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Message-ID: <20110407173801.GA24944@elte.hu>
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;
--
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