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 [thread overview]
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.
next prev parent reply other threads:[~2020-07-23 11:28 UTC|newest]
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
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