba
2020-06-26 10:27 ` Peter Zijlstra
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