netdev - Re: BBR and TCP internal pacing causing interrupt storm with pfifo

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Message-ID: <CANn89iLOHxOOuGzqNODk0hNWJ7an0bZXs4G-8mQjq3WWhZPo9g@mail.gmail.com>
Date:   Tue, 9 Oct 2018 10:26:10 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     zelo.zejn@...il.com
Cc:     Eric Dumazet <eric.dumazet@...il.com>, Kevin Yang <yyd@...gle.com>,
        netdev <netdev@...r.kernel.org>
Subject: Re: BBR and TCP internal pacing causing interrupt storm with pfifo_fast

On Tue, Oct 9, 2018 at 10:22 AM Gasper Zejn <zelo.zejn@...il.com> wrote:
>
> On 09. 10. 2018 19:00, Eric Dumazet wrote:
> >
> > On 10/09/2018 09:38 AM, Gasper Zejn wrote:
> >> Hello,
> >>
> >> I am seeing interrupt storms of over 100k-900k local timer interrupts
> >> when changing between network devices or networks with open TCP
> >> connections when not using sch_fq (I was using pfifo_fast). Using sch_fq
> >> makes the bug with interrupt storm go away.
> >>
> > That is for what kind of traffic ?
> >
> > If your TCP flows send 100k-3M packets per second, then yes, the pacing timers
> > could be setup in the 100k-900k range.
> >
> Traffic is nowhere in that range, think of having a few browser tabs of
> javascript rich
> web pages open, mostly idle, for example slack, gmail or tweetdeck. No
> significant
> packet rate is needed, just open connections.

No idea of what is going on really. A repro would be nice.