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Merge branch 'net-sched-singly-linked-list'
Florian Westphal says:
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sched: convert queues to single-linked list
During Netfilter Workshop 2016 Eric Dumazet pointed out that qdisc
schedulers use doubly-linked lists, even though single-linked list
would be enough.
The double-linked skb lists incur one extra write on enqueue/dequeue
operations (to change ->prev pointer of next list elem).
This series converts qdiscs to single-linked version, listhead
maintains pointers to first (for dequeue) and last skb (for enqueue).
Most qdiscs don't queue at all and instead use a leaf qdisc (typically
pfifo_fast) so only a few schedulers needed changes.
I briefly tested netem and htb and they seemed fine.
UDP_STREAM netperf with 64 byte packets via veth+pfifo_fast shows
a small (~2%) improvement.
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Signed-off-by: David S. Miller <davem@davemloft.net>