linux-kernel - Re: [PATCH v7 0/2] Improve VM CPUfreq and task placement behavior

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Message-ID: <CAGETcx8GomM0znaYKsS412dRvnUQd7_78pKuV82t2b14VBvKVQ@mail.gmail.com>
Date: Fri, 25 Oct 2024 15:25:19 -0700
From: Saravana Kannan <saravanak@...gle.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: David Dai <davidai@...gle.com>, "Rafael J. Wysocki" <rafael@...nel.org>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Sudeep Holla <sudeep.holla@....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 0/2] Improve VM CPUfreq and task placement behavior

On Tue, Oct 1, 2024 at 2:25 AM Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> On 18-09-24, 17:08, David Dai wrote:
> > Hi,
> >
> > This patch series is a continuation of the talk Saravana gave at LPC 2022
> > titled "CPUfreq/sched and VM guest workload problems" [1][2][3]. The gist
> > of the talk is that workloads running in a guest VM get terrible task
> > placement and CPUfreq behavior when compared to running the same workload
> > in the host. Effectively, no EAS(Energy Aware Scheduling) for threads
> > inside VMs. This would make power and performance terrible just by running
> > the workload in a VM even if we assume there is zero virtualization
> > overhead.
>
> > David Dai (2):
> >   dt-bindings: cpufreq: add virtual cpufreq device
> >   cpufreq: add virtual-cpufreq driver
> >
> >  .../cpufreq/qemu,virtual-cpufreq.yaml         |  48 +++
> >  drivers/cpufreq/Kconfig                       |  14 +
> >  drivers/cpufreq/Makefile                      |   1 +
> >  drivers/cpufreq/virtual-cpufreq.c             | 333 ++++++++++++++++++
> >  include/linux/arch_topology.h                 |   1 +
> >  5 files changed, 397 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/cpufreq/qemu,virtual-cpufreq.yaml
> >  create mode 100644 drivers/cpufreq/virtual-cpufreq.c
>
> LGTM.
>
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

Rafael/Viresh,

Nudge... Any chance this will get pulled into 6.12?

Thanks,
Saravana