Commit b5a2801f authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

refscale: Add a "jiffies" test 



This commit adds a "jiffies" test to refscale, allowing use of jiffies
to be compared to ktime_get_real_fast_ns().  On my x86 laptop, jiffies
is more than 20x faster.  (Though for many uses, the tens-of-nanoseconds
overhead of ktime_get_real_fast_ns() will be just fine.)

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
parent f5063e89

kernel/rcu/refscale.c

+33 −1
Original line number Diff line number Diff line
@@ -528,6 +528,38 @@ static struct ref_scale_ops clock_ops = { 
	.name		= "clock"

};



static void ref_jiffies_section(const int nloops)

{

	u64 x = 0;

	int i;



	preempt_disable();

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

		x += jiffies;

	preempt_enable();

	stopopts = x;

}



static void ref_jiffies_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 += jiffies;

		un_delay(udl, ndl);

	}

	preempt_enable();

	stopopts = x;

}



static struct ref_scale_ops jiffies_ops = {

	.readsection	= ref_jiffies_section,

	.delaysection	= ref_jiffies_delay_section,

	.name		= "jiffies"

};



////////////////////////////////////////////////////////////////////////

//

// Methods leveraging SLAB_TYPESAFE_BY_RCU.
@@ -1047,7 +1079,7 @@ 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, &clock_ops,

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

		&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,

	};