From: Kurt Kanzenbach via Libc-alpha <libc-alpha@sourceware.org>
To: libc-alpha@sourceware.org
Cc: Florian Weimer <fweimer@redhat.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Joseph Myers <joseph@codesourcery.com>
Subject: Re: [PATCH v1 0/6] nptl: Introduce and use FUTEX_LOCK_PI2
Date: Fri, 09 Jul 2021 08:57:46 +0200 [thread overview]
Message-ID: <87h7h47z4l.fsf@kurt> (raw)
In-Reply-To: <20210625081104.1134598-1-kurt@linutronix.de>
[-- Attachment #1: Type: text/plain, Size: 1585 bytes --]
On Fri Jun 25 2021, Kurt Kanzenbach wrote:
> Linux real time applications often make use of mutexes with priority inheritance
> enabled due to problems such as unbounded priority inversion. In addition, some
> applications make use of timeouts e.g., by utilizing pthread_mutex_clocklock().
>
> However, the combination of priority inheritance enabled mutexes with timeouts
> based on CLOCK_MONOTONIC doesn't work. That is because the underlying Linux
> kernel futex interface didn't support it, yet. Using CLOCK_REALTIME is possible,
> but it is subject to adjustments (NTP, PTP, ...). Therefore, Thomas proposed and
> introduced a new futex operation called FUTEX_LOCK_PI2 with support for
> selectable clocks [1].
>
> Here is a proof of concept patch set adding FUTEX_LOCK_PI2 in order to support
> pthread_mutex_clocklock(MONOTONIC)/PI. The idea is to use futex_lock_pi2() by
> default, and fallback to futex_lock_pi() in case the kernel is too old.
>
> There's also a bugreport for glibc with a test case:
>
> https://sourceware.org/bugzilla/show_bug.cgi?id=26801
>
> Changes since RFC:
>
> * FUTEX_LOCK_PI2 merged in upstream Linux kernel (Thomas Gleixner, Peter Zijlstra)
> * Make of __ASSUME_FUTEX_LOCK_PI2 in the implementation (Adhemerval Zanella)
> * Get rid of probing for FUTEX_LOCK_PI2 in timedlock (Adhemerval Zanella)
> * Adjust the test cases (Adhemerval Zanella)
> * Use correct Linux kernel version (Joseph Myers)
>
> Previous versions:
>
> * https://sourceware.org/pipermail/libc-alpha/2021-June/127798.html
Ping. Any comments on this version?
Thanks,
Kurt
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 861 bytes --]
next prev parent reply other threads:[~2021-07-09 6:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-25 8:10 [PATCH v1 0/6] nptl: Introduce and use FUTEX_LOCK_PI2 Kurt Kanzenbach via Libc-alpha
2021-06-25 8:10 ` [PATCH v1 1/6] Linux: Add FUTEX_LOCK_PI2 Kurt Kanzenbach via Libc-alpha
2021-07-09 13:32 ` Adhemerval Zanella via Libc-alpha
2021-06-25 8:11 ` [PATCH v1 2/6] nptl: Introduce futex_lock_pi2() Kurt Kanzenbach via Libc-alpha
2021-07-09 14:13 ` Adhemerval Zanella via Libc-alpha
2021-06-25 8:11 ` [PATCH v1 3/6] nptl: Use futex_lock_pi2() Kurt Kanzenbach via Libc-alpha
2021-07-09 14:21 ` Adhemerval Zanella via Libc-alpha
2021-06-25 8:11 ` [PATCH v1 4/6] nptl: Remove mutex test 10 Kurt Kanzenbach via Libc-alpha
2021-07-09 14:23 ` Adhemerval Zanella via Libc-alpha
2021-06-25 8:11 ` [PATCH v1 5/6] nptl: mutex-test5: Include CLOCK_MONOTONIC for PI Kurt Kanzenbach via Libc-alpha
2021-06-25 8:11 ` [PATCH v1 6/6] nptl: mutex-test9: " Kurt Kanzenbach via Libc-alpha
2021-07-09 6:57 ` Kurt Kanzenbach via Libc-alpha [this message]
2021-07-09 13:30 ` [PATCH v1 0/6] nptl: Introduce and use FUTEX_LOCK_PI2 Adhemerval Zanella via Libc-alpha
2021-07-09 14:20 ` Kurt Kanzenbach via Libc-alpha
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
List information: https://www.gnu.org/software/libc/involved.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87h7h47z4l.fsf@kurt \
--to=libc-alpha@sourceware.org \
--cc=bigeasy@linutronix.de \
--cc=fweimer@redhat.com \
--cc=joseph@codesourcery.com \
--cc=kurt@linutronix.de \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).