Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <1616050402-37023-1-git-send-email-linyunsheng@huawei.com> <e5c2d82c-0158-3997-80b6-4aab56c61367@huawei.com>
In-Reply-To: <e5c2d82c-0158-3997-80b6-4aab56c61367@huawei.com>
From:   Cong Wang <xiyou.wangcong@gmail.com>
Date:   Fri, 19 Mar 2021 12:45:30 -0700
Message-ID: <CAM_iQpV4HX5L1b8ofUig-bi3r_MDdsjThqaxfoRCd=02XZBprQ@mail.gmail.com>
Subject: Re: [Linuxarm] [PATCH net] net: sched: fix packet stuck problem for
 lockless qdisc
To:     Yunsheng Lin <linyunsheng@huawei.com>
Cc:     David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Vladimir Oltean <olteanv@gmail.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andriin@fb.com>,
        Eric Dumazet <edumazet@google.com>,
        Wei Wang <weiwan@google.com>,
        "Cong Wang ." <cong.wang@bytedance.com>,
        Taehee Yoo <ap420073@gmail.com>,
        Linux Kernel Network Developers <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>, linuxarm@openeuler.org,
        Marc Kleine-Budde <mkl@pengutronix.de>,
        linux-can@vger.kernel.org, Jamal Hadi Salim <jhs@mojatatu.com>,
        Jiri Pirko <jiri@resnulli.us>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>, kpsingh@kernel.org,
        bpf <bpf@vger.kernel.org>, Jonas Bonn <jonas.bonn@netrounds.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Michael Zhivich <mzhivich@akamai.com>,
        Josh Hunt <johunt@akamai.com>, Jike Song <albcamus@gmail.com>,
        Kehuan Feng <kehuan.feng@gmail.com>,
        Ahmad Fatoum <a.fatoum@pengutronix.de>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, Mar 19, 2021 at 2:25 AM Yunsheng Lin <linyunsheng@huawei.com> wrote:
> I had done some performance test to see if there is value to
> fix the packet stuck problem and support lockless qdisc bypass,
> here is some result using pktgen in 'queue_xmit' mode on a dummy
> device as Paolo Abeni had done in [1], and using pfifo_fast qdisc:
>
> threads  vanilla    locked-qdisc    vanilla+this_patch
>    1     2.6Mpps      2.9Mpps            2.5Mpps
>    2     3.9Mpps      4.8Mpps            3.6Mpps
>    4     5.6Mpps      3.0Mpps            4.7Mpps
>    8     2.7Mpps      1.6Mpps            2.8Mpps
>    16    2.2Mpps      1.3Mpps            2.3Mpps
>
> locked-qdisc: test by removing the "TCQ_F_NOLOCK | TCQ_F_CPUSTATS".

I read this as this patch introduces somehow a performance
regression for -net, as the lockless bypass patch you submitted is
for -net-next.

Thanks.