From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [52.28.52.200]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id F1EBE3CB35 for ; Tue, 15 May 2018 11:12:48 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1526397166; bh=uL1tJiZTBD+8JCqcWlThFWs2TwXR9vqjBKX769kI9JU=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=spHk2/lFdasRp2zxsAuqkF28RZwtkCDHI1LxiIztzrMLUKMdGOFnhrdhP5H0r8TBa NLBBbPRTS5dc9LQHqyLak8ftWj5t0d94vIMF/cKPGPYPU6/KjyWXWbofYjGNJI7NAX +Z9k39mehXSHNpzfKXcHtWufqGW7ZEirAjCKp8wxPxT0OETrJ8UJDvGwWxJu2nxL0K ffI2Dwighvwvpdw4xRcVI69GwOKYLIcbuvn6T/ddnr2SnPKQDAEeSPcEWpq2K27jX2 XYT0SxhZqQycc4n2oHUN8LqsCG5HlXB3yEqk4a/p1FMo6/xzxOCSqIUqBHcfB2MqYF Y/5pNqFJ2IWIQ== From: Toke =?utf-8?q?H=C3=B8iland-J=C3=B8rgensen?= To: netdev@vger.kernel.org Cc: cake@lists.bufferbloat.net Date: Tue, 15 May 2018 17:12:45 +0200 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <152639716522.2525.18141206757694286780.stgit@alrua-kau> In-Reply-To: <152639705919.2525.3718182212727523960.stgit@alrua-kau> References: <152639705919.2525.3718182212727523960.stgit@alrua-kau> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Subject: [Cake] [PATCH net-next v11 7/7] sch_cake: Conditionally split GSO segments X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 May 2018 15:12:49 -0000 At lower bandwidths, the transmission time of a single GSO segment can add an unacceptable amount of latency due to HOL blocking. Furthermore, with a software shaper, any tuning mechanism employed by the kernel to control the maximum size of GSO segments is thrown off by the artificial limit on bandwidth. For this reason, we split GSO segments into their individual packets iff the shaper is active and configured to a bandwidth <= 1 Gbps. Signed-off-by: Toke Høiland-Jørgensen --- net/sched/sch_cake.c | 99 +++++++++++++++++++++++++++++++++++++------------- 1 file changed, 73 insertions(+), 26 deletions(-) diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c index a4aad577bf8e..a0c2925b4c54 100644 --- a/net/sched/sch_cake.c +++ b/net/sched/sch_cake.c @@ -82,6 +82,7 @@ #define CAKE_QUEUES (1024) #define CAKE_FLOW_MASK 63 #define CAKE_FLOW_NAT_FLAG 64 +#define CAKE_SPLIT_GSO_THRESHOLD (125000000) /* 1Gbps */ #define US2TIME(a) (a * (u64)NSEC_PER_USEC) typedef u64 cobalt_time_t; @@ -1477,36 +1478,73 @@ static s32 cake_enqueue(struct sk_buff *skb, struct Qdisc *sch, if (unlikely(len > b->max_skblen)) b->max_skblen = len; - cobalt_set_enqueue_time(skb, now); - get_cobalt_cb(skb)->adjusted_len = cake_overhead(q, skb); - flow_queue_add(flow, skb); - - if (q->ack_filter) - ack = cake_ack_filter(q, flow); + if (skb_is_gso(skb) && q->rate_flags & CAKE_FLAG_SPLIT_GSO) { + struct sk_buff *segs, *nskb; + netdev_features_t features = netif_skb_features(skb); + unsigned int slen = 0; + + segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK); + if (IS_ERR_OR_NULL(segs)) + return qdisc_drop(skb, sch, to_free); + + while (segs) { + nskb = segs->next; + segs->next = NULL; + qdisc_skb_cb(segs)->pkt_len = segs->len; + cobalt_set_enqueue_time(segs, now); + get_cobalt_cb(segs)->adjusted_len = cake_overhead(q, + segs); + flow_queue_add(flow, segs); + + sch->q.qlen++; + slen += segs->len; + q->buffer_used += segs->truesize; + b->packets++; + segs = nskb; + } - if (ack) { - b->ack_drops++; - sch->qstats.drops++; - b->bytes += qdisc_pkt_len(ack); - len -= qdisc_pkt_len(ack); - q->buffer_used += skb->truesize - ack->truesize; - if (q->rate_flags & CAKE_FLAG_INGRESS) - cake_advance_shaper(q, b, ack, now, true); + /* stats */ + b->bytes += slen; + b->backlogs[idx] += slen; + b->tin_backlog += slen; + sch->qstats.backlog += slen; + q->avg_window_bytes += slen; - qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(ack)); - consume_skb(ack); + qdisc_tree_reduce_backlog(sch, 1, len); + consume_skb(skb); } else { - sch->q.qlen++; - q->buffer_used += skb->truesize; - } + /* not splitting */ + cobalt_set_enqueue_time(skb, now); + get_cobalt_cb(skb)->adjusted_len = cake_overhead(q, skb); + flow_queue_add(flow, skb); + + if (q->ack_filter) + ack = cake_ack_filter(q, flow); + + if (ack) { + b->ack_drops++; + sch->qstats.drops++; + b->bytes += qdisc_pkt_len(ack); + len -= qdisc_pkt_len(ack); + q->buffer_used += skb->truesize - ack->truesize; + if (q->rate_flags & CAKE_FLAG_INGRESS) + cake_advance_shaper(q, b, ack, now, true); + + qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(ack)); + consume_skb(ack); + } else { + sch->q.qlen++; + q->buffer_used += skb->truesize; + } - /* stats */ - b->packets++; - b->bytes += len; - b->backlogs[idx] += len; - b->tin_backlog += len; - sch->qstats.backlog += len; - q->avg_window_bytes += len; + /* stats */ + b->packets++; + b->bytes += len; + b->backlogs[idx] += len; + b->tin_backlog += len; + sch->qstats.backlog += len; + q->avg_window_bytes += len; + } if (q->overflow_timeout) cake_heapify_up(q, b->overflow_idx[idx]); @@ -2314,6 +2352,11 @@ static int cake_change(struct Qdisc *sch, struct nlattr *opt, if (tb[TCA_CAKE_MEMORY]) q->buffer_config_limit = nla_get_u32(tb[TCA_CAKE_MEMORY]); + if (q->rate_bps && q->rate_bps <= CAKE_SPLIT_GSO_THRESHOLD) + q->rate_flags |= CAKE_FLAG_SPLIT_GSO; + else + q->rate_flags &= ~CAKE_FLAG_SPLIT_GSO; + if (q->tins) { sch_tree_lock(sch); cake_reconfigure(sch); @@ -2469,6 +2512,10 @@ static int cake_dump(struct Qdisc *sch, struct sk_buff *skb) if (nla_put_u32(skb, TCA_CAKE_MPU, q->rate_mpu)) goto nla_put_failure; + if (nla_put_u32(skb, TCA_CAKE_SPLIT_GSO, + !!(q->rate_flags & CAKE_FLAG_SPLIT_GSO))) + goto nla_put_failure; + return nla_nest_end(skb, opts); nla_put_failure: