From bbdacdfed2f5fa50a2cc9f500a36e05990a0837d Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 10 Aug 2017 17:10:26 +0200
Subject: sched/debug: Optimize sched_domain sysctl generation

Currently we unconditionally destroy all sysctl bits and regenerate
them after we've rebuild the domains (even if that rebuild is a
no-op).

And since we unconditionally (re)build the sysctl for all possible
CPUs, onlining all CPUs gets us O(n^2) time. Instead change this to
only rebuild the bits for CPUs we've actually installed new domains
on.

Reported-by: Ofer Levi(SW) <oferle@mellanox.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/sched.h | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'kernel/sched/sched.h')

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index eeef1a3086d1..25e5cb1107f3 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1120,11 +1120,15 @@ extern int group_balance_cpu(struct sched_group *sg);
 
 #if defined(CONFIG_SCHED_DEBUG) && defined(CONFIG_SYSCTL)
 void register_sched_domain_sysctl(void);
+void dirty_sched_domain_sysctl(int cpu);
 void unregister_sched_domain_sysctl(void);
 #else
 static inline void register_sched_domain_sysctl(void)
 {
 }
+static inline void dirty_sched_domain_sysctl(int cpu)
+{
+}
 static inline void unregister_sched_domain_sysctl(void)
 {
 }
-- 
cgit