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Date:   Sun, 21 Jan 2018 17:30:09 +0100
From:   Frederic Weisbecker <frederic@kernel.org>
To:     David Miller <davem@davemloft.net>
Cc:     torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
        alexander.levin@verizon.com, peterz@infradead.org,
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        sgruszka@redhat.com, riel@redhat.com, edumazet@google.com
Subject: Re: [RFC PATCH 1/4] softirq: Limit vector to a single iteration on
 IRQ tail
Message-ID: <20180121163008.GB2879@lerouge>
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On Fri, Jan 19, 2018 at 01:47:27PM -0500, David Miller wrote:
> From: Linus Torvalds <torvalds@linux-foundation.org>
> Date: Fri, 19 Jan 2018 10:25:03 -0800
> 
> > On Fri, Jan 19, 2018 at 8:16 AM, David Miller <davem@davemloft.net> wrote:
> >>
> >> So this "get requeued" condition I think will trigger always for
> >> networking tunnel decapsulation.
> > 
> > Hmm. Interesting and a perhaps bit discouraging.
> > 
> > Will it always be just a _single_ level of indirection, or will double
> > tunnels (I assume some people do that, just because the universe is
> > out to get us) then result in this perhaps repeating several times?
> 
> Every level of tunnel encapsulation will trigger a new softirq.
> 
> So if you have an IP tunnel inside of an IP tunnel that will trigger
> twice.

So we may likely need to come back to a call counter based limit :-s