rcu: Move RCU grace-period initialization into a kthread
As the first step towards allowing grace-period initialization to be
preemptible, this commit moves the RCU grace-period initialization
into its own kthread. This is needed to keep large-system scheduling
latency at reasonable levels.
Also change raw_spin_lock_irqsave() to raw_spin_lock_irq() as suggested
by Peter Zijlstra in review comments.
Reported-by: Mike Galbraith <mgalbraith@suse.de>
Reported-by: Dimitri Sivanich <sivanich@sgi.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 4d29169..117a150 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -385,6 +385,9 @@
u8 boost; /* Subject to priority boost. */
unsigned long gpnum; /* Current gp number. */
unsigned long completed; /* # of last completed gp. */
+ struct task_struct *gp_kthread; /* Task for grace periods. */
+ wait_queue_head_t gp_wq; /* Where GP task waits. */
+ int gp_flags; /* Commands for GP task. */
/* End of fields guarded by root rcu_node's lock. */
