linux-kernel - [PATCH 3/3] sched/fair: remove impossible condition from find_idlest_group

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Message-Id: <20171215153944.220146-3-joelaf@google.com>
Date:   Fri, 15 Dec 2017 07:39:44 -0800
From:   Joel Fernandes <joelaf@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     Joel Fernandes <joelaf@...gle.com>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        Len Brown <lenb@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@....com>,
        Patrick Bellasi <patrick.bellasi@....com>,
        Chris Redpath <Chris.Redpath@....com>,
        Steve Muckle <smuckle@...gle.com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Ramussen <morten.rasmussen@....com>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Saravana Kannan <skannan@...cinc.com>,
        Vikram Mulukutla <markivx@...eaurora.org>,
        Rohit Jain <rohit.k.jain@...cle.com>,
        Atish Patra <atish.patra@...cle.com>,
        Josef Bacik <jbacik@...com>,
        EAS Dev <eas-dev@...ts.linaro.org>,
        Android Kernel <kernel-team@...roid.com>
Subject: [PATCH 3/3] sched/fair: remove impossible condition from find_idlest_group_cpu

find_idlest_group_cpu goes through CPUs of a group previous selected by
find_idlest_group. find_idlest_group returns NULL if the local group is the
selected one and doesn't execute find_idlest_group_cpu if the group to which
'cpu' belongs to is chosen. So we're always guaranteed to call
find_idlest_group_cpu with a group to which cpu is non-local. This makes one of
the conditions in find_idlest_group_cpu an impossible one, which we can get rid
off.

Reviewed-by: Brendan Jackman <brendan.jackman@....com>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
Signed-off-by: Joel Fernandes <joelaf@...gle.com>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1b10821d8380..44407e703b5f 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5948,7 +5948,7 @@ find_idlest_group_cpu(struct sched_group *group, struct task_struct *p, int this
 			}
 		} else if (shallowest_idle_cpu == -1) {
 			load = weighted_cpuload(cpu_rq(i));
-			if (load < min_load || (load == min_load && i == this_cpu)) {
+			if (load < min_load) {
 				min_load = load;
 				least_loaded_cpu = i;
 			}
-- 
2.15.1.504.g5279b80103-goog