From: Tycho Andersen <tycho@tycho.pizza>
To: Andrei Vagin <avagin@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
linux-kernel@vger.kernel.org, Kees Cook <keescook@chromium.org>,
Christian Brauner <brauner@kernel.org>,
Andrei Vagin <avagin@gmail.com>,
Andy Lutomirski <luto@amacapital.net>,
Juri Lelli <juri.lelli@redhat.com>,
Peter Oskolkov <posk@google.com>, Will Drewry <wad@chromium.org>
Subject: Re: [PATCH 4/5] seccomp: add the synchronous mode for seccomp_unotify
Date: Thu, 12 Jan 2023 08:00:25 -0700 [thread overview]
Message-ID: <Y8AgiZqYSjozXbhP@tycho.pizza> (raw)
In-Reply-To: <20230110213010.2683185-5-avagin@google.com>
On Tue, Jan 10, 2023 at 01:30:09PM -0800, Andrei Vagin wrote:
> From: Andrei Vagin <avagin@gmail.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 to the target
> process. In this context, "synchronous" means that only one process is
> running and another one is waiting.
>
> There is the WF_CURRENT_CPU flag that is used to advise 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 12µs. With this patch, it takes about
> 3µs.
>
> This change introduce the SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP flag that
> it used to enable the sync mode.
What about just not having a flag and using the new primitives all the
time? Is there any reason not to?
Tycho
next prev parent reply other threads:[~2023-01-12 15:12 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-10 21:30 [PATCH 0/5 v3 RESEND] seccomp: add the synchronous mode for seccomp_unotify Andrei Vagin
2023-01-10 21:30 ` [PATCH 1/5] seccomp: don't use semaphore and wait_queue together Andrei Vagin
2023-01-12 14:58 ` Tycho Andersen
2023-01-13 21:51 ` Andrei Vagin
2023-01-16 9:48 ` Peter Zijlstra
2023-01-10 21:30 ` [PATCH 2/5] sched: add WF_CURRENT_CPU and externise ttwu Andrei Vagin
2023-01-12 7:35 ` Chen Yu
2023-01-13 21:39 ` Andrei Vagin
2023-01-14 15:59 ` Chen Yu
2023-01-18 6:10 ` Andrei Vagin
2023-01-10 21:30 ` [PATCH 3/5] sched: add a few helpers to wake up tasks on the current cpu Andrei Vagin
2023-01-16 9:59 ` Peter Zijlstra
2023-01-19 6:45 ` Andrei Vagin
2023-01-19 10:09 ` Peter Zijlstra
2023-01-10 21:30 ` [PATCH 4/5] seccomp: add the synchronous mode for seccomp_unotify Andrei Vagin
2023-01-12 15:00 ` Tycho Andersen [this message]
2023-01-14 1:16 ` Andrei Vagin
2023-01-10 21:30 ` [PATCH 5/5] selftest/seccomp: add a new test for the sync mode of seccomp_user_notify Andrei Vagin
-- strict thread matches above, loose matches on Subject: below --
2022-11-11 7:31 [PATCH 0/5 v3] seccomp: add the synchronous mode for seccomp_unotify Andrei Vagin
2022-11-11 7:31 ` [PATCH 4/5] " Andrei Vagin
2022-10-20 1:10 [PATCH 0/5 v2] " Andrei Vagin
2022-10-20 1:10 ` [PATCH 4/5] " Andrei Vagin
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