Commit 25f6fa53 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

refscale: Add measurement of clock readout 



This commit adds a "clock" type to refscale, which checks the performance
of ktime_get_real_fast_ns().  Use the "clocksource=" kernel boot parameter
to select the underlying clock source.

[ paulmck: Work around compiler false positive per kernel test robot. ]
Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent 2734d6c1

kernel/rcu/refscale.c

+35 −1
Original line number Diff line number Diff line
@@ -467,6 +467,40 @@ static struct ref_scale_ops acqrel_ops = { 
	.name		= "acqrel"

};



static volatile u64 stopopts;



static void ref_clock_section(const int nloops)

{

	u64 x = 0;

	int i;



	preempt_disable();

	for (i = nloops; i >= 0; i--)

		x += ktime_get_real_fast_ns();

	preempt_enable();

	stopopts = x;

}



static void ref_clock_delay_section(const int nloops, const int udl, const int ndl)

{

	u64 x = 0;

	int i;



	preempt_disable();

	for (i = nloops; i >= 0; i--) {

		x += ktime_get_real_fast_ns();

		un_delay(udl, ndl);

	}

	preempt_enable();

	stopopts = x;

}



static struct ref_scale_ops clock_ops = {

	.readsection	= ref_clock_section,

	.delaysection	= ref_clock_delay_section,

	.name		= "clock"

};



static void rcu_scale_one_reader(void)

{

	if (readdelay <= 0)
@@ -759,7 +793,7 @@ ref_scale_init(void) 
	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, &lock_ops, &lock_irq_ops, &acqrel_ops,

		&rwsem_ops, &lock_ops, &lock_irq_ops, &acqrel_ops, &clock_ops,

	};



	if (!torture_init_begin(scale_type, verbose))