From 33136d12be00596a8320d4fe88f95c44f67afbdb Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
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 <daniel.turull@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
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);
--
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