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Commit eeaeb068 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

sch_sfq: allow big packets and be fair 



SFQ is currently 'limited' to small packets, because it uses a 15bit
allotment number per flow. Introduce a scale by 8, so that we can handle
full size TSO/GRO packets.

Use appropriate handling to make sure allot is positive before a new
packet is dequeued, so that fairness is respected.

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Acked-by: default avatarJarek Poplawski <jarkao2@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0f333d10

net/sched/sch_sfq.c

+19 −7
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ 


	IMPLEMENTATION:

	This implementation limits maximal queue length to 128;

	maximal mtu to 2^15-1; max 128 flows, number of hash buckets to 1024.

	max mtu to 2^18-1; max 128 flows, number of hash buckets to 1024.

	The only goal of this restrictions was that all data

	fit into one 4K page on 32bit arches.
@@ -77,6 +77,11 @@ 
#define SFQ_SLOTS		128 /* max number of flows */

#define SFQ_EMPTY_SLOT		255

#define SFQ_HASH_DIVISOR	1024

/* We use 16 bits to store allot, and want to handle packets up to 64K

 * Scale allot by 8 (1<<3) so that no overflow occurs.

 */

#define SFQ_ALLOT_SHIFT		3

#define SFQ_ALLOT_SIZE(X)	DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT)



/* This type should contain at least SFQ_DEPTH + SFQ_SLOTS values */

typedef unsigned char sfq_index;
@@ -115,7 +120,7 @@ struct sfq_sched_data 
	struct timer_list perturb_timer;

	u32		perturbation;

	sfq_index	cur_depth;	/* depth of longest slot */



	unsigned short  scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */

	struct sfq_slot *tail;		/* current slot in round */

	sfq_index	ht[SFQ_HASH_DIVISOR];	/* Hash table */

	struct sfq_slot	slots[SFQ_SLOTS];
@@ -395,7 +400,7 @@ sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) 
			q->tail->next = x;

		}

		q->tail = slot;

		slot->allot = q->quantum;

		slot->allot = q->scaled_quantum;

	}

	if (++sch->q.qlen <= q->limit) {

		sch->bstats.bytes += qdisc_pkt_len(skb);
@@ -431,8 +436,14 @@ sfq_dequeue(struct Qdisc *sch) 
	if (q->tail == NULL)

		return NULL;



next_slot:

	a = q->tail->next;

	slot = &q->slots[a];

	if (slot->allot <= 0) {

		q->tail = slot;

		slot->allot += q->scaled_quantum;

		goto next_slot;

	}

	skb = slot_dequeue_head(slot);

	sfq_dec(q, a);

	sch->q.qlen--;
@@ -447,9 +458,8 @@ sfq_dequeue(struct Qdisc *sch) 
			return skb;

		}

		q->tail->next = next_a;

	} else if ((slot->allot -= qdisc_pkt_len(skb)) <= 0) {

		q->tail = slot;

		slot->allot += q->quantum;

	} else {

		slot->allot -= SFQ_ALLOT_SIZE(qdisc_pkt_len(skb));

	}

	return skb;

}
@@ -485,6 +495,7 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt) 


	sch_tree_lock(sch);

	q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch));

	q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);

	q->perturb_period = ctl->perturb_period * HZ;

	if (ctl->limit)

		q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1);
@@ -525,6 +536,7 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt) 
	q->tail = NULL;

	if (opt == NULL) {

		q->quantum = psched_mtu(qdisc_dev(sch));

		q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum);

		q->perturb_period = 0;

		q->perturbation = net_random();

	} else {
@@ -617,7 +629,7 @@ static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl, 
	if (idx != SFQ_EMPTY_SLOT) {

		const struct sfq_slot *slot = &q->slots[idx];



		xstats.allot = slot->allot;

		xstats.allot = slot->allot << SFQ_ALLOT_SHIFT;

		qs.qlen = slot->qlen;

		slot_queue_walk(slot, skb)

			qs.backlog += qdisc_pkt_len(skb);