This commit moves the ->srcu_cb_mutex field from the srcu_struct structure
to the srcu_usage structure to reduce the size of the former in order
to improve cache locality.
Suggested-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
include/linux/srcutree.h | 2 +-
kernel/rcu/srcutree.c | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 72fb01fb2eb5..69d49de87b67 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -65,13 +65,13 @@ struct srcu_usage {
struct srcu_node *level[RCU_NUM_LVLS + 1];
/* First node at each level. */
int srcu_size_state; /* Small-to-big transition state. */
+ struct mutex srcu_cb_mutex; /* Serialize CB preparation. */
};
/*
* Per-SRCU-domain structure, similar in function to rcu_state.
*/
struct srcu_struct {
- struct mutex srcu_cb_mutex; /* Serialize CB preparation. */
spinlock_t __private lock; /* Protect counters and size state. */
struct mutex srcu_gp_mutex; /* Serialize GP work. */
unsigned int srcu_idx; /* Current rdr array element. */
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 2717217de136..6b6d92fe41cf 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -242,7 +242,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
return -ENOMEM;
ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
ssp->srcu_sup->node = NULL;
- mutex_init(&ssp->srcu_cb_mutex);
+ mutex_init(&ssp->srcu_sup->srcu_cb_mutex);
mutex_init(&ssp->srcu_gp_mutex);
ssp->srcu_idx = 0;
ssp->srcu_gp_seq = 0;
@@ -861,7 +861,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
int ss_state;
/* Prevent more than one additional grace period. */
- mutex_lock(&ssp->srcu_cb_mutex);
+ mutex_lock(&ssp->srcu_sup->srcu_cb_mutex);
/* End the current grace period. */
spin_lock_irq_rcu_node(ssp);
@@ -921,7 +921,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
}
/* Callback initiation done, allow grace periods after next. */
- mutex_unlock(&ssp->srcu_cb_mutex);
+ mutex_unlock(&ssp->srcu_sup->srcu_cb_mutex);
/* Start a new grace period if needed. */
spin_lock_irq_rcu_node(ssp);
--
2.40.0.rc2
