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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 17 Jan 2018 13:54:32 -0800
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Subject: Re: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context
To:     David Miller <davem@davemloft.net>
Cc:     Mike Galbraith <efault@gmx.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Eric Dumazet <edumazet@google.com>,
        Dmitry Safonov <dima@arista.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Dmitry Safonov <0x7f454c46@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        Ingo Molnar <mingo@kernel.org>,
        Sasha Levin <alexander.levin@verizon.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Radu Rendec <rrendec@arista.com>,
        Rik van Riel <riel@redhat.com>,
        Stanislaw Gruszka <sgruszka@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Wanpeng Li <wanpeng.li@hotmail.com>
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On Wed, Jan 17, 2018 at 1:49 PM, David Miller <davem@davemloft.net> wrote:
>
>> That said, this made me wonder a bit. I wonder how bounded the latency
>> is for raising a softirq from process context. We only _check_ the
>> softirq on the last hardirq exit, I think.
>
> System call return checks it, otherwise this situation would be
> completely bolixed.

That's what I thought too. But then I went and looked, and I can't find it.

But you're probably right, and I just missed it.

              Linus