Commit a00bd469 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

sch_sfb: use skb_flow_dissect() 



Current SFB double hashing is not fulfilling SFB theory, if two flows
share same rxhash value.

Using skb_flow_dissect() permits to really have better hash dispersion,
and get tunnelling support as well.

Double hashing point was mentioned by Florian Westphal

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6bd2a9af

net/sched/sch_sfb.c

+14 −3
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <net/ip.h>

#include <net/pkt_sched.h>

#include <net/inet_ecn.h>

#include <net/flow_keys.h>



/*

 * SFB uses two B[l][n] : L x N arrays of bins (L levels, N bins per level)
@@ -286,6 +287,7 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch) 
	u32 minqlen = ~0;

	u32 r, slot, salt, sfbhash;

	int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;

	struct flow_keys keys;



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

		sch->qstats.overlimits++;
@@ -309,13 +311,19 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch) 
		/* If using external classifiers, get result and record it. */

		if (!sfb_classify(skb, q, &ret, &salt))

			goto other_drop;

		keys.src = salt;

		keys.dst = 0;

		keys.ports = 0;

	} else {

		salt = skb_get_rxhash(skb);

		skb_flow_dissect(skb, &keys);

	}



	slot = q->slot;



	sfbhash = jhash_1word(salt, q->bins[slot].perturbation);

	sfbhash = jhash_3words((__force u32)keys.dst,

			       (__force u32)keys.src,

			       (__force u32)keys.ports,

			       q->bins[slot].perturbation);

	if (!sfbhash)

		sfbhash = 1;

	sfb_skb_cb(skb)->hashes[slot] = sfbhash;
@@ -347,7 +355,10 @@ static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch) 
	if (unlikely(p_min >= SFB_MAX_PROB)) {

		/* Inelastic flow */

		if (q->double_buffering) {

			sfbhash = jhash_1word(salt, q->bins[slot].perturbation);

			sfbhash = jhash_3words((__force u32)keys.dst,

					       (__force u32)keys.src,

					       (__force u32)keys.ports,

					       q->bins[slot].perturbation);

			if (!sfbhash)

				sfbhash = 1;

			sfb_skb_cb(skb)->hashes[slot] = sfbhash;