From: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Date: Mon, 22 Apr 2013 22:02:14 +0000 (-0700)
Subject: rcu: Expedite during suspend and resume only on smallish systems
X-Git-Tag: next-20130607~35^2~8
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e2c5c2b940456705cf6141e78f929b7a2d5e3c0b;p=karo-tx-linux.git

rcu: Expedite during suspend and resume only on smallish systems

Expedited grace periods are of dubious benefit on very large systems,
so this commit restricts their automated use during suspend and resume
to systems of 256 or fewer CPUs.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 45971118b445..00d4de0102f7 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -3009,7 +3009,8 @@ static int rcu_pm_notify(struct notifier_block *self,
 {
 	switch (action) {
 	case PM_HIBERNATION_PREPARE:
-		rcu_expedited = 1;
+		if (nr_cpu_ids <= 256) /* Expediting bad for large systems. */
+			rcu_expedited = 1;
 		break;
 	case PM_POST_RESTORE:
 		rcu_expedited = 0;