From ebda37c27d0c768947e9b058332d7ea798210cf8 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 6 May 2010 23:51:21 +0000 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- net/core/dev.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index 988e42912e72..cdcb9cbedf41 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -2432,8 +2432,10 @@ static int enqueue_to_backlog(struct sk_buff *skb, int cpu, 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); }