* [PATCH net-next] net: sched: pie: avoid slow division in drop probability decay
@ 2019-02-28 12:36 Leslie Monis
2019-02-28 18:35 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Leslie Monis @ 2019-02-28 12:36 UTC (permalink / raw)
To: davem; +Cc: netdev, tahiliani, dave.taht, Leslie Monis
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 <David.Laight@aculab.com>
Signed-off-by: Leslie Monis <lesliemonis@gmail.com>
---
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;
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net-next] net: sched: pie: avoid slow division in drop probability decay
2019-02-28 12:36 [PATCH net-next] net: sched: pie: avoid slow division in drop probability decay Leslie Monis
@ 2019-02-28 18:35 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2019-02-28 18:35 UTC (permalink / raw)
To: lesliemonis; +Cc: netdev, tahiliani, dave.taht
From: Leslie Monis <lesliemonis@gmail.com>
Date: Thu, 28 Feb 2019 18:06:54 +0530
> 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 <David.Laight@aculab.com>
> Signed-off-by: Leslie Monis <lesliemonis@gmail.com>
Applied.
^ permalink raw reply [flat|nested] 2+ messages in thread
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