linux-kernel - [PATCH] cpufreq: schedutil: Combine two loops into one in sugov

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230324100023.900616-1-yajun.deng@linux.dev>
Date:   Fri, 24 Mar 2023 18:00:23 +0800
From:   Yajun Deng <yajun.deng@...ux.dev>
To:     rafael@...nel.org, viresh.kumar@...aro.org, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yajun Deng <yajun.deng@...ux.dev>
Subject: [PATCH] cpufreq: schedutil: Combine two loops into one in sugov_start()

The sugov_start() function currently contains two for loops that
traverse the CPU list and perform some initialization tasks. The first
loop initializes each sugov_cpu struct and assigns the CPU number and
sugov_policy pointer. The second loop sets up the update_util hook for
each CPU based on the policy type.

Since both loops operate on the same CPU list, it is possible to combine
them into a single for loop. This simplifies the code and reduces the
number of times the CPU list needs to be traversed, which can improve
performance.

Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
---
 kernel/sched/cpufreq_schedutil.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index e3211455b203..9a28ebbb9c1e 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -766,14 +766,6 @@ static int sugov_start(struct cpufreq_policy *policy)
 
 	sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
 
-	for_each_cpu(cpu, policy->cpus) {
-		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
-
-		memset(sg_cpu, 0, sizeof(*sg_cpu));
-		sg_cpu->cpu			= cpu;
-		sg_cpu->sg_policy		= sg_policy;
-	}
-
 	if (policy_is_shared(policy))
 		uu = sugov_update_shared;
 	else if (policy->fast_switch_enabled && cpufreq_driver_has_adjust_perf())
@@ -784,6 +776,10 @@ static int sugov_start(struct cpufreq_policy *policy)
 	for_each_cpu(cpu, policy->cpus) {
 		struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 
+		memset(sg_cpu, 0, sizeof(*sg_cpu));
+		sg_cpu->cpu			= cpu;
+		sg_cpu->sg_policy		= sg_policy;
+
 		cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu);
 	}
 	return 0;
-- 
2.25.1