From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH 3/5] netem: optimize tfifo Date: Wed, 21 Mar 2007 10:42:34 -0700 Message-ID: <20070321174422.654525319@linux-foundation.org> References: <20070321174231.890361963@linux-foundation.org> Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from smtp.osdl.org ([65.172.181.24]:46928 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933294AbXCUR7C (ORCPT ); Wed, 21 Mar 2007 13:59:02 -0400 Content-Disposition: inline; filename=netem-tfifo-opt.patch Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org In most cases, the next packet will be sent after the last one. So optimize that case. Signed-off-by: Stephen Hemminger --- net/sched/sch_netem.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) --- net-2.6.22.orig/net/sched/sch_netem.c +++ net-2.6.22/net/sched/sch_netem.c @@ -478,22 +478,28 @@ static int netem_change(struct Qdisc *sc */ struct fifo_sched_data { u32 limit; + psched_time_t oldest; }; static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch) { struct fifo_sched_data *q = qdisc_priv(sch); struct sk_buff_head *list = &sch->q; - const struct netem_skb_cb *ncb - = (const struct netem_skb_cb *)nskb->cb; + psched_time_t tnext = ((struct netem_skb_cb *)nskb->cb)->time_to_send; struct sk_buff *skb; if (likely(skb_queue_len(list) < q->limit)) { + /* Optimize for add at tail */ + if (likely(skb_queue_empty(list) || !PSCHED_TLESS(tnext, q->oldest))) { + q->oldest = tnext; + return qdisc_enqueue_tail(nskb, sch); + } + skb_queue_reverse_walk(list, skb) { const struct netem_skb_cb *cb = (const struct netem_skb_cb *)skb->cb; - if (!PSCHED_TLESS(ncb->time_to_send, cb->time_to_send)) + if (!PSCHED_TLESS(tnext, cb->time_to_send)) break; } @@ -506,7 +512,7 @@ static int tfifo_enqueue(struct sk_buff return NET_XMIT_SUCCESS; } - return qdisc_drop(nskb, sch); + return qdisc_reshape_fail(nskb, sch); } static int tfifo_init(struct Qdisc *sch, struct rtattr *opt) @@ -522,6 +528,7 @@ static int tfifo_init(struct Qdisc *sch, } else q->limit = max_t(u32, sch->dev->tx_queue_len, 1); + PSCHED_SET_PASTPERFECT(q->oldest); return 0; } --