From 219e288e8900fac65211e0a23e2a1037fd521af1 Mon Sep 17 00:00:00 2001 From: Vijay Subramanian Date: Wed, 12 Feb 2014 18:58:21 -0800 Subject: net: sched: Cleanup PIE comments Fix incorrect comment reported by Norbert Kiesel. Edit another comment to add more details. Also add references to algorithm (IETF draft and paper) to top of file. Signed-off-by: Vijay Subramanian CC: Mythili Prabhu CC: Norbert Kiesel Signed-off-by: David S. Miller --- net/sched/sch_pie.c | 21 ++++++++++++++++----- 1 file changed, 16 insertions(+), 5 deletions(-) (limited to 'net/sched') diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c index a255d0200a59..fefeeb73f15f 100644 --- a/net/sched/sch_pie.c +++ b/net/sched/sch_pie.c @@ -15,6 +15,11 @@ * * ECN support is added by Naeem Khademi * University of Oslo, Norway. + * + * References: + * IETF draft submission: http://tools.ietf.org/html/draft-pan-aqm-pie-00 + * IEEE Conference on High Performance Switching and Routing 2013 : + * "PIE: A * Lightweight Control Scheme to Address the Bufferbloat Problem" */ #include @@ -36,7 +41,7 @@ struct pie_params { psched_time_t target; /* user specified target delay in pschedtime */ u32 tupdate; /* timer frequency (in jiffies) */ u32 limit; /* number of packets that can be enqueued */ - u32 alpha; /* alpha and beta are between -4 and 4 */ + u32 alpha; /* alpha and beta are between 0 and 32 */ u32 beta; /* and are used for shift relative to 1 */ bool ecn; /* true if ecn is enabled */ bool bytemode; /* to scale drop early prob based on pkt size */ @@ -326,10 +331,16 @@ static void calculate_probability(struct Qdisc *sch) if (qdelay == 0 && qlen != 0) update_prob = false; - /* Add ranges for alpha and beta, more aggressive for high dropping - * mode and gentle steps for light dropping mode - * In light dropping mode, take gentle steps; in medium dropping mode, - * take medium steps; in high dropping mode, take big steps. + /* In the algorithm, alpha and beta are between 0 and 2 with typical + * value for alpha as 0.125. In this implementation, we use values 0-32 + * passed from user space to represent this. Also, alpha and beta have + * unit of HZ and need to be scaled before they can used to update + * probability. alpha/beta are updated locally below by 1) scaling them + * appropriately 2) scaling down by 16 to come to 0-2 range. + * Please see paper for details. + * + * We scale alpha and beta differently depending on whether we are in + * light, medium or high dropping mode. */ if (q->vars.prob < MAX_PROB / 100) { alpha = -- cgit From 724b9e1d75ab3401aaa081bd4efb440c1b3509db Mon Sep 17 00:00:00 2001 From: Hiroaki SHIMODA Date: Wed, 26 Feb 2014 21:43:42 +0900 Subject: sch_tbf: Fix potential memory leak in tbf_change(). The allocated child qdisc is not freed in error conditions. Defer the allocation after user configuration turns out to be valid and acceptable. Fixes: cc106e441a63b ("net: sched: tbf: fix the calculation of max_size") Signed-off-by: Hiroaki SHIMODA Cc: Yang Yingliang Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/sched/sch_tbf.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) (limited to 'net/sched') diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c index 1cb413fead89..4f505a006896 100644 --- a/net/sched/sch_tbf.c +++ b/net/sched/sch_tbf.c @@ -334,18 +334,6 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt) qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate, tb[TCA_TBF_PTAB])); - if (q->qdisc != &noop_qdisc) { - err = fifo_set_limit(q->qdisc, qopt->limit); - if (err) - goto done; - } else if (qopt->limit > 0) { - child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit); - if (IS_ERR(child)) { - err = PTR_ERR(child); - goto done; - } - } - buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U); mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U); @@ -390,6 +378,18 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt) goto done; } + if (q->qdisc != &noop_qdisc) { + err = fifo_set_limit(q->qdisc, qopt->limit); + if (err) + goto done; + } else if (qopt->limit > 0) { + child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit); + if (IS_ERR(child)) { + err = PTR_ERR(child); + goto done; + } + } + sch_tree_lock(sch); if (child) { qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen); -- cgit