From: Qais Yousef <qais.yousef@arm.com>
To: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Cc: 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 <chrid.redpath@arm.com>,
Lukasz Luba <lukasz.luba@arm.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] sched/uclamp: Fix initialization of strut uclamp_rq
Date: Thu, 18 Jun 2020 20:55:24 +0100 [thread overview]
Message-ID: <20200618195525.7889-2-qais.yousef@arm.com> (raw)
In-Reply-To: <20200618195525.7889-1-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")
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 <chrid.redpath@arm.com>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: linux-kernel@vger.kernel.org
---
kernel/sched/core.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a43c84c27c6f..e19d2b915406 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) {
+ memset(uc_rq[clamp_id].bucket,
+ 0,
+ sizeof(struct uclamp_bucket)*UCLAMP_BUCKETS);
+
+ uc_rq[clamp_id].value = uclamp_none(clamp_id);
+ }
+}
+
static void __init init_uclamp(void)
{
struct uclamp_se uc_max = {};
@@ -1257,8 +1271,7 @@ 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);
+ init_uclamp_rq(cpu_rq(cpu));
cpu_rq(cpu)->uclamp_flags = 0;
}
--
2.17.1
next prev parent reply other threads:[~2020-06-18 19:55 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-18 19:55 [PATCH 0/2] sched: Optionally skip uclamp logic in fast path Qais Yousef
2020-06-18 19:55 ` Qais Yousef [this message]
2020-06-19 10:36 ` [PATCH 1/2] sched/uclamp: Fix initialization of strut uclamp_rq Valentin Schneider
2020-06-19 17:30 ` Peter Zijlstra
2020-06-19 17:39 ` Qais Yousef
2020-06-19 18:13 ` Peter Zijlstra
2020-06-19 18:42 ` Qais Yousef
2020-06-22 10:30 ` Qais Yousef
2020-06-18 19:55 ` [PATCH 2/2] sched/uclamp: Protect uclamp fast path code with static key Qais Yousef
2020-06-19 10:36 ` Valentin Schneider
2020-06-19 11:57 ` Mel Gorman
2020-06-19 12:17 ` Valentin Schneider
2020-06-19 12:55 ` Qais Yousef
2020-06-19 14:51 ` Qais Yousef
2020-06-19 12:51 ` Qais Yousef
2020-06-19 13:23 ` Steven Rostedt
2020-06-19 13:25 ` Valentin Schneider
2020-06-19 14:13 ` Qais Yousef
2020-06-19 15:17 ` Valentin Schneider
2020-06-19 17:25 ` Qais Yousef
2020-06-19 18:52 ` Valentin Schneider
2020-06-19 19:47 ` Peter Zijlstra
2020-06-19 10:39 ` Valentin Schneider
2020-06-19 17:45 ` Peter Zijlstra
2020-06-19 17:53 ` Qais Yousef
2020-06-22 9:06 ` [PATCH 0/2] sched: Optionally skip uclamp logic in fast path Lukasz Luba
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