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authorEric Dumazet <eric.dumazet@gmail.com>2012-01-06 06:31:44 +0000
committerDavid S. Miller <davem@davemloft.net>2012-01-12 20:05:28 -0800
commitddecf0f4db44ef94847a62d6ecf74456b4dcc66f (patch)
tree48c49b70f83d713c7e3f594e067ee726bb70777e /include/net
parent72092cc45378176ba700034c91b7af2db524df26 (diff)
downloadop-kernel-dev-ddecf0f4db44ef94847a62d6ecf74456b4dcc66f.zip
op-kernel-dev-ddecf0f4db44ef94847a62d6ecf74456b4dcc66f.tar.gz
net_sched: sfq: add optional RED on top of SFQ
Adds an optional Random Early Detection on each SFQ flow queue. Traditional SFQ limits count of packets, while RED permits to also control number of bytes per flow, and adds ECN capability as well. 1) We dont handle the idle time management in this RED implementation, since each 'new flow' begins with a null qavg. We really want to address backlogged flows. 2) if headdrop is selected, we try to ecn mark first packet instead of currently enqueued packet. This gives faster feedback for tcp flows compared to traditional RED [ marking the last packet in queue ] Example of use : tc qdisc add dev $DEV parent 1:1 handle 10: est 1sec 4sec sfq \ limit 3000 headdrop flows 512 divisor 16384 \ redflowlimit 100000 min 8000 max 60000 probability 0.20 ecn qdisc sfq 10: parent 1:1 limit 3000p quantum 1514b depth 127 headdrop flows 512/16384 divisor 16384 ewma 6 min 8000b max 60000b probability 0.2 ecn prob_mark 0 prob_mark_head 4876 prob_drop 6131 forced_mark 0 forced_mark_head 0 forced_drop 0 Sent 1175211782 bytes 777537 pkt (dropped 6131, overlimits 11007 requeues 0) rate 99483Kbit 8219pps backlog 689392b 456p requeues 0 In this test, with 64 netperf TCP_STREAM sessions, 50% using ECN enabled flows, we can see number of packets CE marked is smaller than number of drops (for non ECN flows) If same test is run, without RED, we can check backlog is much bigger. qdisc sfq 10: parent 1:1 limit 3000p quantum 1514b depth 127 headdrop flows 512/16384 divisor 16384 Sent 1148683617 bytes 795006 pkt (dropped 0, overlimits 0 requeues 0) rate 98429Kbit 8521pps backlog 1221290b 841p requeues 0 Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Stephen Hemminger <shemminger@vyatta.com> CC: Dave Taht <dave.taht@gmail.com> Tested-by: Dave Taht <dave.taht@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/red.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/net/red.h b/include/net/red.h
index baab385..28068ec 100644
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -199,7 +199,8 @@ static inline void red_set_parms(struct red_parms *p,
p->Scell_log = Scell_log;
p->Scell_max = (255 << Scell_log);
- memcpy(p->Stab, stab, sizeof(p->Stab));
+ if (stab)
+ memcpy(p->Stab, stab, sizeof(p->Stab));
}
static inline int red_is_idling(const struct red_vars *v)
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