Re: [PATCH v2] net_sched: sch_sfq: fix allot handling

From: Eric Dumazet <eric.dumazet@gmail.com>
To: Patrick McHardy <kaber@trash.net>
Cc: David Miller <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>,
	Jarek Poplawski <jarkao2@gmail.com>
Subject: Re: [PATCH v2] net_sched: sch_sfq: fix allot handling
Date: Wed, 15 Dec 2010 17:55:20 +0100	[thread overview]
Message-ID: <1292432120.3427.366.camel@edumazet-laptop> (raw)
In-Reply-To: <4D08F025.5030603@trash.net>

Le mercredi 15 décembre 2010 à 17:43 +0100, Patrick McHardy a écrit :

> Now we could remove the allot increase in sfq_dequeue for
> the case that the flow becomes inactive. It is incorrect
> anyways.

Hmm, we increase the allot for the next slot, not for the slot now
empty.

        /* Is the slot empty? */
        if (q->qs[a].qlen == 0) {
                q->ht[q->hash[a]] = SFQ_DEPTH;
                a = q->next[a]; // a = next slot index
                if (a == old_a) {
                        q->tail = SFQ_DEPTH;
                        return skb;
                }
                q->next[q->tail] = a;
                q->allot[a] += q->quantum;
// HERE, q->allot[a] is for next slot, we give it its quantum for being
activated

        } else if ((q->allot[a] -= qdisc_pkt_len(skb)) <= 0) {

Maybe we should rename (a / old_a) by (a / next_a) to avoid confusion :)

I was thinking in allowing more packets per SFQ (but keep the 126 active
flows limit), what do you think ?