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From: Sudeep Holla <sudeep.holla@arm.com>
To: Song Shuai <suagrfillet@gmail.com>
Cc: gregkh@linuxfoundation.org, rafael@kernel.org,
	conor.dooley@microchip.com, ionela.voinescu@arm.com,
	Pierre.Gondois@arm.com, Sudeep Holla <sudeep.holla@arm.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH V2] arch_topology: Clear LLC sibling when cacheinfo teardown
Date: Thu, 16 Mar 2023 09:29:10 +0000	[thread overview]
Message-ID: <20230316092910.doolw3xiuwwakile@bogus> (raw)
In-Reply-To: <20230314075345.1325187-1-suagrfillet@gmail.com>

On Tue, Mar 14, 2023 at 03:53:45PM +0800, Song Shuai wrote:
> The teardown of CPUHP_AP_BASE_CACHEINFO_ONLINE now only invokes
> free_cache_attributes() to clear share_cpu_map of cacheinfo list.
> At the same time, clearing cpu_topology[].llc_sibling is
> called quite late at the teardown code in hotplug STARTING section.
>
> To avoid the incorrect LLC sibling masks generated, move its clearing
> right after free_cache_attributes().
>

Technically in terms of flow/timing this is correct. However I would like
to know if you are seeing any issues without this change ?

Technically, if a cpu is hotplugged out, the cacheinfo is reset first
and then the topology. Until the cpu is removes, the LLC info in the
topology is still valid. Also I am not sure if anything gets scheduled
and this LLC info is utilised once the teardown of CPUHP_AP_BASE_CACHEINFO_ONLINE
has started.

So I am trying to understand if we really need this change. Please let me
know if I am missing anything here.

-- 
Regards,
Sudeep

  parent reply	other threads:[~2023-03-16  9:30 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-14  7:53 Song Shuai
2023-03-15 18:29 ` Conor Dooley
2023-03-16  9:29 ` Sudeep Holla [this message]
2023-03-16 10:30   ` Song Shuai
2023-03-16 14:50     ` Sudeep Holla
2023-03-20  6:20       ` Song Shuai
2023-03-20  7:20         ` Sudeep Holla

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