Commit 057df3ea authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Frederic Weisbecker
Browse files

refscale: Add preempt_disable() readers 



This commit adds refscale readers based on preempt_disable() and
preempt_enable() ("refscale.scale_type=preempt").  On my x86 laptop, these
are about 2.8ns.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
parent 78a731ce

kernel/rcu/refscale.c

+32 −1
Original line number Diff line number Diff line
@@ -629,6 +629,37 @@ static const struct ref_scale_ops jiffies_ops = { 
	.name		= "jiffies"

};



static void ref_preempt_section(const int nloops)

{

	int i;



	migrate_disable();

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

		preempt_disable();

		preempt_enable();

	}

	migrate_enable();

}



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

{

	int i;



	migrate_disable();

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

		preempt_disable();

		un_delay(udl, ndl);

		preempt_enable();

	}

	migrate_enable();

}



static const struct ref_scale_ops preempt_ops = {

	.readsection	= ref_preempt_section,

	.delaysection	= ref_preempt_delay_section,

	.name		= "preempt"

};



static void ref_bh_section(const int nloops)

{

	int i;
@@ -1261,7 +1292,7 @@ ref_scale_init(void) 
		&rcu_ops, &srcu_ops, &srcu_fast_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,

		&bh_ops, &irq_ops, &irqsave_ops,

		&preempt_ops, &bh_ops, &irq_ops, &irqsave_ops,

		&typesafe_ref_ops, &typesafe_lock_ops, &typesafe_seqlock_ops,

	};