Commit bfad3323 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Frederic Weisbecker
Browse files

refscale: Add SRCU-fast-updown readers 



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: default avatarPaul 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: default avatarFrederic Weisbecker <frederic@kernel.org>
parent 81f00c46

kernel/rcu/refscale.c

+39 −1
Original line number Diff line number Diff line
@@ -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,