linux-kernel - Re: [PATCH v3 2/2] cpufreq: add virtual-cpufreq driver

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Message-ID: <20230804044219.ng26jwcomprguoi3@vireshk-i7>
Date:   Fri, 4 Aug 2023 10:12:19 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     David Dai <davidai@...gle.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        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 v3 2/2] cpufreq: add virtual-cpufreq driver

On 03-08-23, 09:50, David Dai wrote:
> > Why do you want to use this and not module_init() ? Then you can
> > simply use `module_platform_driver()`.
> 
> We found that using postcore_init over module_init results in a
> small(2-3%) but measurable benefit during boot time for VMs, so this
> is an optimization that I’d prefer to keep.

Okay. That's what platforms normally do (kick in cpufreq support
earlier), so we can boot at a higher frequency. Just wasn't sure if it
matters for this driver too.

-- 
viresh