linux-kernel - Re: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context

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Message-ID: <CA+55aFwmvoz0MQGdwC+bNh40SEDTXt2F_rJuPr3CxpX_O+jo=w@mail.gmail.com>
Date:   Wed, 17 Jan 2018 13:54:32 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     David Miller <davem@...emloft.net>
Cc:     Mike Galbraith <efault@....de>,
        Peter Zijlstra <peterz@...radead.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Dmitry Safonov <dima@...sta.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Dmitry Safonov <0x7f454c46@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Hannes Frederic Sowa <hannes@...essinduktion.org>,
        Ingo Molnar <mingo@...nel.org>,
        Sasha Levin <alexander.levin@...izon.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Radu Rendec <rrendec@...sta.com>,
        Rik van Riel <riel@...hat.com>,
        Stanislaw Gruszka <sgruszka@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [RFC 1/2] softirq: Defer net rx/tx processing to ksoftirqd context

On Wed, Jan 17, 2018 at 1:49 PM, David Miller <davem@...emloft.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