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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-04-24 00:52:53 +0200
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-07-02 21:33:20 +0200
commitf885b7f2b2de70be266d2cecc476f773a1e2ca5d (patch)
treec4f4d03ca1469f22701b848274034a74c5ae2b04 /Documentation/kernel-parameters.txt
parentRevert "rcu: Move PREEMPT_RCU preemption to switch_to() invocation" (diff)
downloadlinux-f885b7f2b2de70be266d2cecc476f773a1e2ca5d.tar.xz
linux-f885b7f2b2de70be266d2cecc476f773a1e2ca5d.zip
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 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt5
1 files changed, 5 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a92c5ebf373e..12783fa833c3 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2367,6 +2367,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Set maximum number of finished RCU callbacks to process
in one batch.
+ rcutree.fanout_leaf= [KNL,BOOT]
+ Increase the number of CPUs assigned to each
+ leaf rcu_node structure. Useful for very large
+ systems.
+
rcutree.qhimark= [KNL,BOOT]
Set threshold of queued
RCU callbacks over which batch limiting is disabled.