Commit-ID: b17c7035f37f47c7f7cb08a5555ab2aebfa31f91 Gitweb: http://git.kernel.org/tip/b17c7035f37f47c7f7cb08a5555ab2aebfa31f91 Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> AuthorDate: Thu, 6 Sep 2012 15:38:02 -0700 Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> CommitDate: Sun, 23 Sep 2012 07:41:56 -0700 rcu: Shrink RCU based on number of CPUs Currently, rcu_init_geometry() only reshapes RCU's combining trees if the leaf fanout is changed at boot time. This means that by default, kernels compiled with (say) NR_CPUS=4096 will keep oversized data structures, even when running on systems with (say) four CPUs. This commit therefore checks to see if the maximum number of CPUs on the actual running system (nr_cpu_ids) differs from NR_CPUS, and if so reshapes the combining trees accordingly. Reported-by: Mike Galbraith <efault@xxxxxx> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> --- kernel/rcutree.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 8b9496f..b703989 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -2821,7 +2821,8 @@ static void __init rcu_init_geometry(void) int rcu_capacity[MAX_RCU_LVLS + 1]; /* If the compile-time values are accurate, just leave. */ - if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF) + if (rcu_fanout_leaf == CONFIG_RCU_FANOUT_LEAF && + nr_cpu_ids == NR_CPUS) return; /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|