linux-kernel - Re: [PATCH 0/5 v3] seccomp: add the synchronous mode for seccomp

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Date:   Mon, 21 Nov 2022 23:52:11 -0800
From:   Andrei Vagin <avagin@...il.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     Andrei Vagin <avagin@...gle.com>,
        Christian Brauner <brauner@...nel.org>,
        linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...capital.net>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Peter Oskolkov <posk@...gle.com>,
        Tycho Andersen <tycho@...ho.pizza>,
        Will Drewry <wad@...omium.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 0/5 v3] seccomp: add the synchronous mode for seccomp_unotify

On Fri, Nov 18, 2022 at 2:38 PM Kees Cook <keescook@...omium.org> wrote:
>
> On Thu, Nov 10, 2022 at 11:31:49PM -0800, Andrei Vagin wrote:
> > From: Andrei Vagin <avagin@...il.com>
> >
> > seccomp_unotify allows more privileged processes do actions on behalf
> > of less privileged processes.
> >
> > In many cases, the workflow is fully synchronous. It means a target
> > process triggers a system call and passes controls to a supervisor
> > process that handles the system call and returns controls back to the
> > target process. In this context, "synchronous" means that only one
> > process is running and another one is waiting.
> >
> > The new WF_CURRENT_CPU flag advises the scheduler to move the wakee to
> > the current CPU. For such synchronous workflows, it makes context
> > switches a few times faster.
> >
> > Right now, each interaction takes 12盜. With this patch, it takes about
> > 3盜.
> >
> > v2: clean up the first patch and add the test.
> > v3: update commit messages and a few fixes suggested by Kees Cook.
>
> Thanks for the update! If I can get Acks from the sched folks, I think
> this looks good to take.

Peter, Ingo, could you take a look at this series?

Thanks,
Andrei