From: "Christoph Lameter (Ampere)" <cl@gentwo.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
mingo@redhat.com, dvhart@infradead.org, dave@stgolabs.net,
andrealmeid@igalia.com,
Andrew Morton <akpm@linux-foundation.org>,
urezki@gmail.com, hch@infradead.org, lstoakes@gmail.com,
Arnd Bergmann <arnd@arndb.de>,
linux-api@vger.kernel.org, linux-mm@kvack.org,
linux-arch@vger.kernel.org, malteskarupke@web.de,
llong@redhat.com
Subject: Re: [PATCH 2/6] futex: Implement FUTEX2_NUMA
Date: Mon, 28 Oct 2024 15:37:15 -0700 (PDT) [thread overview]
Message-ID: <50dc2133-5f43-3a02-38a9-234e8acb5b8c@gentwo.org> (raw)
In-Reply-To: <20241028094618.GL9767@noisy.programming.kicks-ass.net>
On Mon, 28 Oct 2024, Peter Zijlstra wrote:
> Using get_task_policy() seems very dangerous to me. It is explicitly
> possible for different tasks in a process to have different policies,
> which means (private) futexes would fail to work correctly.
>
> We need something that is process wide consistent -- like the vma
> policies. Except at current, those are to expensive to readily access.
The vma policies are bound to addresses that in turn yields address space
wide validity.
However, different threads may run on processes on different nodes and
therefore having different numa nodes close to them etc.
next prev parent reply other threads:[~2024-10-28 22:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-25 9:03 [PATCH 0/6] futex: The remaining futex2 bits Peter Zijlstra
2024-10-25 9:03 ` [PATCH 1/6] mm: Add vmalloc_huge_node() Peter Zijlstra
2024-10-25 9:58 ` Uladzislau Rezki
2024-10-25 16:00 ` Davidlohr Bueso
2024-10-25 9:03 ` [PATCH 2/6] futex: Implement FUTEX2_NUMA Peter Zijlstra
2024-10-25 18:30 ` Davidlohr Bueso
2024-10-28 9:38 ` Peter Zijlstra
2024-10-25 19:28 ` Christoph Lameter (Ampere)
2024-10-28 1:59 ` Davidlohr Bueso
2024-10-28 22:34 ` Christoph Lameter (Ampere)
2024-10-28 9:46 ` Peter Zijlstra
2024-10-28 22:37 ` Christoph Lameter (Ampere) [this message]
2024-10-25 21:23 ` André Almeida
2024-10-25 9:03 ` [PATCH 3/6] futex: Propagate flags into futex_get_value_locked() Peter Zijlstra
2024-10-25 9:03 ` [PATCH 4/6] futex: Enable FUTEX2_{8,16} Peter Zijlstra
2024-10-25 9:03 ` [PATCH 5/6] futex,selftests: Extend the futex selftests Peter Zijlstra
2024-10-25 9:03 ` [PATCH 6/6] futex,selftests: Extend the futex selftests for NUMA Peter Zijlstra
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