[RFC,12/19] srcu: Move ->sda_is_static from srcu_struct to srcu_usage

Commit Message

Paul E. McKenney March 24, 2023, 12:19 a.m. UTC

This commit moves the ->sda_is_static 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 <[e-mail]>
Signed-off-by: Paul E. McKenney <[e-mail]>
---
 include/linux/srcutree.h | 2 +-
 kernel/rcu/srcutree.c    | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

Patch

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 82d07466da93..ca48b97d9f3b 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -76,6 +76,7 @@  struct srcu_usage {
 	unsigned long srcu_size_jiffies;	/* Current contention-measurement interval. */
 	unsigned long srcu_n_lock_retries;	/* Contention events in current interval. */
 	unsigned long srcu_n_exp_nodelay;	/* # expedited no-delays in current GP phase. */
+	bool sda_is_static;			/* May ->sda be passed to free_percpu()? */
 };
 
 /*
@@ -84,7 +85,6 @@  struct srcu_usage {
 struct srcu_struct {
 	unsigned int srcu_idx;			/* Current rdr array element. */
 	struct srcu_data __percpu *sda;		/* Per-CPU srcu_data array. */
-	bool sda_is_static;			/* May ->sda be passed to free_percpu()? */
 	unsigned long srcu_barrier_seq;		/* srcu_barrier seq #. */
 	struct mutex srcu_barrier_mutex;	/* Serialize barrier ops. */
 	struct completion srcu_barrier_completion;
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 3f389b3a25aa..7c192f7fb559 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -252,7 +252,7 @@  static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
 	mutex_init(&ssp->srcu_barrier_mutex);
 	atomic_set(&ssp->srcu_barrier_cpu_cnt, 0);
 	INIT_DELAYED_WORK(&ssp->work, process_srcu);
-	ssp->sda_is_static = is_static;
+	ssp->srcu_sup->sda_is_static = is_static;
 	if (!is_static)
 		ssp->sda = alloc_percpu(struct srcu_data);
 	if (!ssp->sda) {
@@ -265,7 +265,7 @@  static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
 	ssp->srcu_sup->srcu_last_gp_end = ktime_get_mono_fast_ns();
 	if (READ_ONCE(ssp->srcu_sup->srcu_size_state) == SRCU_SIZE_SMALL && SRCU_SIZING_IS_INIT()) {
 		if (!init_srcu_struct_nodes(ssp, GFP_ATOMIC)) {
-			if (!ssp->sda_is_static) {
+			if (!ssp->srcu_sup->sda_is_static) {
 				free_percpu(ssp->sda);
 				ssp->sda = NULL;
 				kfree(ssp->srcu_sup);
@@ -667,7 +667,7 @@  void cleanup_srcu_struct(struct srcu_struct *ssp)
 	kfree(ssp->srcu_sup->node);
 	ssp->srcu_sup->node = NULL;
 	ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
-	if (!ssp->sda_is_static) {
+	if (!ssp->srcu_sup->sda_is_static) {
 		free_percpu(ssp->sda);
 		ssp->sda = NULL;
 		kfree(ssp->srcu_sup);