Commit ebda37c2 authored May 06, 2010 by Eric Dumazet Committed by David S. Miller May 17, 2010

rps: avoid one atomic in enqueue_to_backlog



If CONFIG_SMP=y, then we own a queue spinlock, we can avoid the atomic
test_and_set_bit() from napi_schedule_prep().

We now have same number of atomic ops per netif_rx() calls than with
pre-RPS kernel.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 3f78d1f2

net/core/dev.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -2432,8 +2432,10 @@ enqueue:
		return NET_RX_SUCCESS;
		}

		/* Schedule NAPI for backlog device */
		if (napi_schedule_prep(&sd->backlog)) {
		/* Schedule NAPI for backlog device
		* We can use non atomic operation since we own the queue lock
		*/
		if (!__test_and_set_bit(NAPI_STATE_SCHED, &sd->backlog.state)) {
		if (!rps_ipi_queued(sd))
		____napi_schedule(sd, &sd->backlog);
		}