netdev - Re: [next-queue PATCH v7 4/6] net/sched: Introduce Credit Based Shaper (CBS) qdisc

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Date:   Fri, 13 Oct 2017 15:54:19 -0700
From:   Vinicius Costa Gomes <vinicius.gomes@...el.com>
To:     Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
Cc:     netdev@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
        jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        andre.guedes@...el.com, ivan.briano@...el.com,
        jesus.sanchez-palencia@...el.com, boon.leong.ong@...el.com,
        richardcochran@...il.com, henrik@...tad.us, levipearson@...il.com,
        rodney.cummings@...com
Subject: Re: [next-queue PATCH v7 4/6] net/sched: Introduce Credit Based Shaper (CBS) qdisc

Hi,

Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org> writes:

[...]

>> +
>> +static int cbs_enqueue_soft(struct sk_buff *skb, struct Qdisc *sch)
>> +{
>> +	struct cbs_sched_data *q = qdisc_priv(sch);
>> +
>> +	if (sch->q.qlen == 0 && q->credits > 0) {
>> +		/* We need to stop accumulating credits when there's
>> +		 * no packet enqueued packets and q->credits is
> no packet -> no

Ugh. Fixed.

>
>> +		 * positive.
>> +		 */
>> +		q->credits = 0;
>> +		q->last = ktime_get_ns();
>> +	}
>> +
>> +	return qdisc_enqueue_tail(skb, sch);
>> +}
>> +

[...]

>> +static struct sk_buff *cbs_dequeue_soft(struct Qdisc *sch)
>> +{
>> +	struct cbs_sched_data *q = qdisc_priv(sch);
>> +	s64 now = ktime_get_ns();
>> +	struct sk_buff *skb;
>> +	s64 credits;
>> +	int len;
>> +
>> +	if (q->credits < 0) {
>> +		credits = timediff_to_credits(now - q->last, q->idleslope);
> Maybe be better to add small optimization by moving some calculations from data
> path, I mean, save idle_slope in bytes instead of kbit and converting it for
> every packet. Both delay_from_credits() and timediff_to_credits() is used only
> once and with idle_slope only...and both of them converting it.
>
> Same for credits_from_len() and send slope, save it in units of port_rate.
>

Done. Thanks.


Cheers,
--
Vinicius