netdev - Re: net_sched 07/07: add classful multiqueue dummy scheduler

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Message-ID: <4AA7D1B3.7010708@trash.net>
Date:	Wed, 09 Sep 2009 18:02:59 +0200
From:	Patrick McHardy <kaber@...sh.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Jarek Poplawski <jarkao2@...il.com>, netdev@...r.kernel.org
Subject: Re: net_sched 07/07: add classful multiqueue dummy scheduler

Eric Dumazet wrote:
> Jarek Poplawski a écrit :
>> On Mon, Sep 07, 2009 at 03:27:37PM +0200, Patrick McHardy wrote:
>>> Jarek Poplawski wrote:
>> ...
>>>>> +static int mq_dump(struct Qdisc *sch, struct sk_buff *skb)
>>>>> +{
>>>>> +	struct net_device *dev = qdisc_dev(sch);
>>>>> +	struct Qdisc *qdisc;
>>>>> +	unsigned int ntx;
>>>>> +
>>>>> +	sch->q.qlen = 0;
>>>>> +	memset(&sch->bstats, 0, sizeof(sch->bstats));
>>>>> +	memset(&sch->qstats, 0, sizeof(sch->qstats));
>>>>> +
>>>>> +	for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
>>>>> +		qdisc = netdev_get_tx_queue(dev, ntx)->qdisc_sleeping;
>>>>> +		spin_lock_bh(qdisc_lock(qdisc));
>>>>> +		sch->q.qlen		+= qdisc->q.qlen;
>>>>> +		sch->bstats.bytes	+= qdisc->bstats.bytes;
>>>>> +		sch->bstats.packets	+= qdisc->bstats.packets;
>>>>> +		sch->qstats.qlen	+= qdisc->qstats.qlen;
>>>> Like in Christoph's case, we should probably use q.qlen instead.
>>> Its done a few lines above. This simply sums up all members of qstats.
>> AFAICS these members are updated only in tc_fill_qdisc, starting from
>> the root, so they might be not up-to-date at the moment, unless I miss
>> something.
>
> Yes, we might need an q->ops->update_stats(struct Qdisc *sch) method, and
> to recursively call it from mq_update_stats()

Unless I'm missing something, that shouldn't be necessary since
sch->q.qlen contains the correct sum of all child qdiscs and
this is used by tc_fill_qdisc to update qstats.qlen.
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