[PATCH net-next 0/3] Some optimization for lockless qdisc

Yunsheng Lin
2021-05-28T02:50:12Z

Patch 1: remove unnecessary seqcount operation.
Patch 2: implement TCQ_F_CAN_BYPASS.
Patch 3: remove qdisc->empty.

Performance data for pktgen in queue_xmit mode + dummy netdev
with pfifo_fast:

threads unpatched patched delta
1 2.60Mpps 3.21Mpps +23%
2 3.84Mpps 5.56Mpps +44%
4 5.52Mpps 5.58Mpps +1%
8 2.77Mpps 2.76Mpps -0.3%
16 2.24Mpps 2.23Mpps +0.4%

Performance for IP forward testing: 1.05Mpps increases to
1.16Mpps, about 10% improvement.

V1: Drop RFC tag, Add nolock_qdisc_is_empty() and do the qdisc
empty checking without the protection of qdisc->seqlock to
aviod doing unnecessary spin_trylock() for contention case.
RFC v4: Use STATE_MISSED and STATE_DRAINING to indicate non-empty
qdisc, and add patch 1 and 3.

Yunsheng Lin (3):
net: sched: avoid unnecessary seqcount operation for lockless qdisc
net: sched: implement TCQ_F_CAN_BYPASS for lockless qdisc
net: sched: remove qdisc->empty for lockless qdisc

include/net/sch_generic.h | 31 ++++++++++++++++++-------------
net/core/dev.c | 26 ++++++++++++++++++++++++--
net/sched/sch_generic.c | 23 ++++++++++++++++-------
3 files changed, 58 insertions(+), 22 deletions(-)

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2.7.4