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Message-ID: <887fd1ba-c83f-77e4-74a9-53eef1dacc49@arm.com>
Date:   Thu, 31 Mar 2022 17:49:46 +0200
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Subject: Re: [PATCH v2] arch/arm64: Fix topology initialization for core
 scheduling
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To:     Phil Auld <pauld@redhat.com>
Cc:     linux-kernel@vger.kernel.org,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
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References: <20220330155611.30216-1-pauld@redhat.com>
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From:   Dietmar Eggemann <dietmar.eggemann@arm.com>
In-Reply-To: <20220331145343.GF17613@pauld.bos.csb>
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On 31/03/2022 16:53, Phil Auld wrote:
> On Thu, Mar 31, 2022 at 04:37:50PM +0200 Dietmar Eggemann wrote:
>> On 31/03/2022 15:21, Phil Auld wrote:
>>> On Thu, Mar 31, 2022 at 11:04:31AM +0200 Dietmar Eggemann wrote:
>>>> On 30/03/2022 17:56, Phil Auld wrote:

[...]

>> Yeah, maybe, it wouldn't hurt I guess. IMHO mentioning stress-ng's prctl
>> needs PR_SCHED_CORE support could also be handy since today's stress-ng
>> packages don't seem to have this yet.
>>
> 
> My scripts clone it so I did not realize that was not in prepackaged versions
> yet.  But that said, that's really just a way to tickle the problem. Anyone
> using core scheduling on such a system will hit this (at least the WARN part,
> the actual crash was harder to create w/o all the threads and tasks stress-ng
> uses).

OK.

I just saw that there is even a kselftest for this:

9f2699007493 - kselftest: Add test for core sched prctl interface
(2021-05-12 Chris Hyser)

But it doesn't trigger the issue.

> I can send a v3 with a further commit message update.

Sounds good.