diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2009-12-02 12:10:14 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-12-03 11:34:53 +0100 |
| commit | cf244dc01bf68e1ad338b82447f8686d24ea4435 (patch) | |
| tree | dc2aebb60ef1eddf92d7e23b72ec2f6c08797684 /kernel/rcutree.c | |
| parent | d3f6bad3911736e44ba11f3f3f6ac4e8c837fdfc (diff) | |
rcu: Enable fourth level of TREE_RCU hierarchy
Enable a fourth level of rcu_node hierarchy for TREE_RCU and
TREE_PREEMPT_RCU. This is for stress-testing and experiemental
purposes only, although in theory this would enable 16,777,216
CPUs on 64-bit systems, though only 1,048,576 CPUs on 32-bit
systems. Normal experimental use of this fourth level will
normally set CONFIG_RCU_FANOUT=2, requiring a 16-CPU system,
though the more adventurous (and more fortunate) experimenters
may wish to chose CONFIG_RCU_FANOUT=3 for 81-CPU systems or even
CONFIG_RCU_FANOUT=4 for 256-CPU systems.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Josh Triplett <josh@joshtriplett.org>
Acked-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <12597846161257-git-send-email->
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.c')
| -rw-r--r-- | kernel/rcutree.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index a9f51031d3e8..d47e03e5792a 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -60,7 +60,8 @@ static struct lock_class_key rcu_node_class[NUM_RCU_LVLS]; NUM_RCU_LVL_0, /* root of hierarchy. */ \ NUM_RCU_LVL_1, \ NUM_RCU_LVL_2, \ - NUM_RCU_LVL_3, /* == MAX_RCU_LVLS */ \ + NUM_RCU_LVL_3, \ + NUM_RCU_LVL_4, /* == MAX_RCU_LVLS */ \ }, \ .signaled = RCU_GP_IDLE, \ .gpnum = -300, \ @@ -1877,6 +1878,9 @@ void __init rcu_init(void) #ifdef CONFIG_RCU_CPU_STALL_DETECTOR printk(KERN_INFO "RCU-based detection of stalled CPUs is enabled.\n"); #endif /* #ifdef CONFIG_RCU_CPU_STALL_DETECTOR */ +#if NUM_RCU_LVL_4 != 0 + printk(KERN_INFO "Experimental four-level hierarchy is enabled.\n"); +#endif /* #if NUM_RCU_LVL_4 != 0 */ RCU_INIT_FLAVOR(&rcu_sched_state, rcu_sched_data); RCU_INIT_FLAVOR(&rcu_bh_state, rcu_bh_data); __rcu_init_preempt(); |