From 33136d12be00596a8320d4fe88f95c44f67afbdb Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 20 Oct 2011 17:00:21 -0400 Subject: [PATCH] pktgen: remove ndelay() call Daniel Turull reported inaccuracies in pktgen when using low packet rates, because we call ndelay(val) with values bigger than 20000. Instead of calling ndelay() for delays < 100us, we can instead loop calling ktime_now() only. Reported-by: Daniel Turull Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/core/pktgen.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/net/core/pktgen.c b/net/core/pktgen.c index 6bbf00801f61..0001c243b35c 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -2145,9 +2145,12 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until) } start_time = ktime_now(); - if (remaining < 100000) - ndelay(remaining); /* really small just spin */ - else { + if (remaining < 100000) { + /* for small delays (<100us), just loop until limit is reached */ + do { + end_time = ktime_now(); + } while (ktime_lt(end_time, spin_until)); + } else { /* see do_nanosleep */ hrtimer_init_sleeper(&t, current); do { @@ -2162,8 +2165,8 @@ static void spin(struct pktgen_dev *pkt_dev, ktime_t spin_until) hrtimer_cancel(&t.timer); } while (t.task && pkt_dev->running && !signal_pending(current)); __set_current_state(TASK_RUNNING); + end_time = ktime_now(); } - end_time = ktime_now(); pkt_dev->idle_acc += ktime_to_ns(ktime_sub(end_time, start_time)); pkt_dev->next_tx = ktime_add_ns(spin_until, pkt_dev->delay); -- 2.30.2