[PATCH rcu 13/20] srcu: Move ->sda_is_static from srcu_struct to srcu_usage

From: Paul E. McKenney
Date: Thu Mar 30 2023 - 18:48:53 EST


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 <hch@xxxxxx>
Tested-by: Sachin Sant <sachinp@xxxxxxxxxxxxx>
Tested-by: "Zhang, Qiang1" <qiang1.zhang@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
include/linux/srcutree.h | 2 +-
kernel/rcu/srcutree.c | 8 ++++----
2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 3023492d8d89..d3534ecb806e 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 291fb520bce0..20f2373f7e25 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);
@@ -1906,7 +1906,7 @@ static void srcu_module_going(struct module *mod)
for (i = 0; i < mod->num_srcu_structs; i++) {
ssp = *(sspp++);
if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_sup->srcu_gp_seq_needed)) &&
- !WARN_ON_ONCE(!ssp->sda_is_static))
+ !WARN_ON_ONCE(!ssp->srcu_sup->sda_is_static))
cleanup_srcu_struct(ssp);
free_percpu(ssp->sda);
}
--
2.40.0.rc2