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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-07-02 19:13:24 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-07-08 00:13:44 +0200 |
| commit | b58cc46c5f6b57f1c814e374dbc47176e6b4938e (patch) | |
| tree | da592215d7ebbd15cdb0773770cd45ed91c538d2 /kernel | |
| parent | rcu: Parallelize and economize NOCB kthread wakeups (diff) | |
| download | linux-b58cc46c5f6b57f1c814e374dbc47176e6b4938e.tar.xz linux-b58cc46c5f6b57f1c814e374dbc47176e6b4938e.zip | |
rcu: Don't offload callbacks unless specifically requested
Enabling NO_HZ_FULL currently has the side effect of enabling callback
offloading on all CPUs. This results in lots of additional rcuo kthreads,
and can also increase context switching and wakeups, even in cases where
callback offloading is neither needed nor particularly desirable. This
commit therefore enables callback offloading on a given CPU only if
specifically requested at build time or boot time, or if that CPU has
been specifically designated (again, either at build time or boot time)
as a nohz_full CPU.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index b27b86c7bbfa..17eed0856b03 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2473,6 +2473,9 @@ static void __init rcu_spawn_nocb_kthreads(struct rcu_state *rsp) if (rcu_nocb_mask == NULL) return; +#ifdef CONFIG_NO_HZ_FULL + cpumask_or(rcu_nocb_mask, rcu_nocb_mask, tick_nohz_full_mask); +#endif /* #ifdef CONFIG_NO_HZ_FULL */ if (ls == -1) { ls = int_sqrt(nr_cpu_ids); rcu_nocb_leader_stride = ls; |