From 6c97da141528097eb8e1d532dc0dbe3501f4c8ff Mon Sep 17 00:00:00 2001 From: Leslie Monis Date: Thu, 28 Feb 2019 18:06:54 +0530 Subject: [PATCH] net: sched: pie: avoid slow division in drop probability decay As per RFC 8033, it is sufficient for the drop probability decay factor to have a value of (1 - 1/64) instead of 98%. This avoids the need to do slow division. Suggested-by: David Laight Signed-off-by: Leslie Monis Signed-off-by: David S. Miller --- net/sched/sch_pie.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c index f93cfe034c72..1cc0c7b74aa3 100644 --- a/net/sched/sch_pie.c +++ b/net/sched/sch_pie.c @@ -429,7 +429,8 @@ static void calculate_probability(struct Qdisc *sch) */ if (qdelay == 0 && qdelay_old == 0 && update_prob) - q->vars.prob = 98 * div_u64(q->vars.prob, 100); + /* Reduce drop probability to 98.4% */ + q->vars.prob -= q->vars.prob / 64u; q->vars.qdelay = qdelay; q->vars.qlen_old = qlen;