Linux-GPIO Archive on lore.kernel.org
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From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Maxim Kochetkov <fido_max@inbox.ru>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>
Subject: Re: gpiolib gpio_chrdev_release duration is about 30 ms
Date: Fri, 17 Jul 2020 18:07:04 +0300
Message-ID: <CAHp75VfQdTtbiHjhBuf3czdKAgmiQeALo7CaqW36oEkSGSHUBA@mail.gmail.com> (raw)
In-Reply-To: <190bca20-946f-52f9-64f8-8971da17d38b@inbox.ru>

On Fri, Jul 17, 2020 at 5:17 PM Maxim Kochetkov <fido_max@inbox.ru> wrote:
>
> I need a small userspace program to do some GPIO magic to communicate
> other hardware like devmem. This program takes about 2,5 seconds just to
> find GPIO lines by name.
>
> replacing synchronize_rcu to synchronize_rcu_expedited in
> atomic_notifier_chain_unregister gives the same boost as removing
> synchronize_rcu

Have you tried to replace an atomic notifier call with a regular one?
IIRC it's still not clear why atomic is used there.

-- 
With Best Regards,
Andy Shevchenko

  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-17 12:56 Maxim Kochetkov
2020-07-17 13:37 ` Linus Walleij
2020-07-17 13:44   ` Maxim Kochetkov
2020-07-17 14:17   ` Maxim Kochetkov
2020-07-17 15:07     ` Andy Shevchenko [this message]
2020-07-18  4:25       ` Kent Gibson
2020-07-20  8:14         ` Maxim Kochetkov
2020-07-24 19:36           ` Bartosz Golaszewski
2020-07-25  3:52             ` Kent Gibson
2020-07-26 11:04               ` Bartosz Golaszewski
2020-07-26 22:32               ` Linus Walleij

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