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Subject[tip: core/rcu] refscale: Add acqrel, lock, and lock-irq
The following commit has been merged into the core/rcu branch of tip:

Commit-ID: e9b800db96fa40170c5607d8968b2ec6212c2026
Gitweb: https://git.kernel.org/tip/e9b800db96fa40170c5607d8968b2ec6212c2026
Author: Paul E. McKenney <paulmck@kernel.org>
AuthorDate: Wed, 10 Mar 2021 18:02:36 -08:00
Committer: Paul E. McKenney <paulmck@kernel.org>
CommitterDate: Mon, 10 May 2021 16:05:05 -07:00

refscale: Add acqrel, lock, and lock-irq

This commit adds scale_type of acqrel, lock, and lock-irq to
test acquisition and release. Note that the refscale.nreaders=1
module parameter is required if you wish to test uncontended locking.
In contrast, acqrel uses a per-CPU variable, so should be just fine with
large values of the refscale.nreaders=1 module parameter.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
kernel/rcu/refscale.c | 109 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 107 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 02dd976..313d454 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -362,6 +362,111 @@ static struct ref_scale_ops rwsem_ops = {
.name = "rwsem"
};

+// Definitions for global spinlock
+static DEFINE_SPINLOCK(test_lock);
+
+static void ref_lock_section(const int nloops)
+{
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock(&test_lock);
+ spin_unlock(&test_lock);
+ }
+ preempt_enable();
+}
+
+static void ref_lock_delay_section(const int nloops, const int udl, const int ndl)
+{
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock(&test_lock);
+ un_delay(udl, ndl);
+ spin_unlock(&test_lock);
+ }
+ preempt_enable();
+}
+
+static struct ref_scale_ops lock_ops = {
+ .readsection = ref_lock_section,
+ .delaysection = ref_lock_delay_section,
+ .name = "lock"
+};
+
+// Definitions for global irq-save spinlock
+
+static void ref_lock_irq_section(const int nloops)
+{
+ unsigned long flags;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock_irqsave(&test_lock, flags);
+ spin_unlock_irqrestore(&test_lock, flags);
+ }
+ preempt_enable();
+}
+
+static void ref_lock_irq_delay_section(const int nloops, const int udl, const int ndl)
+{
+ unsigned long flags;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ spin_lock_irqsave(&test_lock, flags);
+ un_delay(udl, ndl);
+ spin_unlock_irqrestore(&test_lock, flags);
+ }
+ preempt_enable();
+}
+
+static struct ref_scale_ops lock_irq_ops = {
+ .readsection = ref_lock_irq_section,
+ .delaysection = ref_lock_irq_delay_section,
+ .name = "lock-irq"
+};
+
+// Definitions acquire-release.
+static DEFINE_PER_CPU(unsigned long, test_acqrel);
+
+static void ref_acqrel_section(const int nloops)
+{
+ unsigned long x;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
+ smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
+ }
+ preempt_enable();
+}
+
+static void ref_acqrel_delay_section(const int nloops, const int udl, const int ndl)
+{
+ unsigned long x;
+ int i;
+
+ preempt_disable();
+ for (i = nloops; i >= 0; i--) {
+ x = smp_load_acquire(this_cpu_ptr(&test_acqrel));
+ un_delay(udl, ndl);
+ smp_store_release(this_cpu_ptr(&test_acqrel), x + 1);
+ }
+ preempt_enable();
+}
+
+static struct ref_scale_ops acqrel_ops = {
+ .readsection = ref_acqrel_section,
+ .delaysection = ref_acqrel_delay_section,
+ .name = "acqrel"
+};
+
static void rcu_scale_one_reader(void)
{
if (readdelay <= 0)
@@ -653,8 +758,8 @@ ref_scale_init(void)
long i;
int firsterr = 0;
static struct ref_scale_ops *scale_ops[] = {
- &rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops,
- &refcnt_ops, &rwlock_ops, &rwsem_ops,
+ &rcu_ops, &srcu_ops, &rcu_trace_ops, &rcu_tasks_ops, &refcnt_ops, &rwlock_ops,
+ &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops,
};

if (!torture_init_begin(scale_type, verbose))
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