[Cake] cake_heap* could use some comments

[Cake] cake_heap* could use some comments

[Dave Taht]

1) Cake_heap* functions could use a set of explanatory comments.

In cake_heapify especially:

1a) m, mb, l are really not self explanatory. "major". "major byte". "lost"?
r is right? l is left? a is CAKE_MAX_HEAP.

2) What's the operating principle of the overflow_timeout?

3) Why the divide by 2 here:

static unsigned int cake_drop(struct Qdisc *sch, struct sk_buff **to_free)
{
struct cake_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
u32 idx = 0, tin = 0, len;
struct cake_tin_data *b;
struct cake_flow *flow;
struct cake_heap_entry qq;
u64 now = cobalt_get_time();

if (!q->overflow_timeout) {
int i;
/* Build fresh max-heap */
for (i = CAKE_MAX_TINS * CAKE_QUEUES / 2; i >= 0; i--)
cake_heapify(q, i);
//



-- 

Dave Täht
CEO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-669-226-2619

Re: [Cake] cake_heap* could use some comments

[Jonathan Morton]

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These are standard heap algorithms whose operation should be easily
recognisable.  The build loop runs over the set of non-leaf nodes,
implicitly accessing both children which are automatically at double the
index.

The timeout is simply there to elide the overhead of maintaining the heap
when hard dropping hasn't been necessary for a while.

- Jonathan Morton

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