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Date: Sat, 15 Jan 2011 08:45:42 +0100
From: Eric Dumazet <eric.dumazet@...il.com>
To: Stephen Hemminger <shemminger@...tta.com>
Cc: Patrick McHardy <kaber@...sh.net>,
David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] CHOKe flow scheduler (0.9)
Le vendredi 14 janvier 2011 à 15:45 -0800, Stephen Hemminger a écrit :
> CHOKe ("CHOose and Kill" or "CHOose and Keep") is an alternative
> packet scheduler based on the Random Exponential Drop (RED) algorithm.
>
> The core idea is:
> For every packet arrival:
> Calculate Qave
> if (Qave < minth)
> Queue the new packet
> else
> Select randomly a packet from the queue
> if (both packets from same flow)
> then Drop both the packets
> else if (Qave > maxth)
> Drop packet
> else
> Admit packet with proability p (same as RED)
>
> See also:
> Rong Pan, Balaji Prabhakar, Konstantinos Psounis, "CHOKe: a stateless active
> queue management scheme for approximating fair bandwidth allocation",
> Proceeding of INFOCOM'2000, March 2000.
>
> Help from:
> Eric Dumazet <eric.dumazet@...il.com>
> Patrick McHardy <kaber@...sh.net>
>
> Signed-off-by: Stephen Hemminger <shemminger@...tta.com>
>
> ---
> This version is based on net-next, and assumes Eric's patch for
> corrected bstats is already applied.
>
> 0.9 incorporate patches from Patrick/Eric
> rework the peek_random and drop code to simplify and fix bug where
> random_N needs to called with full length (including holes).
Nice catch, I now have more "matched" counts after my test :
qdisc choke 11: parent 1:11 limit 130000b min 10833b max 32500b ewma 13 Plog 21 Scell_log 30
Sent 93944198 bytes 170889 pkt (dropped 829140, overlimits 436686 requeues 0)
rate 48bit 0pps backlog 0b 0p requeues 0
marked 0 early 436686 pdrop 0 other 0 matched 196227
You missed the qdisc_bstats_update() move from enqueue() to dequeue()
And some minor CodingStyle / checkpatch.pl changes, here is my
latest diff on top of 0.9
I believe you can release v1 :)
Thanks !
net/sched/sch_choke.c | 35 ++++++++++++++++++-----------------
1 files changed, 18 insertions(+), 17 deletions(-)
diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
index 55eeb7d..a7605a0 100644
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -20,7 +20,7 @@
#include <net/red.h>
/* CHOKe stateless AQM for fair bandwidth allocation
- =================================================
+ =================================================
CHOKe (CHOose and Keep for responsive flows, CHOose and Kill for
unresponsive flows) is a variant of RED that penalizes misbehaving flows but
@@ -137,10 +137,10 @@ static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx)
}
/* Classify flow using either:
- 1. pre-existing classification result in skb
- 2. fast internal classification
- 3. use TC filter based classification
-*/
+ * 1. pre-existing classification result in skb
+ * 2. fast internal classification (rxhash)
+ * 3. use TC filter based classification
+ */
static unsigned int choke_classify(struct sk_buff *skb,
struct Qdisc *sch, int *qerr)
@@ -176,10 +176,9 @@ static unsigned int choke_classify(struct sk_buff *skb,
}
/* Select a packet at random from the queue and return flow classification
- returns 0 if queue empty
+ * returns 0 if queue empty
*/
-static unsigned int choke_peek_random(struct Qdisc *sch,
- unsigned int *pidx)
+static unsigned int choke_peek_random(struct Qdisc *sch, unsigned int *pidx)
{
struct choke_sched_data *q = qdisc_priv(sch);
const struct sk_buff *skb;
@@ -229,9 +228,9 @@ static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch)
red_end_of_idle_period(p);
/* Is queue small? */
- if (p->qavg <= p->qth_min)
+ if (p->qavg <= p->qth_min) {
p->qcount = -1;
- else {
+ } else {
unsigned int idx;
/* Draw a packet at random from queue and compare flow */
@@ -266,8 +265,9 @@ static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch)
q->stats.prob_mark++;
}
- } else
+ } else {
p->qR = red_random(p);
+ }
}
/* Admit new packet */
@@ -276,7 +276,6 @@ static int choke_enqueue(struct sk_buff *skb, struct Qdisc *sch)
q->tail = (q->tail + 1) & q->tab_mask;
++sch->q.qlen;
sch->qstats.backlog += qdisc_pkt_len(skb);
- qdisc_bstats_update(sch, skb);
return NET_XMIT_SUCCESS;
}
@@ -306,6 +305,7 @@ static struct sk_buff *choke_dequeue(struct Qdisc *sch)
choke_zap_head_holes(q);
--sch->q.qlen;
sch->qstats.backlog -= qdisc_pkt_len(skb);
+ qdisc_bstats_update(sch, skb);
return skb;
}
@@ -316,9 +316,9 @@ static unsigned int choke_drop(struct Qdisc *sch)
unsigned int len;
len = qdisc_queue_drop(sch);
- if (len > 0)
+ if (len > 0) {
q->stats.other++;
- else {
+ } else {
if (!red_is_idling(&q->parms))
red_start_of_idle_period(&q->parms);
}
@@ -326,7 +326,7 @@ static unsigned int choke_drop(struct Qdisc *sch)
return len;
}
-static void choke_reset(struct Qdisc* sch)
+static void choke_reset(struct Qdisc *sch)
{
struct choke_sched_data *q = qdisc_priv(sch);
@@ -410,8 +410,9 @@ static int choke_change(struct Qdisc *sch, struct nlattr *opt)
q->tab_mask = mask;
q->tab = ntab;
- } else
+ } else {
sch_tree_lock(sch);
+ }
q->flags = ctl->flags;
q->limit = ctl->limit;
@@ -428,7 +429,7 @@ static int choke_change(struct Qdisc *sch, struct nlattr *opt)
return 0;
}
-static int choke_init(struct Qdisc* sch, struct nlattr *opt)
+static int choke_init(struct Qdisc *sch, struct nlattr *opt)
{
return choke_change(sch, opt);
}
--
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