linux-kernel - Re: [PATCH v7 2/2] cpufreq: add virtual-cpufreq driver

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Message-ID: <Zx9rIjen30ArZd6k@bogus>
Date: Mon, 28 Oct 2024 10:44:50 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: David Dai <davidai@...gle.com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Rob Herring <robh@...nel.org>, Sudeep Holla <sudeep.holla@....com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Saravana Kannan <saravanak@...gle.com>,
	Quentin Perret <qperret@...gle.com>,
	Masami Hiramatsu <mhiramat@...gle.com>,
	Will Deacon <will@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Marc Zyngier <maz@...nel.org>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Pavan Kondeti <quic_pkondeti@...cinc.com>,
	Gupta Pankaj <pankaj.gupta@....com>, Mel Gorman <mgorman@...e.de>,
	kernel-team@...roid.com, linux-pm@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/2] cpufreq: add virtual-cpufreq driver

On Wed, Sep 18, 2024 at 05:08:33PM -0700, David Dai wrote:
> Introduce a virtualized cpufreq driver for guest kernels to improve
> performance and power of workloads within VMs.
> 
> This driver does two main things:
> 
> 1. Sends the frequency of vCPUs as a hint to the host. The host uses the
> hint to schedule the vCPU threads and decide physical CPU frequency.
> 
> 2. If a VM does not support a virtualized FIE(like AMUs), it queries the
> host CPU frequency by reading a MMIO region of a virtual cpufreq device
> to update the guest's frequency scaling factor periodically. This enables
> accurate Per-Entity Load Tracking for tasks running in the guest.
>

Acked-by: Sudeep Holla <sudeep.holla@....com>

-- 
Regards,
Sudeep