linux-kernel - [tip: sched/core] sched/fair: Account update_blocked_averages in newidle

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 for Android: free password hash cracker in your pocket

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

Message-ID: <163567538702.626.3632817965971500674.tip-bot2@tip-bot2>
Date:   Sun, 31 Oct 2021 10:16:27 -0000
From:   "tip-bot2 for Vincent Guittot" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Mel Gorman <mgorman@...e.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Account update_blocked_averages in
 newidle_balance cost

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     9e9af819db5dbe4bf99101628955a26e2a41a1a5
Gitweb:        https://git.kernel.org/tip/9e9af819db5dbe4bf99101628955a26e2a41a1a5
Author:        Vincent Guittot <vincent.guittot@...aro.org>
AuthorDate:    Tue, 19 Oct 2021 14:35:33 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Sun, 31 Oct 2021 11:11:37 +01:00

sched/fair: Account update_blocked_averages in newidle_balance cost

The time spent to update the blocked load can be significant depending of
the complexity fo the cgroup hierarchy. Take this time into account in
the cost of the 1st load balance of a newly idle cpu.

Also reduce the number of call to sched_clock_cpu() and track more actual
work.

Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@....com>
Acked-by: Mel Gorman <mgorman@...e.de>
Link: https://lore.kernel.org/r/20211019123537.17146-2-vincent.guittot@linaro.org
---
 kernel/sched/fair.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 87db481..c014567 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10840,9 +10840,9 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
 {
 	unsigned long next_balance = jiffies + HZ;
 	int this_cpu = this_rq->cpu;
+	u64 t0, t1, curr_cost = 0;
 	struct sched_domain *sd;
 	int pulled_task = 0;
-	u64 curr_cost = 0;
 
 	update_misfit_status(NULL, this_rq);
 
@@ -10887,11 +10887,13 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
 
 	raw_spin_rq_unlock(this_rq);
 
+	t0 = sched_clock_cpu(this_cpu);
 	update_blocked_averages(this_cpu);
+
 	rcu_read_lock();
 	for_each_domain(this_cpu, sd) {
 		int continue_balancing = 1;
-		u64 t0, domain_cost;
+		u64 domain_cost;
 
 		if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) {
 			update_next_balance(sd, &next_balance);
@@ -10899,17 +10901,18 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
 		}
 
 		if (sd->flags & SD_BALANCE_NEWIDLE) {
-			t0 = sched_clock_cpu(this_cpu);
 
 			pulled_task = load_balance(this_cpu, this_rq,
 						   sd, CPU_NEWLY_IDLE,
 						   &continue_balancing);
 
-			domain_cost = sched_clock_cpu(this_cpu) - t0;
+			t1 = sched_clock_cpu(this_cpu);
+			domain_cost = t1 - t0;
 			if (domain_cost > sd->max_newidle_lb_cost)
 				sd->max_newidle_lb_cost = domain_cost;
 
 			curr_cost += domain_cost;
+			t0 = t1;
 		}
 
 		update_next_balance(sd, &next_balance);