lkml.org 
[lkml]   [2020]   [Jun]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/2] sched/uclamp: Fix initialization of strut uclamp_rq
Date
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
\
 
 \ /
  Last update: 2020-06-18 21:56    [W:0.117 / U:0.776 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site