From: Thomas Gleixner <tglx@linutronix.de>
To: Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org, io-uring@vger.kernel.org
Cc: peterz@infradead.org, oleg@redhat.com,
Jens Axboe <axboe@kernel.dk>, Roman Gershman <romger@amazon.com>
Subject: Re: [PATCH 4/4] task_work: use TIF_NOTIFY_SIGNAL if available
Date: Wed, 14 Oct 2020 01:50:25 +0200 [thread overview]
Message-ID: <87362hd6ta.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20201008152752.218889-5-axboe@kernel.dk>
On Thu, Oct 08 2020 at 09:27, Jens Axboe wrote:
> +/*
> + * TWA_SIGNAL signaling - use TIF_NOTIFY_SIGNAL, if available, as it's faster
> + * than TIF_SIGPENDING as there's no dependency on ->sighand. The latter is
> + * shared for threads, and can cause contention on sighand->lock. Even for
> + * the non-threaded case TIF_NOTIFY_SIGNAL is more efficient, as no locking
> + * or IRQ disabling is involved for notification (or running) purposes.
> + */
> +static void task_work_notify_signal(struct task_struct *task)
> +{
> +#ifdef TIF_NOTIFY_SIGNAL
> + set_notify_signal(task);
> +#else
> + unsigned long flags;
> +
> + /*
> + * Only grab the sighand lock if we don't already have some
> + * task_work pending. This pairs with the smp_store_mb()
> + * in get_signal(), see comment there.
> + */
> + if (!(READ_ONCE(task->jobctl) & JOBCTL_TASK_WORK) &&
> + lock_task_sighand(task, &flags)) {
> + task->jobctl |= JOBCTL_TASK_WORK;
> + signal_wake_up(task, 0);
> + unlock_task_sighand(task, &flags);
> + }
> +#endif
Same #ifdeffery comment as before.
Thanks,
tglx
next prev parent reply other threads:[~2020-10-14 9:24 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-08 15:27 [PATCHSET v4] Add support for TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-08 15:27 ` [PATCH 1/4] tracehook: clear TIF_NOTIFY_RESUME in tracehook_notify_resume() Jens Axboe
2020-10-13 23:35 ` Thomas Gleixner
2020-10-14 1:13 ` Jens Axboe
2020-10-08 15:27 ` [PATCH 2/4] kernel: add task_sigpending() helper Jens Axboe
2020-10-13 23:36 ` Thomas Gleixner
2020-10-08 15:27 ` [PATCH 3/4] kernel: add support for TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-09 14:43 ` Oleg Nesterov
2020-10-09 15:13 ` Jens Axboe
2020-10-13 23:45 ` Thomas Gleixner
2020-10-13 23:54 ` Jens Axboe
2020-10-13 23:42 ` Thomas Gleixner
2020-10-13 23:45 ` Jens Axboe
2020-10-08 15:27 ` [PATCH 4/4] task_work: use TIF_NOTIFY_SIGNAL if available Jens Axboe
2020-10-13 23:50 ` Thomas Gleixner [this message]
2020-10-13 23:55 ` Jens Axboe
2020-10-09 14:30 ` [PATCHSET v4] Add support for TIF_NOTIFY_SIGNAL Oleg Nesterov
2020-10-09 15:16 ` Jens Axboe
2020-10-16 15:45 [PATCHSET v6] " Jens Axboe
2020-10-16 15:45 ` [PATCH 4/4] task_work: use TIF_NOTIFY_SIGNAL if available Jens Axboe
2020-10-26 20:32 [PATCHSET v6a 0/4] Add support for TIF_NOTIFY_SIGNAL Jens Axboe
2020-10-26 20:32 ` [PATCH 4/4] task_work: use TIF_NOTIFY_SIGNAL if available Jens Axboe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87362hd6ta.fsf@nanos.tec.linutronix.de \
--to=tglx@linutronix.de \
--cc=axboe@kernel.dk \
--cc=io-uring@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=peterz@infradead.org \
--cc=romger@amazon.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.