From patchwork Mon May 21 16:24:17 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: 917723 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="fqKnDemu"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 40qPHn4pWtz9s32 for ; Tue, 22 May 2018 02:24:37 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753252AbeEUQYf (ORCPT ); Mon, 21 May 2018 12:24:35 -0400 Received: from mail.toke.dk ([52.28.52.200]:51415 "EHLO mail.toke.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753231AbeEUQYX (ORCPT ); Mon, 21 May 2018 12:24:23 -0400 Subject: [PATCH net-next v13 7/7] sch_cake: Conditionally split GSO segments DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=toke.dk; s=20161023; t=1526919858; bh=KkB4YnsI4F8N2PXeyYYW24HlC25umYG1tCLKK8gE+qc=; h=Subject:From:To:Date:In-Reply-To:References:From; b=fqKnDemuU8DaRsDHAVxN2XL3pj63c3U2NHiGQ0KEMLaPhbjf3hUi4iNzN7o27tB2r WOX1+OVYLWeJwR5zj+5bd4sCCzZbRi3t6c/TuES6JrVIYd0K+zI7bnlk029OG84QoU gUnsUeyUMX6TcPjJsmc67Km4c454H5wChonRxHbAOf0n+F2i5nRIW76MBuZmJnEwC/ mKZbx5sld3Rv2kyaZQncDq7V821KWsmxiMomdZ1iRn94mx+crnbJDNiR6F52IHI202 YwHsKzyKCX5GN0/q9KqKna+U1MrAJTMhGvwZRhplBY8maLNw0tEDJ05AdpPeAZc8Uo O9zVnzj8d+C3w== From: Toke =?utf-8?q?H=C3=B8iland-J=C3=B8rgensen?= To: netdev@vger.kernel.org, cake@lists.bufferbloat.net Date: Mon, 21 May 2018 18:24:17 +0200 X-Clacks-Overhead: GNU Terry Pratchett Message-ID: <152691985754.4083.4638844457551283134.stgit@alrua-kau> In-Reply-To: <152691970035.4083.3349902669266371765.stgit@alrua-kau> References: <152691970035.4083.3349902669266371765.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 4bccfee714c8..1bf413759bd4 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 @@ -1643,36 +1644,73 @@ 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]); @@ -2504,6 +2542,11 @@ 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); @@ -2659,6 +2702,10 @@ 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: