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Date: Thu, 23 Mar 2023 17:19:32 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: rcu@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, kernel-team@...a.com,
rostedt@...dmis.org, hch@....de,
"Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH RFC rcu 13/19] srcu: Move srcu_barrier() fields from srcu_struct to srcu_usage
This commit moves the ->srcu_barrier_seq, ->srcu_barrier_mutex,
->srcu_barrier_completion, and ->srcu_barrier_cpu_cnt fields 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@....de>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
include/linux/srcutree.h | 14 +++++++-------
kernel/rcu/srcutree.c | 38 +++++++++++++++++++-------------------
2 files changed, 26 insertions(+), 26 deletions(-)
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index ca48b97d9f3b..70f5a3abe80a 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -77,6 +77,13 @@ struct srcu_usage {
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()? */
+ unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */
+ struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */
+ struct completion srcu_barrier_completion;
+ /* Awaken barrier rq at end. */
+ atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */
+ /* callback for the barrier */
+ /* operation. */
};
/*
@@ -85,13 +92,6 @@ struct srcu_usage {
struct srcu_struct {
unsigned int srcu_idx; /* Current rdr array element. */
struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */
- unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */
- struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */
- struct completion srcu_barrier_completion;
- /* Awaken barrier rq at end. */
- atomic_t srcu_barrier_cpu_cnt; /* # CPUs not yet posting a */
- /* callback for the barrier */
- /* operation. */
unsigned long reschedule_jiffies;
unsigned long reschedule_count;
struct delayed_work work;
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index 7c192f7fb559..1df4a1467765 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -248,9 +248,9 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
mutex_init(&ssp->srcu_sup->srcu_gp_mutex);
ssp->srcu_idx = 0;
ssp->srcu_sup->srcu_gp_seq = 0;
- ssp->srcu_barrier_seq = 0;
- mutex_init(&ssp->srcu_barrier_mutex);
- atomic_set(&ssp->srcu_barrier_cpu_cnt, 0);
+ ssp->srcu_sup->srcu_barrier_seq = 0;
+ mutex_init(&ssp->srcu_sup->srcu_barrier_mutex);
+ atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0);
INIT_DELAYED_WORK(&ssp->work, process_srcu);
ssp->srcu_sup->sda_is_static = is_static;
if (!is_static)
@@ -1518,8 +1518,8 @@ static void srcu_barrier_cb(struct rcu_head *rhp)
sdp = container_of(rhp, struct srcu_data, srcu_barrier_head);
ssp = sdp->ssp;
- if (atomic_dec_and_test(&ssp->srcu_barrier_cpu_cnt))
- complete(&ssp->srcu_barrier_completion);
+ if (atomic_dec_and_test(&ssp->srcu_sup->srcu_barrier_cpu_cnt))
+ complete(&ssp->srcu_sup->srcu_barrier_completion);
}
/*
@@ -1533,13 +1533,13 @@ static void srcu_barrier_cb(struct rcu_head *rhp)
static void srcu_barrier_one_cpu(struct srcu_struct *ssp, struct srcu_data *sdp)
{
spin_lock_irq_rcu_node(sdp);
- atomic_inc(&ssp->srcu_barrier_cpu_cnt);
+ atomic_inc(&ssp->srcu_sup->srcu_barrier_cpu_cnt);
sdp->srcu_barrier_head.func = srcu_barrier_cb;
debug_rcu_head_queue(&sdp->srcu_barrier_head);
if (!rcu_segcblist_entrain(&sdp->srcu_cblist,
&sdp->srcu_barrier_head)) {
debug_rcu_head_unqueue(&sdp->srcu_barrier_head);
- atomic_dec(&ssp->srcu_barrier_cpu_cnt);
+ atomic_dec(&ssp->srcu_sup->srcu_barrier_cpu_cnt);
}
spin_unlock_irq_rcu_node(sdp);
}
@@ -1552,20 +1552,20 @@ void srcu_barrier(struct srcu_struct *ssp)
{
int cpu;
int idx;
- unsigned long s = rcu_seq_snap(&ssp->srcu_barrier_seq);
+ unsigned long s = rcu_seq_snap(&ssp->srcu_sup->srcu_barrier_seq);
check_init_srcu_struct(ssp);
- mutex_lock(&ssp->srcu_barrier_mutex);
- if (rcu_seq_done(&ssp->srcu_barrier_seq, s)) {
+ mutex_lock(&ssp->srcu_sup->srcu_barrier_mutex);
+ if (rcu_seq_done(&ssp->srcu_sup->srcu_barrier_seq, s)) {
smp_mb(); /* Force ordering following return. */
- mutex_unlock(&ssp->srcu_barrier_mutex);
+ mutex_unlock(&ssp->srcu_sup->srcu_barrier_mutex);
return; /* Someone else did our work for us. */
}
- rcu_seq_start(&ssp->srcu_barrier_seq);
- init_completion(&ssp->srcu_barrier_completion);
+ rcu_seq_start(&ssp->srcu_sup->srcu_barrier_seq);
+ init_completion(&ssp->srcu_sup->srcu_barrier_completion);
/* Initial count prevents reaching zero until all CBs are posted. */
- atomic_set(&ssp->srcu_barrier_cpu_cnt, 1);
+ atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 1);
idx = __srcu_read_lock_nmisafe(ssp);
if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
@@ -1576,12 +1576,12 @@ void srcu_barrier(struct srcu_struct *ssp)
__srcu_read_unlock_nmisafe(ssp, idx);
/* Remove the initial count, at which point reaching zero can happen. */
- if (atomic_dec_and_test(&ssp->srcu_barrier_cpu_cnt))
- complete(&ssp->srcu_barrier_completion);
- wait_for_completion(&ssp->srcu_barrier_completion);
+ if (atomic_dec_and_test(&ssp->srcu_sup->srcu_barrier_cpu_cnt))
+ complete(&ssp->srcu_sup->srcu_barrier_completion);
+ wait_for_completion(&ssp->srcu_sup->srcu_barrier_completion);
- rcu_seq_end(&ssp->srcu_barrier_seq);
- mutex_unlock(&ssp->srcu_barrier_mutex);
+ rcu_seq_end(&ssp->srcu_sup->srcu_barrier_seq);
+ mutex_unlock(&ssp->srcu_sup->srcu_barrier_mutex);
}
EXPORT_SYMBOL_GPL(srcu_barrier);
--
2.40.0.rc2
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