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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-06-22 17:06:26 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-09-23 07:41:54 -0700
commit4cdfc175c25c89eedc08460b5e6239c2ec67fcb6 (patch)
tree716acd208cb0633cdd19fc0cd5ad601906cceb24 /kernel/rcutree.h
parentb402b73b3afe3614bc0e921ebe18013ea103115a (diff)
rcu: Move quiescent-state forcing into kthread
As the first step towards allowing quiescent-state forcing to be preemptible, this commit moves RCU quiescent-state forcing into the same kthread that is now used to initialize and clean up after grace periods. This is yet another step towards keeping scheduling latency down to a dull roar. Updated to change from raw_spin_lock_irqsave() to raw_spin_lock_irq() and to remove the now-unused rcu_state structure fields as suggested by Peter Zijlstra. 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>
Diffstat (limited to 'kernel/rcutree.h')
-rw-r--r--kernel/rcutree.h13
1 files changed, 4 insertions, 9 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 5d92b80a0a28..2d04106d1533 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -378,13 +378,6 @@ struct rcu_state {
u8 fqs_state ____cacheline_internodealigned_in_smp;
/* Force QS state. */
- u8 fqs_active; /* force_quiescent_state() */
- /* is running. */
- u8 fqs_need_gp; /* A CPU was prevented from */
- /* starting a new grace */
- /* period because */
- /* force_quiescent_state() */
- /* was running. */
u8 boost; /* Subject to priority boost. */
unsigned long gpnum; /* Current gp number. */
unsigned long completed; /* # of last completed gp. */
@@ -413,8 +406,6 @@ struct rcu_state {
struct completion barrier_completion; /* Wake at barrier end. */
unsigned long n_barrier_done; /* ++ at start and end of */
/* _rcu_barrier(). */
- raw_spinlock_t fqslock; /* Only one task forcing */
- /* quiescent states. */
unsigned long jiffies_force_qs; /* Time at which to invoke */
/* force_quiescent_state(). */
unsigned long n_force_qs; /* Number of calls to */
@@ -433,6 +424,10 @@ struct rcu_state {
struct list_head flavors; /* List of RCU flavors. */
};
+/* Values for rcu_state structure's gp_flags field. */
+#define RCU_GP_FLAG_INIT 0x1 /* Need grace-period initialization. */
+#define RCU_GP_FLAG_FQS 0x2 /* Need grace-period quiescent-state forcing. */
+
extern struct list_head rcu_struct_flavors;
#define for_each_rcu_flavor(rsp) \
list_for_each_entry((rsp), &rcu_struct_flavors, flavors)