From a3eb95f891d6130b1fc03dd07a8b54cf0a5c8ab8 Mon Sep 17 00:00:00 2001 From: David Ward Date: Sat, 9 May 2015 22:01:46 -0400 Subject: net_sched: gred: add TCA_GRED_LIMIT attribute In a GRED qdisc, if the default "virtual queue" (VQ) does not have drop parameters configured, then packets for the default VQ are not subjected to RED and are only dropped if the queue is larger than the net_device's tx_queue_len. This behavior is useful for WRED mode, since these packets will still influence the calculated average queue length and (therefore) the drop probability for all of the other VQs. However, for some drivers tx_queue_len is zero. In other cases the user may wish to make the limit the same for all VQs (including the default VQ with no drop parameters). This change adds a TCA_GRED_LIMIT attribute to set the GRED queue limit, in bytes, during qdisc setup. (This limit is in bytes to be consistent with the drop parameters.) The default limit is the same as for a bfifo queue (tx_queue_len * psched_mtu). If the drop parameters of any VQ are configured with a smaller limit than the GRED queue limit, that VQ will still observe the smaller limit instead. Signed-off-by: David Ward Signed-off-by: David S. Miller --- include/uapi/linux/pkt_sched.h | 3 ++- net/sched/sch_gred.c | 28 ++++++++++++++++++++++++---- 2 files changed, 26 insertions(+), 5 deletions(-) diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index 69d88b309cc7..8d2530daca9f 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -268,7 +268,8 @@ enum { TCA_GRED_STAB, TCA_GRED_DPS, TCA_GRED_MAX_P, - __TCA_GRED_MAX, + TCA_GRED_LIMIT, + __TCA_GRED_MAX, }; #define TCA_GRED_MAX (__TCA_GRED_MAX - 1) diff --git a/net/sched/sch_gred.c b/net/sched/sch_gred.c index a4ca4517cdc8..826e2994152b 100644 --- a/net/sched/sch_gred.c +++ b/net/sched/sch_gred.c @@ -165,7 +165,8 @@ static int gred_enqueue(struct sk_buff *skb, struct Qdisc *sch) * if no default DP has been configured. This * allows for DP flows to be left untouched. */ - if (skb_queue_len(&sch->q) < qdisc_dev(sch)->tx_queue_len) + if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= + sch->limit)) return qdisc_enqueue_tail(skb, sch); else goto drop; @@ -397,7 +398,10 @@ static inline int gred_change_vq(struct Qdisc *sch, int dp, q->DP = dp; q->prio = prio; - q->limit = ctl->limit; + if (ctl->limit > sch->limit) + q->limit = sch->limit; + else + q->limit = ctl->limit; if (q->backlog == 0) red_end_of_idle_period(&q->vars); @@ -414,6 +418,7 @@ static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = { [TCA_GRED_STAB] = { .len = 256 }, [TCA_GRED_DPS] = { .len = sizeof(struct tc_gred_sopt) }, [TCA_GRED_MAX_P] = { .type = NLA_U32 }, + [TCA_GRED_LIMIT] = { .type = NLA_U32 }, }; static int gred_change(struct Qdisc *sch, struct nlattr *opt) @@ -433,11 +438,15 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt) if (err < 0) return err; - if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) + if (tb[TCA_GRED_PARMS] == NULL && tb[TCA_GRED_STAB] == NULL) { + if (tb[TCA_GRED_LIMIT] != NULL) + sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]); return gred_change_table_def(sch, opt); + } if (tb[TCA_GRED_PARMS] == NULL || - tb[TCA_GRED_STAB] == NULL) + tb[TCA_GRED_STAB] == NULL || + tb[TCA_GRED_LIMIT] != NULL) return -EINVAL; max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0; @@ -501,6 +510,14 @@ static int gred_init(struct Qdisc *sch, struct nlattr *opt) if (tb[TCA_GRED_PARMS] || tb[TCA_GRED_STAB]) return -EINVAL; + if (tb[TCA_GRED_LIMIT]) + sch->limit = nla_get_u32(tb[TCA_GRED_LIMIT]); + else { + u32 qlen = qdisc_dev(sch)->tx_queue_len ? : 1; + + sch->limit = qlen * psched_mtu(qdisc_dev(sch)); + } + return gred_change_table_def(sch, tb[TCA_GRED_DPS]); } @@ -531,6 +548,9 @@ static int gred_dump(struct Qdisc *sch, struct sk_buff *skb) if (nla_put(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p)) goto nla_put_failure; + if (nla_put_u32(skb, TCA_GRED_LIMIT, sch->limit)) + goto nla_put_failure; + parms = nla_nest_start(skb, TCA_GRED_PARMS); if (parms == NULL) goto nla_put_failure; -- cgit v1.2.3