htb: refactor struct htb_sched fields for performance

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htb_sched structures are big, and source of false sharing on SMP.

Every time a packet is queued or dequeue, many cache lines must be
touched because structures are not lay out properly.

By carefully splitting htb_sched in two parts, and define sub structures
to increase data locality, we can improve performance dramatically on
SMP.

New htb_prio structure can also be used in htb_class to increase data
locality.

I got 26 % performance increase on a 24 threads machine, with 200
concurrent netperf in TCP_RR mode, using a HTB hierarchy of 4 classes.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Eric Dumazet 2013-06-15 03:30:10 -07:00 • committed by David S. Miller

parent bcefe17cff

commit c9364636dc

1 changed files with 95 additions and 86 deletions

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189

net/sched/sch_htb.c

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