linux-kernel - Re: [PATCH v5 00/24] ARM64 PMU Partitioning

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Message-ID: <aTiqK7gKKKzGGwgW@kernel.org>
Date: Tue, 9 Dec 2025 15:00:59 -0800
From: Oliver Upton <oupton@...nel.org>
To: Colton Lewis <coltonlewis@...gle.com>
Cc: kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Russell King <linux@...linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Mingwei Zhang <mizhang@...gle.com>, Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Mark Rutland <mark.rutland@....com>, Shuah Khan <shuah@...nel.org>,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-perf-users@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v5 00/24] ARM64 PMU Partitioning

On Tue, Dec 09, 2025 at 08:50:57PM +0000, Colton Lewis wrote:
> This series creates a new PMU scheme on ARM, a partitioned PMU that
> allows reserving a subset of counters for more direct guest access,
> significantly reducing overhead. More details, including performance
> benchmarks, can be read in the v1 cover letter linked below.
> 
> An overview of what this series accomplishes was presented at KVM
> Forum 2025. Slides [1] and video [2] are linked below.
> 
> The long duration between v4 and v5 is due to time spent on this
> project being monopolized preparing this feature for internal
> production. As a result, there are too many improvements to fully list
> here, but I will cover the notable ones.

Thanks for reposting. I think there's still quite a bit of ground to
cover on the KVM side of this, but I would definitely appreciate it if
someone with more context on the perf side of things could chime in.

Will, IIRC you had some thoughts around counter allocation, right?

Best,
Oliver