From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.toke.dk (mail.toke.dk [IPv6:2001:470:dc45:1000::1]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 310313F411 for ; Mon, 14 May 2018 15:00:33 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1526324430; bh=qzgx5q5MDO9gWkfWGZ/Fbo50fgnzI+/6czUXuPcgNnc=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=dcpPQ+A6Tm7GKHXhH8DkUCZe/G6ST7nsQkcu0yIapXKESPF/hRXUJoCpbOF/vjHIv XWfuxEwVw09XJnBhz+excH+3lPM/dTXPP3K1ZOQpdExrJ2Mae2apE+FohWmhpDA6ng K5mb9xGkbGYVpyRgurd+5M0AcpNX6cAe4sZttr5c7unLTpDAL8Vn8ddb7obocxPZZC N6sniV3lYDu/vL8WicjHZJsTCrFrELloX1EtDV8927wGIdaLqLHaTP6kI5guQObMMo u2S73pM63fT3zJPrt4ZhyE8nk4+rwfXYQoXGi2XIV9kCh55bFqHhUlbQKVL9lj65ZS 8msb+RI5asqxQ== From: Toke =?utf-8?q?H=C3=B8iland-J=C3=B8rgensen?= To: netdev@vger.kernel.org Cc: cake@lists.bufferbloat.net Date: Mon, 14 May 2018 21:00:30 +0200 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <152632443000.4861.2425632976298293927.stgit@alrua-kau> In-Reply-To: <152632431302.4861.16657365789045735410.stgit@alrua-kau> References: <152632431302.4861.16657365789045735410.stgit@alrua-kau> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Subject: [Cake] [PATCH net-next v10 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: Mon, 14 May 2018 19:00:33 -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 6314a089a204..0c2cf8bc0a03 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); @@ -2467,6 +2510,10 @@ 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: