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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "André Almeida" <andrealmeid@collabora.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Darren Hart" <dvhart@infradead.org>,
	linux-kernel@vger.kernel.org,
	"Steven Rostedt" <rostedt@goodmis.org>,
	kernel@collabora.com, krisman@collabora.com,
	pgriffais@valvesoftware.com, z.figura12@gmail.com,
	joel@joelfernandes.org, malteskarupke@fastmail.fm,
	linux-api@vger.kernel.org, fweimer@redhat.com,
	libc-alpha@sourceware.org, linux-kselftest@vger.kernel.org,
	shuah@kernel.org, acme@kernel.org, corbet@lwn.net
Subject: Re: [RFC PATCH 01/13] futex2: Implement wait and wake functions
Date: Tue, 16 Feb 2021 11:20:44 +0100	[thread overview]
Message-ID: <20210216102044.e2cvvqdglqs23yfe@linutronix.de> (raw)
In-Reply-To: <YCuWvlKRXAygNQZP@hirez.programming.kicks-ass.net>

On 2021-02-16 10:56:14 [+0100], Peter Zijlstra wrote:
> So while I'm in favour of adding a new interface, I'm not sure I see
> benefit of reimplementing the basics, sure it seems simpler now, but
> that's because you've not implemented all the 'fun' stuff.

The last attempt tried to hide the updated interface within libc which
did not fly. The global hash state is one of the problems because it
leads to hash collisions of two unrelated locks.
It will get simpler if we go into the kernel for each lock/unlock
operation but this might not very good in terms of performance for locks
which are mostly uncontended. I'm not sure how much we can cheat in
terms of VDSO.

Sebastian

  reply	other threads:[~2021-02-16 10:23 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-15 15:23 [RFC PATCH 00/13] Add futex2 syscalls André Almeida
2021-02-15 15:23 ` [RFC PATCH 01/13] futex2: Implement wait and wake functions André Almeida
2021-02-15 19:59   ` Gabriel Krisman Bertazi
2021-02-18 13:29     ` André Almeida
2021-02-18 15:48       ` Gabriel Krisman Bertazi
2021-02-16  9:02   ` Peter Zijlstra
2021-02-18 20:09     ` André Almeida
2021-02-16  9:35   ` Peter Zijlstra
2021-02-16  9:56   ` Peter Zijlstra
2021-02-16 10:20     ` Sebastian Andrzej Siewior [this message]
2021-02-16 12:42       ` Peter Zijlstra
2021-02-16 22:12     ` Gabriel Krisman Bertazi
2021-02-15 15:23 ` [RFC PATCH 02/13] futex2: Add support for shared futexes André Almeida
2021-02-15 15:23 ` [RFC PATCH 03/13] futex2: Implement vectorized wait André Almeida
2021-02-15 20:03   ` Gabriel Krisman Bertazi
2021-02-15 20:06     ` Zebediah Figura
2021-02-15 20:08   ` Gabriel Krisman Bertazi
2021-02-15 15:23 ` [RFC PATCH 04/13] futex2: Implement requeue operation André Almeida
2021-02-15 15:23 ` [RFC PATCH 05/13] futex2: Add compatibility entry point for x86_x32 ABI André Almeida
2021-02-15 15:23 ` [RFC PATCH 06/13] docs: locking: futex2: Add documentation André Almeida
2021-02-16 18:34   ` Randy Dunlap
2021-02-18 19:12     ` André Almeida
2021-02-15 15:23 ` [RFC PATCH 07/13] selftests: futex2: Add wake/wait test André Almeida
2021-02-15 15:23 ` [RFC PATCH 08/13] selftests: futex2: Add timeout test André Almeida
2021-02-15 15:24 ` [RFC PATCH 09/13] selftests: futex2: Add wouldblock test André Almeida
2021-02-15 15:24 ` [RFC PATCH 10/13] selftests: futex2: Add waitv test André Almeida
2021-02-15 15:24 ` [RFC PATCH 11/13] selftests: futex2: Add requeue test André Almeida
2021-02-15 15:24 ` [RFC PATCH 12/13] perf bench: Add futex2 benchmark tests André Almeida
2021-02-15 15:24 ` [RFC PATCH 13/13] kernel: Enable waitpid() for futex2 André Almeida

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