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Commit e800879d authored by Christoph Lameter's avatar Christoph Lameter Committed by Tejun Heo
Browse files

this_cpu: Use this_cpu operations in RCU 



RCU does not do dynamic allocations but it increments per cpu variables
a lot. These instructions results in a move to a register and then back
to memory. This patch will make it use the inc/dec instructions on x86
that do not need a register.

Acked-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 4dac3e98

kernel/rcutorture.c

+4 −4
Original line number Diff line number Diff line
@@ -731,13 +731,13 @@ static void rcu_torture_timer(unsigned long unused) 
		/* Should not happen, but... */

		pipe_count = RCU_TORTURE_PIPE_LEN;

	}

	++__get_cpu_var(rcu_torture_count)[pipe_count];

	__this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);

	completed = cur_ops->completed() - completed;

	if (completed > RCU_TORTURE_PIPE_LEN) {

		/* Should not happen, but... */

		completed = RCU_TORTURE_PIPE_LEN;

	}

	++__get_cpu_var(rcu_torture_batch)[completed];

	__this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);

	preempt_enable();

	cur_ops->readunlock(idx);

}
@@ -786,13 +786,13 @@ rcu_torture_reader(void *arg) 
			/* Should not happen, but... */

			pipe_count = RCU_TORTURE_PIPE_LEN;

		}

		++__get_cpu_var(rcu_torture_count)[pipe_count];

		__this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);

		completed = cur_ops->completed() - completed;

		if (completed > RCU_TORTURE_PIPE_LEN) {

			/* Should not happen, but... */

			completed = RCU_TORTURE_PIPE_LEN;

		}

		++__get_cpu_var(rcu_torture_batch)[completed];

		__this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);

		preempt_enable();

		cur_ops->readunlock(idx);

		schedule();