netdev - Re: [net v4 2/3] net: sched: add check tc_skip

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Date:   Tue, 7 Dec 2021 10:16:44 +0800
From:   Tonghao Zhang <xiangxia.m.yue@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>,
        Antoine Tenart <atenart@...nel.org>,
        Alexander Lobakin <alexandr.lobakin@...el.com>,
        Wei Wang <weiwan@...gle.com>, Arnd Bergmann <arnd@...db.de>
Subject: Re: [net v4 2/3] net: sched: add check tc_skip_classify in sch egress

On Sat, Dec 4, 2021 at 9:42 AM Tonghao Zhang <xiangxia.m.yue@...il.com> wrote:
>
> On Sat, Dec 4, 2021 at 5:35 AM Daniel Borkmann <daniel@...earbox.net> wrote:
> >
> > On 12/2/21 3:47 AM, xiangxia.m.yue@...il.com wrote:
> > > From: Tonghao Zhang <xiangxia.m.yue@...il.com>
> > >
> > > Try to resolve the issues as below:
> > > * We look up and then check tc_skip_classify flag in net
> > >    sched layer, even though skb don't want to be classified.
> > >    That case may consume a lot of cpu cycles.
> > >
> > >    Install the rules as below:
> > >    $ for id in $(seq 1 10000); do
> > >    $       tc filter add ... egress prio $id ... action mirred egress redirect dev ifb0
> > >    $ done
> > >
> > >    netperf:
> > >    $ taskset -c 1 netperf -t TCP_RR -H ip -- -r 32,32
> > >    $ taskset -c 1 netperf -t TCP_STREAM -H ip -- -m 32
> > >
> > >    Before: 152.04 tps, 0.58 Mbit/s
> > >    After:  303.07 tps, 1.51 Mbit/s
> > >    For TCP_RR, there are 99.3% improvement, TCP_STREAM 160.3%.
> >
> > As it was pointed out earlier by Eric in v3, these numbers are moot since noone
> > is realistically running such a setup in practice with 10k linear rules.
> Yes. As I said in v1, in production, we use the 5+ prio. With this
> patch, little improvements, 1.x%
>
> This patch also fixes the packets loopback, if we use the bpf_redirect
> to ifb in egress path.
Hi Daniel, Eric
What should I do next？This patch try to fix the bug, and improve the
performance(~1% in production).
Should I update the commit message and send v5?
> --
> Best regards, Tonghao



-- 
Best regards, Tonghao