From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <eric.dumazet@gmail.com>
Received: from mail-wg0-f41.google.com (mail-wg0-f41.google.com [74.125.82.41])
	(using TLSv1 with cipher RC4-MD5 (128/128 bits))
	(Client CN "smtp.gmail.com",
	Issuer "Google Internet Authority" (verified OK))
	by huchra.bufferbloat.net (Postfix) with ESMTPS id 6C6062012AC
	for <codel@lists.bufferbloat.net>; Sat,  5 May 2012 13:20:56 -0700 (PDT)
Received: by wgbds1 with SMTP id ds1so2144983wgb.4
	for <codel@lists.bufferbloat.net>; Sat, 05 May 2012 13:20:54 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113;
	h=subject:from:to:cc:in-reply-to:references:content-type:date
	:message-id:mime-version:x-mailer:content-transfer-encoding;
	bh=ykPS+cOjE7ikDvtfLyOcjcvHiN/gFoEtAKAbqVxwsa4=;
	b=IADZTWq2HOdkxP4i75MEbXiTm2GwAQVfLBTT3yyMaaLP8Pt6US34h2eajEdB1edYPo
	4UHLikfjtJcIRCXSkvi4W5MRNoaTG5qhw+Iyo9DntqGkrIlxAhW50YJYH9pNKN3roNI4
	8L3M8357Ofuzod/Ia36awCOHn6o4bpScrixBVRzVc98Yzi1ie6gjHJ3nGWm9PHHpLneM
	iouiTwBiDqRkmtou2EfhIIVBYv2u07AO2bYxzGaL68QwAV11/KRmWNn65t1kBgJzsfWI
	6Nm6CSQpumqA6fTT/FbZHQVwygsoof/ZU1KpP2YLQdyvLcbtPaCee7wK+FkUsyPyPzod
	qkyA==
Received: by 10.180.92.130 with SMTP id cm2mr23133978wib.4.1336249254446;
	Sat, 05 May 2012 13:20:54 -0700 (PDT)
Received: from [172.28.130.107] ([74.125.122.49])
	by mx.google.com with ESMTPS id u9sm8470640wix.0.2012.05.05.13.20.52
	(version=SSLv3 cipher=OTHER); Sat, 05 May 2012 13:20:53 -0700 (PDT)
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Dave Taht <dave.taht@gmail.com>
In-Reply-To: <1336229343.3752.516.camel@edumazet-glaptop>
References: <1336217671-20384-1-git-send-email-dave.taht@bufferbloat.net>
	<CAA93jw4dXsn+ZCQH+LtZLqBqKXE+q3RUS97Avjy2dHHaCZ+_NA@mail.gmail.com>
	<1336218794.3752.508.camel@edumazet-glaptop>
	<1336229343.3752.516.camel@edumazet-glaptop>
Content-Type: text/plain; charset="UTF-8"
Date: Sat, 05 May 2012 22:20:51 +0200
Message-ID: <1336249251.3752.558.camel@edumazet-glaptop>
Mime-Version: 1.0
X-Mailer: Evolution 2.28.3 
Content-Transfer-Encoding: 7bit
Cc: codel@lists.bufferbloat.net,
	Dave =?ISO-8859-1?Q?T=E4ht?= <dave.taht@bufferbloat.net>
Subject: Re: [Codel] [PATCH v5] pkt_sched: codel: Controlled Delay AQM
X-BeenThere: codel@lists.bufferbloat.net
X-Mailman-Version: 2.1.13
Precedence: list
List-Id: CoDel AQM discussions <codel.lists.bufferbloat.net>
List-Unsubscribe: <https://lists.bufferbloat.net/options/codel>,
	<mailto:codel-request@lists.bufferbloat.net?subject=unsubscribe>
List-Archive: <https://lists.bufferbloat.net/private/codel>
List-Post: <mailto:codel@lists.bufferbloat.net>
List-Help: <mailto:codel-request@lists.bufferbloat.net?subject=help>
List-Subscribe: <https://lists.bufferbloat.net/listinfo/codel>,
	<mailto:codel-request@lists.bufferbloat.net?subject=subscribe>
X-List-Received-Date: Sat, 05 May 2012 20:20:57 -0000

On Sat, 2012-05-05 at 16:49 +0200, Eric Dumazet wrote:
> From: Dave Taht <dave.taht@gmail.com>
> 

> +static bool should_drop(struct sk_buff *skb, struct Qdisc *sch, ktime_t now)
> +{
> +	struct codel_sched_data *q = qdisc_priv(sch);
> +	ktime_t sojourn_time;
> +	bool drop;
> +
> +	if (!skb) {
> +		q->first_above_time.tv64 = 0;
> +		return false;
> +	}
> +	sojourn_time = ktime_sub(now, get_enqueue_time(skb));
> +
> +	if (ktime_compare(sojourn_time, q->target) < 0 || 
> +	    sch->qstats.backlog < q->minbytes) {
> +		/* went below so we'll stay below for at least q->interval */
> +		q->first_above_time.tv64 = 0;
> +		return false;
> +	}

I believe we should allow the last packet to be sent even if
sch->qstats.backlog >= q->minbytes

Hmm... this means we should do the 
sch->qstats.backlog -= qdisc_pkt_len(skb);
right after the calls to __skb_dequeue(&sch->q);

(and not in the codel_drop() or at end of codel_dequeue())