From dfcb63ce1de6b10ba98dee928f9463f37e5a5512 Mon Sep 17 00:00:00 2001 From: Toke Høiland-Jørgensen Date: Tue, 19 Oct 2021 19:47:09 +0200 Subject: fq_codel: generalise ce_threshold marking for subset of traffic MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit e72aeb9ee0e3 ("fq_codel: implement L4S style ce_threshold_ect1 marking") expanded the ce_threshold feature of FQ-CoDel so it can be applied to a subset of the traffic, using the ECT(1) bit of the ECN field as the classifier. However, hard-coding ECT(1) as the only classifier for this feature seems limiting, so let's expand it to be more general. To this end, change the parameter from a ce_threshold_ect1 boolean, to a one-byte selector/mask pair (ce_threshold_{selector,mask}) which is applied to the whole diffserv/ECN field in the IP header. This makes it possible to classify packets by any value in either the ECN field or the diffserv field. In particular, setting a selector of INET_ECN_ECT_1 and a mask of INET_ECN_MASK corresponds to the functionality before this patch, and a mask of ~INET_ECN_MASK allows using the selector as a straight-forward match against a diffserv code point: # apply ce_threshold to ECT(1) traffic tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x1/0x3 # apply ce_threshold to ECN-capable traffic marked as diffserv AF22 tc qdisc replace dev eth0 root fq_codel ce_threshold 1ms ce_threshold_selector 0x50/0xfc Regardless of the selector chosen, the normal rules for ECN-marking of packets still apply, i.e., the flow must still declare itself ECN-capable by setting one of the bits in the ECN field to get marked at all. v2: - Add tc usage examples to patch description Signed-off-by: Toke Høiland-Jørgensen Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20211019174709.69081-1-toke@redhat.com Signed-off-by: Jakub Kicinski --- include/net/codel.h | 7 +++++-- include/net/codel_impl.h | 14 +++++++------- include/uapi/linux/pkt_sched.h | 3 ++- 3 files changed, 14 insertions(+), 10 deletions(-) (limited to 'include') diff --git a/include/net/codel.h b/include/net/codel.h index 5e8b181b76b8..a6c9e34e62b8 100644 --- a/include/net/codel.h +++ b/include/net/codel.h @@ -102,7 +102,9 @@ static inline u32 codel_time_to_us(codel_time_t val) * @interval: width of moving time window * @mtu: device mtu, or minimal queue backlog in bytes. * @ecn: is Explicit Congestion Notification enabled - * @ce_threshold_ect1: if ce_threshold only marks ECT(1) packets + * @ce_threshold_selector: apply ce_threshold to packets matching this value + * in the diffserv/ECN byte of the IP header + * @ce_threshold_mask: mask to apply to ce_threshold_selector comparison */ struct codel_params { codel_time_t target; @@ -110,7 +112,8 @@ struct codel_params { codel_time_t interval; u32 mtu; bool ecn; - bool ce_threshold_ect1; + u8 ce_threshold_selector; + u8 ce_threshold_mask; }; /** diff --git a/include/net/codel_impl.h b/include/net/codel_impl.h index 7af2c3eb3c43..137d40d8cbeb 100644 --- a/include/net/codel_impl.h +++ b/include/net/codel_impl.h @@ -54,7 +54,8 @@ static void codel_params_init(struct codel_params *params) params->interval = MS2TIME(100); params->target = MS2TIME(5); params->ce_threshold = CODEL_DISABLED_THRESHOLD; - params->ce_threshold_ect1 = false; + params->ce_threshold_mask = 0; + params->ce_threshold_selector = 0; params->ecn = false; } @@ -250,13 +251,12 @@ end: if (skb && codel_time_after(vars->ldelay, params->ce_threshold)) { bool set_ce = true; - if (params->ce_threshold_ect1) { - /* Note: if skb_get_dsfield() returns -1, following - * gives INET_ECN_MASK, which is != INET_ECN_ECT_1. - */ - u8 ecn = skb_get_dsfield(skb) & INET_ECN_MASK; + if (params->ce_threshold_mask) { + int dsfield = skb_get_dsfield(skb); - set_ce = (ecn == INET_ECN_ECT_1); + set_ce = (dsfield >= 0 && + (((u8)dsfield & params->ce_threshold_mask) == + params->ce_threshold_selector)); } if (set_ce && INET_ECN_set_ce(skb)) stats->ce_mark++; diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index 6be9a84cccfa..f292b467b27f 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -840,7 +840,8 @@ enum { TCA_FQ_CODEL_CE_THRESHOLD, TCA_FQ_CODEL_DROP_BATCH_SIZE, TCA_FQ_CODEL_MEMORY_LIMIT, - TCA_FQ_CODEL_CE_THRESHOLD_ECT1, + TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR, + TCA_FQ_CODEL_CE_THRESHOLD_MASK, __TCA_FQ_CODEL_MAX }; -- cgit v1.2.3-58-ga151