On 07/16/2014 08:45 AM, Paul E. McKenney wrote:
> On Tue, Jul 15, 2014 at 06:31:49PM -0400, Pranith Kumar wrote:
>> NUM_RCU_NODES is set at build time and is usually a huge number. We
>> calculate the
>> actual number of rcu nodes necessary at boot time based on nr_cpu_ids in
>> rcu_init_geometry() and store it in rcu_num_nodes. We should use this
>> variable
>> instead of NUM_RCU_NODES.
>>
>> This commit changes all such uses of NUM_RCU_NODES to rcu_num_nodes.
>>
>> Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
>> ---
>> kernel/rcu/tree_plugin.h | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
>> index cedb020..17ccb62 100644
>> --- a/kernel/rcu/tree_plugin.h
>> +++ b/kernel/rcu/tree_plugin.h
>> @@ -46,6 +46,8 @@ static bool __read_mostly rcu_nocb_poll; /* Offload
>> kthread are to poll. */
>> static char __initdata nocb_buf[NR_CPUS * 5];
>> #endif /* #ifdef CONFIG_RCU_NOCB_CPU */
>>
>> +extern int rcu_num_nodes;
>
> This should not be necessary given the existing declaration in
> kernel/rcu/tree.c way before the #include of kernel/rcu/tree_plugin.h.
>
> Or did you get a build failure without this? (And if you did get a build
> failure, I would be really curious how that happened!)
>
> So please send an updated patch or tell me how your build managed to fail.
>
Indeed. The extern was unnecessary. Please find an updated patch below.
--
Pranith
From: Pranith Kumar <bobby.pr...@gmail.com>
Date: Wed, 16 Jul 2014 09:21:49 -0400
Subject: [PATCH 1/1] rcu: Use rcu_num_nodes instead of NUM_RCU_NODES
NUM_RCU_NODES is set at build time and is usually a huge number. We calculate
the
actual number of rcu nodes necessary at boot time based on nr_cpu_ids in
rcu_init_geometry() and store it in rcu_num_nodes. We should use this variable
instead of NUM_RCU_NODES.
This commit changes all such uses of NUM_RCU_NODES to rcu_num_nodes.
Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
---
kernel/rcu/tree_plugin.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index cedb020..b99055a 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -885,7 +885,7 @@ void synchronize_rcu_expedited(void)
/* Snapshot current state of ->blkd_tasks lists. */
rcu_for_each_leaf_node(rsp, rnp)
sync_rcu_preempt_exp_init(rsp, rnp);
- if (NUM_RCU_NODES > 1)
+ if (rcu_num_nodes > 1)
sync_rcu_preempt_exp_init(rsp, rcu_get_root(rsp));
put_online_cpus();
@@ -1475,7 +1475,7 @@ static void __init rcu_spawn_boost_kthreads(void)
BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));
rnp = rcu_get_root(rcu_state_p);
(void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
- if (NUM_RCU_NODES > 1) {
+ if (rcu_num_nodes > 1) {
rcu_for_each_leaf_node(rcu_state_p, rnp)
(void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);
}
--
1.9.1
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