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From: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Rutland <mark.rutland@arm.com>,
	"Christoph Lameter (Ampere)" <cl@gentwo.org>
Cc: Will Deacon <will@kernel.org>,
	Jonathan.Cameron@huawei.com,
	Matteo.Carlini@arm.com,
	akpm@linux-foundation.org,
	anshuman.khandual@arm.com,
	Eric Mackay <eric.mackay@oracle.com>,
	dave.kleikamp@oracle.com,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	linux-mm@kvack.org,
	linux@armlinux.org.uk,
	robin.murphy@arm.com,
	vanshikonda@os.amperecomputing.com,
	yang@os.amperecomputing.com,
	Valentin Schneider <vschneid@redhat.com>
Subject: Re: [PATCH v3] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512
Date: Thu,  7 Mar 2024 19:07:07 +0000
Message-Id: <170983839495.1825460.8461454086733296317.b4-ty@arm.com>
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On Wed, 06 Mar 2024 17:45:04 -0800, Christoph Lameter (Ampere) wrote:
> Currently defconfig selects NR_CPUS=256, but some vendors (e.g. Ampere
> Computing) are planning to ship systems with 512 CPUs. So that all CPUs on
> these systems can be used with defconfig, we'd like to bump NR_CPUS to 512.
> Therefore this patch increases the default NR_CPUS from 256 to 512.
> 
> As increasing NR_CPUS will increase the size of cpumasks, there's a fear that
> this might have a significant impact on stack usage due to code which places
> cpumasks on the stack. To mitigate that concern, we can select
> CPUMASK_OFFSTACK. As that doesn't seem to be a problem today with
> NR_CPUS=256, we only select this when NR_CPUS > 256.
> 
> [...]

Applied to arm64 (for-next/misc), thanks!

I dropped the config entry and comment, replaced it with a select as per
Mark's suggestion.

[1/1] ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512
      https://git.kernel.org/arm64/c/0499a78369ad

-- 
Catalin