LKML Archive on lore.kernel.org
 help / color / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Peter Oskolkov <posk@posk.io>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Ingo Molnar <mingo@kernel.org>,
	Darren Hart <dvhart@infradead.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Peter Oskolkov <posk@google.com>,
	Andrei Vagin <avagin@google.com>, Paul Turner <pjt@google.com>,
	Ben Segall <bsegall@google.com>, Aaron Lu <aaron.lwe@gmail.com>
Subject: Re: [PATCH for 5.9 1/3] futex: introduce FUTEX_SWAP operation
Date: Thu, 23 Jul 2020 13:27:57 +0200
Message-ID: <20200723112757.GN5523@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20200722234538.166697-2-posk@posk.io>

On Wed, Jul 22, 2020 at 04:45:36PM -0700, Peter Oskolkov wrote:
> This patchset is the first step to open-source this work. As explained
> in the linked pdf and video, SwitchTo API has three core operations: wait,
> resume, and swap (=switch). So this patchset adds a FUTEX_SWAP operation
> that, in addition to FUTEX_WAIT and FUTEX_WAKE, will provide a foundation
> on top of which user-space threading libraries can be built.

The PDF and video can go pound sand; you get to fully explain things
here.

What worries me is how FUTEX_SWAP would interact with the future
FUTEX_LOCK / FUTEX_UNLOCK. When we implement pthread_mutex with those,
there's very few WAIT/WAKE left.

Also, why would we commit to an ABI without ever having seen the rest?

On another note: wake_up_process_prefer_current_cpu() is a horrific
function name :/ That's half to a third of the line limit.

  reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22 23:45 [PATCH for 5.9 0/3] FUTEX_SWAP (tip/locking/core) Peter Oskolkov
2020-07-22 23:45 ` [PATCH for 5.9 1/3] futex: introduce FUTEX_SWAP operation Peter Oskolkov
2020-07-23 11:27   ` Peter Zijlstra [this message]
2020-07-24  0:25     ` Peter Oskolkov
2020-07-24  3:00       ` Waiman Long
2020-07-24  3:22         ` Peter Oskolkov
2020-07-27  9:51       ` peterz
2020-07-28  0:01         ` Peter Oskolkov
2020-07-22 23:45 ` [PATCH for 5.9 2/3] futex/sched: add wake_up_process_prefer_current_cpu, use in FUTEX_SWAP Peter Oskolkov
2020-07-22 23:45 ` [PATCH for 5.9 3/3] selftests/futex: add futex_swap selftest Peter Oskolkov

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=20200723112757.GN5523@worktop.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=aaron.lwe@gmail.com \
    --cc=avagin@google.com \
    --cc=bsegall@google.com \
    --cc=dvhart@infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=mingo@redhat.com \
    --cc=pjt@google.com \
    --cc=posk@google.com \
    --cc=posk@posk.io \
    --cc=tglx@linutronix.de \
    --cc=vincent.guittot@linaro.org \
    /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

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git
	git clone --mirror https://lore.kernel.org/lkml/8 lkml/git/8.git
	git clone --mirror https://lore.kernel.org/lkml/9 lkml/git/9.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git