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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-04-23 15:52:53 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-07-02 12:33:20 -0700
commitf885b7f2b2de70be266d2cecc476f773a1e2ca5d (patch)
treec4f4d03ca1469f22701b848274034a74c5ae2b04 /kernel/rcutree_plugin.h
parentcba6d0d64ee53772b285d0c0c288deefbeaf7775 (diff)
rcu: Control RCU_FANOUT_LEAF from boot-time parameter
Although making RCU_FANOUT_LEAF a kernel configuration parameter rather than a fixed constant makes it easier for people to decrease cache-miss overhead for large systems, it is of little help for people who must run a single pre-built kernel binary. This commit therefore allows the value of RCU_FANOUT_LEAF to be increased (but not decreased!) via a boot-time parameter named rcutree.rcu_fanout_leaf. Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree_plugin.h')
-rw-r--r--kernel/rcutree_plugin.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 3e4899459f3d..fb92b6dd9980 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -70,6 +70,8 @@ static void __init rcu_bootup_announce_oddness(void)
#if NUM_RCU_LVL_4 != 0
printk(KERN_INFO "\tExperimental four-level hierarchy is enabled.\n");
#endif
+ if (rcu_fanout_leaf != CONFIG_RCU_FANOUT_LEAF)
+ printk(KERN_INFO "\tExperimental boot-time adjustment of leaf fanout to %d.\n", rcu_fanout_leaf);
}
#ifdef CONFIG_TREE_PREEMPT_RCU