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refscale: Add SRCU-fast-updown readers

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This commit adds refscale readers based on srcu_read_lock_fast_updown()
and srcu_read_unlock_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>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: <bpf@vger.kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
This commit is contained in:
Paul E. McKenney 2025-11-02 14:49:48 -08:00 committed by Frederic Weisbecker
parent 81f00c462e
commit bfad33230a
1 changed files with 39 additions and 1 deletions
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40
kernel/rcu/refscale.c
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@ -185,6 +185,7 @@ 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)
@ -253,6 +254,42 @@ 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.
@ -1170,7 +1207,8 @@ 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, &rwlock_ops, &rwsem_ops, &lock_ops, &lock_irq_ops,
&acqrel_ops, &sched_clock_ops, &clock_ops, &jiffies_ops,
&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,