linux-kernel - [GIT PULL] scheduler fix

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>] [day] [month] [year] [list]

Date:	Thu, 7 Apr 2011 19:38:01 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] scheduler fix

Linus,

Please pull the latest sched-fixes-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git sched-fixes-for-linus

 Thanks,

	Ingo

------------------>
Peter Zijlstra (1):
      sched: Clean up rebalance_domains() load-balance interval calculation


 kernel/sched.c      |    3 +++
 kernel/sched_fair.c |   16 ++++++++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index a884551..17b4d22 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6331,6 +6331,9 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
 		break;
 #endif
 	}
+
+	update_max_interval();
+
 	return NOTIFY_OK;
 }
 
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index c7ec5c8..80ecd09 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -3820,6 +3820,17 @@ void select_nohz_load_balancer(int stop_tick)
 
 static DEFINE_SPINLOCK(balancing);
 
+static unsigned long __read_mostly max_load_balance_interval = HZ/10;
+
+/*
+ * Scale the max load_balance interval with the number of CPUs in the system.
+ * This trades load-balance latency on larger machines for less cross talk.
+ */
+static void update_max_interval(void)
+{
+	max_load_balance_interval = HZ*num_online_cpus()/10;
+}
+
 /*
  * It checks each scheduling domain to see if it is due to be balanced,
  * and initiates a balancing operation if so.
@@ -3849,10 +3860,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
 
 		/* scale ms to jiffies */
 		interval = msecs_to_jiffies(interval);
-		if (unlikely(!interval))
-			interval = 1;
-		if (interval > HZ*num_online_cpus()/10)
-			interval = HZ*num_online_cpus()/10;
+		interval = clamp(interval, 1UL, max_load_balance_interval);
 
 		need_serialize = sd->flags & SD_SERIALIZE;
 
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/