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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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-11-28 05:25:02 +00:00 committed by David S. Miller
parent 6bd2a9af17
commit a00bd469b6
1 changed files with 14 additions and 3 deletions
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17
net/sched/sch_sfb.c
View File

@ -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;