refscale: Add SRCU-fast-updown readers
This commit adds refscale readers based on srcu_read_lock_fast_updown()
and srcu_read_lock_fast_updown() ("refscale.scale_type=srcu-fast-updown").
On my x86 laptop, these are about 2.2ns per pair.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
diff --git a/kernel/rcu/refscale.c b/kernel/rcu/refscale.c
index 7429ec9..07a3137 100644
--- a/kernel/rcu/refscale.c
+++ b/kernel/rcu/refscale.c
@@ -186,6 +186,7 @@ static const struct ref_scale_ops rcu_ops = {
// Definitions for SRCU ref scale testing.
DEFINE_STATIC_SRCU(srcu_refctl_scale);
DEFINE_STATIC_SRCU_FAST(srcu_fast_refctl_scale);
+DEFINE_STATIC_SRCU_FAST_UPDOWN(srcu_fast_updown_refctl_scale);
static struct srcu_struct *srcu_ctlp = &srcu_refctl_scale;
static void srcu_ref_scale_read_section(const int nloops)
@@ -254,6 +255,42 @@ static const struct ref_scale_ops srcu_fast_ops = {
.name = "srcu-fast"
};
+static bool srcu_fast_updown_sync_scale_init(void)
+{
+ srcu_ctlp = &srcu_fast_updown_refctl_scale;
+ return true;
+}
+
+static void srcu_fast_updown_ref_scale_read_section(const int nloops)
+{
+ int i;
+ struct srcu_ctr __percpu *scp;
+
+ for (i = nloops; i >= 0; i--) {
+ scp = srcu_read_lock_fast_updown(srcu_ctlp);
+ srcu_read_unlock_fast_updown(srcu_ctlp, scp);
+ }
+}
+
+static void srcu_fast_updown_ref_scale_delay_section(const int nloops, const int udl, const int ndl)
+{
+ int i;
+ struct srcu_ctr __percpu *scp;
+
+ for (i = nloops; i >= 0; i--) {
+ scp = srcu_read_lock_fast_updown(srcu_ctlp);
+ un_delay(udl, ndl);
+ srcu_read_unlock_fast_updown(srcu_ctlp, scp);
+ }
+}
+
+static const struct ref_scale_ops srcu_fast_updown_ops = {
+ .init = srcu_fast_updown_sync_scale_init,
+ .readsection = srcu_fast_updown_ref_scale_read_section,
+ .delaysection = srcu_fast_updown_ref_scale_delay_section,
+ .name = "srcu-fast-updown"
+};
+
#ifdef CONFIG_TASKS_RCU
// Definitions for RCU Tasks ref scale testing: Empty read markers.
@@ -1479,7 +1516,8 @@ ref_scale_init(void)
long i;
int firsterr = 0;
static const struct ref_scale_ops *scale_ops[] = {
- &rcu_ops, &srcu_ops, &srcu_fast_ops, RCU_TRACE_OPS RCU_TASKS_OPS
+ &rcu_ops, &srcu_ops, &srcu_fast_ops, &srcu_fast_updown_ops,
+ RCU_TRACE_OPS RCU_TASKS_OPS
&refcnt_ops, &percpuinc_ops, &incpercpu_ops, &incpercpupreempt_ops,
&incpercpubh_ops, &incpercpuirqsave_ops,
&rwlock_ops, &rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops,
