From: Thomas Gleixner <tglx@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-kernel@vger.kernel.org,
"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>,
"Valentin Schneider" <vschneid@redhat.com>,
"Waiman Long" <longman@redhat.com>
Subject: Re: [PATCH v8 03/15] futex: Add basic infrastructure for local task local hash.
Date: Tue, 04 Feb 2025 10:28:11 +0100 [thread overview]
Message-ID: <87ldumnjo4.ffs@tglx> (raw)
In-Reply-To: <20250204084135.GN7145@noisy.programming.kicks-ass.net>
On Tue, Feb 04 2025 at 09:41, Peter Zijlstra wrote:
> On Mon, Feb 03, 2025 at 04:52:51PM +0100, Sebastian Andrzej Siewior wrote:
>> On 2025-02-03 15:41:01 [+0100], Peter Zijlstra wrote:
>> > Notably, I'm also still thikning about all that pending FUTEX2_NUMA
>> > stuff.
>>
>> With local-hash there is still room for FUTEX2_NUMA?
>
> Yes, single process can span multiple nodes, and then you still get the
> cross node contention issues.
This is strictly about process private futexes, while FUTEX2_NUMA covers
both shared and private futexes and helps to avoid the hash collision
and resulting contention problems which are caused by the current global
hash.
With the private futex seperation you obviously get the cross node
memory access problems, but not the general contention issues which
FUTEX2_NUMA tries to address.
Thanks,
tglx
next prev parent reply other threads:[~2025-02-04 9:28 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-03 13:59 [PATCH v8 00/15] futex: Add support task local hash maps Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 01/15] rcuref: Avoid false positive "imbalanced put" report Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 02/15] futex: Create helper function to initialize a hash slot Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 03/15] futex: Add basic infrastructure for local task local hash Sebastian Andrzej Siewior
2025-02-03 14:27 ` Peter Zijlstra
2025-02-03 15:51 ` Sebastian Andrzej Siewior
2025-02-04 10:34 ` Peter Zijlstra
2025-02-05 8:39 ` Sebastian Andrzej Siewior
2025-02-07 9:41 ` Juri Lelli
2025-02-07 11:00 ` Sebastian Andrzej Siewior
2025-02-07 11:06 ` Peter Zijlstra
2025-02-07 14:47 ` Juri Lelli
2025-02-03 14:29 ` Peter Zijlstra
2025-02-03 14:41 ` Peter Zijlstra
2025-02-03 15:39 ` Peter Zijlstra
2025-02-03 15:52 ` Sebastian Andrzej Siewior
2025-02-04 8:41 ` Peter Zijlstra
2025-02-04 9:28 ` Thomas Gleixner [this message]
2025-02-03 13:59 ` [PATCH v8 04/15] futex: Allow automatic allocation of process wide futex hash Sebastian Andrzej Siewior
2025-02-03 14:36 ` Peter Zijlstra
2025-02-03 15:54 ` Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 05/15] futex: Hash only the address for private futexes Sebastian Andrzej Siewior
2025-02-03 14:41 ` Peter Zijlstra
2025-02-03 13:59 ` [PATCH v8 06/15] futex: Move private hashing into its own function Sebastian Andrzej Siewior
2025-02-04 9:34 ` Peter Zijlstra
2025-02-05 7:51 ` Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 07/15] futex: Decrease the waiter count before the unlock operation Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 08/15] futex: Prepare for reference counting of the process private hash end of operation Sebastian Andrzej Siewior
2025-02-04 9:49 ` Peter Zijlstra
2025-02-05 7:54 ` Sebastian Andrzej Siewior
2025-02-05 9:37 ` Peter Zijlstra
2025-02-03 13:59 ` [PATCH v8 09/15] futex: Re-evaluate the hash bucket after dropping the lock Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 10/15] futex: Introduce futex_get_locked_hb() Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 11/15] futex: Acquire a hash reference in futex_wait_multiple_setup() Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 12/15] futex: Allow to re-allocate the private local hash Sebastian Andrzej Siewior
2025-02-04 11:05 ` Peter Zijlstra
2025-02-05 8:00 ` Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 13/15] futex: Resize local futex hash table based on number of threads Sebastian Andrzej Siewior
2025-02-04 10:21 ` Peter Zijlstra
2025-02-05 8:05 ` Sebastian Andrzej Siewior
2025-02-07 9:07 ` Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 14/15] futex: Use a hashmask instead of hashsize Sebastian Andrzej Siewior
2025-02-03 13:59 ` [PATCH v8 15/15] futex: Avoid allocating new local hash if there is something pending Sebastian Andrzej Siewior
2025-02-04 15:14 ` [PATCH v8 00/15] futex: Add support task local hash maps Peter Zijlstra
2025-02-05 8:46 ` Sebastian Andrzej Siewior
2025-02-05 12:20 ` Sebastian Andrzej Siewior
2025-02-05 12:52 ` Peter Zijlstra
2025-02-05 16:52 ` Sebastian Andrzej Siewior
2025-02-20 15:12 ` Peter Zijlstra
2025-02-20 15:57 ` Sebastian Andrzej Siewior
2025-02-21 16:00 ` Sebastian Andrzej Siewior
2025-02-21 19:21 ` Peter Zijlstra
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