Re: [LARTC] ESFQ?

[Andy Furniss <andy.furniss@dsl.pipex.com>]

Thomas Graf wrote:
> * Andy Furniss <41E3F088.6060708@dsl.pipex.com> 2005-01-11 15:28
> 
>>diff -urN linux-2.6.10.orig/include/linux/pkt_sched.h linux-2.6.10/include/linux/pkt_sched.h
>>@@ -136,6 +143,7 @@
>> 	__u32		limit;		/* Maximal packets in queue */
>> 	unsigned	divisor;	/* Hash divisor  */
>> 	unsigned	flows;		/* Maximal number of flows  */
>>+	unsigned	hash_kind;	/* Hash function to use for flow identification */
>> };
> 
> 
> This breaks compatibility to older iproute2 versions
> compiled with older header versions (not including
> the additional 4 octets). sch_sfq.c:
> 
>         if (opt->rta_len < RTA_LENGTH(sizeof(*ctl)))
> 	                return -EINVAL;

I did wonder if it could just come out now that iproute2 uses its own 
pkt_sched.h.

Just to be sure I understand  - it's a risk that always existed eg. 
before Stephen maintained iproute2, when it compiled against kernel 
headers. If I patched kernel and failed to compile new tc/had old tc 
ahead in path etc. then sfq would be broken.

So if you patch make sure you build and use new tc do tc -V / check you 
don't have an old one in /sbin as iproute2's make install uses /usr/sbin 
by default.


> 
>>+static int esfq_change(struct Qdisc *sch, struct rtattr *opt)
>>+{
>>+	struct esfq_sched_data *q = qdisc_priv(sch);
>>+	struct tc_sfq_qopt *ctl = RTA_DATA(opt);
>>+	int old_perturb = q->perturb_period;
>>+
>>+	if (opt->rta_len < RTA_LENGTH(sizeof(*ctl)))
>>+		return -EINVAL;
>>+
>>+	sch_tree_lock(sch);
>>+	q->quantum = ctl->quantum ? : psched_mtu(sch->dev);
>>+	q->perturb_period = ctl->perturb_period*HZ;
>>+//	q->hash_divisor = ctl->divisor;
>>+//	q->tail = q->limit = q->depth = ctl->flows;
>>+
>>+	if (ctl->limit)
>>+		q->limit = min_t(u32, ctl->limit, q->depth);
>>+	
>>+	if (ctl->hash_kind) {
>>+		q->hash_kind = ctl->hash_kind;
>>+		if (q->hash_kind !=  TCA_SFQ_HASH_CLASSIC)
>>+			q->perturb_period = 0;
>>+	}
>>+	
>>+	// is sch_tree_lock enough to do this ?
>>+	while (sch->q.qlen >= q->limit-1)
>>+		esfq_drop(sch);
>>+	
>>+	if (old_perturb)
>>+		del_timer(&q->perturb_timer);
>>+	if (q->perturb_period) {
>>+		q->perturb_timer.expires = jiffies + q->perturb_period;
>>+		add_timer(&q->perturb_timer);
>>+	} else {
>>+		q->perturbation = 0;
>>+	}
>>+	sch_tree_unlock(sch);
>>+	return 0;
>>+}
> 
> 
> Must be changed to use tcf_exts and ematch api once those patches
> are merged. I will take care of this.
> 
> I'll have a closer look later on this week.
> 

Thanks.

Andy.

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