linux-kernel - [PATCH net-next v2 0/3] Some optimization for lockless qdisc

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Message-ID: <1622684880-39895-1-git-send-email-linyunsheng@huawei.com>
Date:   Thu, 3 Jun 2021 09:47:57 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>
CC:     <olteanv@...il.com>, <ast@...nel.org>, <daniel@...earbox.net>,
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        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...neuler.org>, <mkl@...gutronix.de>,
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Subject: [PATCH net-next v2 0/3] Some optimization for lockless qdisc

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.

V2: Adjust the comment and commit log according to discussion
    in V1.
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            | 27 +++++++++++++++++++++++++--
 net/sched/sch_generic.c   | 23 ++++++++++++++++-------
 3 files changed, 59 insertions(+), 22 deletions(-)

-- 
2.7.4