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From: Thomas Gleixner <tglx@linutronix.de>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	linux-kernel@vger.kernel.org
Cc: "André Almeida" <andrealmeid@igalia.com>,
	"Darren Hart" <dvhart@infradead.org>,
	"Davidlohr Bueso" <dave@stgolabs.net>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Juri Lelli" <juri.lelli@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Valentin Schneider" <vschneid@redhat.com>,
	"Waiman Long" <longman@redhat.com>
Subject: Re: [RFC PATCH 0/3] futex: Add support task local hash maps.
Date: Sun, 27 Oct 2024 11:01:33 +0100	[thread overview]
Message-ID: <87froh50g2.ffs@tglx> (raw)
In-Reply-To: <20241026224306.982896-1-bigeasy@linutronix.de>

On Sun, Oct 27 2024 at 00:34, Sebastian Andrzej Siewior wrote:
> and adds support for task local futex_hash_bucket. It can be created via
> prctl() and each thread has to enable it via another prctl() interface.

That's a quick way to evaluate it.

> Individual threads may enable it but I guess this gets more complicated
> because the libc internal locks (or another lib) maybe be shared by
> multiple threads. So maybe it would be best to enable the local hash by
> the group leader and automatically enable for each thread on fork().

At the end we want to let the kernel automatically create the hash table
on first use of a private futex with a default size. That's a one off
latency. The prctl should only be there for preallocation and sizing.

And yes, you want to inherit when a new thread is created.

Thanks,

        tglx

      parent reply	other threads:[~2024-10-27 10:01 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-10-26 22:34 [RFC PATCH 0/3] futex: Add support task local hash maps Sebastian Andrzej Siewior
2024-10-26 22:34 ` [RFC PATCH 1/3] futex: Create helper function to initialize a hash slot Sebastian Andrzej Siewior
2024-10-26 22:34 ` [RFC PATCH 2/3] futex: Add basic infrastructure for local task local hash Sebastian Andrzej Siewior
2024-10-27 12:19   ` Thomas Gleixner
2024-10-28 10:30     ` Sebastian Andrzej Siewior
2024-10-28 10:58       ` Thomas Gleixner
2024-10-28 11:00         ` Peter Zijlstra
2024-10-28 12:02           ` Thomas Gleixner
2024-10-30 21:08             ` Peter Zijlstra
2024-10-30 23:14               ` Thomas Gleixner
2024-10-31  9:13                 ` Peter Zijlstra
2024-10-28 10:16   ` Peter Zijlstra
2024-10-28 10:24     ` Sebastian Andrzej Siewior
2024-10-28 10:46       ` Peter Zijlstra
2024-10-28 13:10         ` Peter Zijlstra
2024-10-26 22:34 ` [RFC PATCH 3/3] futex: Use the task local hashmap Sebastian Andrzej Siewior
2024-10-28 10:22   ` Peter Zijlstra
2024-10-28 10:24     ` Sebastian Andrzej Siewior
2024-10-27 10:01 ` Thomas Gleixner [this message]

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