From patchwork Wed May 16 20:29:06 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Patchwork-Id: 914919 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=toke.dk Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; secure) header.d=toke.dk header.i=@toke.dk header.b="d8Wunq3F"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 40mQz14ZpQz9s1B for ; Thu, 17 May 2018 06:29:49 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752096AbeEPU3m (ORCPT ); Wed, 16 May 2018 16:29:42 -0400 Received: from mail.toke.dk ([52.28.52.200]:57665 "EHLO mail.toke.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751893AbeEPU3P (ORCPT ); Wed, 16 May 2018 16:29:15 -0400 Subject: [PATCH net-next v12 7/7] sch_cake: Conditionally split GSO segments DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1526502547; bh=0r4vyga14Yj/GmWyAGPNOU7BCJ7tGWrbftCrbqGskbY=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=d8Wunq3FGVBphak1N5fQ2mIuw12xc8PURr9dSk+mGD1sPUTqKarVLOcycJLr8WL27 WLgHq/KHKa37D+8Q9kr37IPawtYtGdcnS7ZKIEzHQhSCNzc1E/UvBkx1L+OgjTgvpE PSxe+ajCLr+iM/q7QdBgWfKNQupbYdgT5nW0/E2kYUgrex0eogi284dYPvDNI5QI55 Z4qWoo3gx/Zq5Ja0kIX4gvjfopHfTSZa25PeYYC2WOiEAPus1mGudl+HBhiEW7pOF4 LGkW2JeYVvX0km7J62xH3fHdCmUw7+SMR/shGTbpoes5cbPpiSw4DS5l/Er135vfs4 lmx+WdnJD/GIg== From: Toke =?utf-8?q?H=C3=B8iland-J=C3=B8rgensen?= To: netdev@vger.kernel.org Cc: cake@lists.bufferbloat.net Date: Wed, 16 May 2018 22:29:06 +0200 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <152650254633.25701.8566251044868849195.stgit@alrua-kau> In-Reply-To: <152650253056.25701.10138252969621361651.stgit@alrua-kau> References: <152650253056.25701.10138252969621361651.stgit@alrua-kau> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 1ce81d919f73..dca276806e9f 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 */ /* struct cobalt_params - contains codel and blue parameters * @interval: codel initial drop rate @@ -1474,36 +1475,73 @@ 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]); @@ -2327,6 +2365,11 @@ 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); @@ -2482,6 +2525,10 @@ 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: