netdev - Re: iproute2: tc deletion freezes whole server

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Message-ID: <CANxWus9v0Xn+RgyELT_fEOXiTUaf=z_GGCC695+Dy2LpXBcERg@mail.gmail.com>
Date:   Sun, 24 May 2020 12:03:54 +0200
From:   Václav Zindulka <vaclav.zindulka@...pnet.cz>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>
Subject: Re: iproute2: tc deletion freezes whole server

On Tue, May 19, 2020 at 7:57 PM Cong Wang <xiyou.wangcong@...il.com> wrote:
>
> On Tue, May 19, 2020 at 1:04 AM Václav Zindulka
> <vaclav.zindulka@...pnet.cz> wrote:
> > >
> > > Let me think how to fix this properly, I have some ideas and will provide
> > > you some patch(es) to test soon.
> >
> > Sure, I'll wait. I have plenty of time now with the main problem fixed :-)
>
> Can you help to test the patches below?
> https://github.com/congwang/linux/commits/qdisc_reset2
>
> I removed the last patch you previously tested and added two
> more patches on top. These two patches should get rid of most
> of the unnecessary resets. I tested them with veth pair with 8 TX
> queues, but I don't have any real physical NIC to test.
>
> Thanks.

I've tested it and I have to admit that your Kung-fu is even better
than mine :-D My large ruleset with over 13k qdiscs defined got from
22s to 520ms. I've tested downtime of interface during deletion of
root qdisc and it corresponds to the time I measured so it is great.

/usr/bin/time -p tc qdisc del dev enp1s0f0np0 root
real 0.52
user 0.00
sys 0.52

I've even added my patch for only active queues but it didn't make any
difference from your awesome patch :-)

Thank you very much. You helped me really a lot.