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Subject: Re: [PATCH 2/2] PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs
 interface
To:     "Rafael J. Wysocki" <rjw@rjwysocki.net>, x86 <x86@kernel.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Len Brown <len.brown@intel.com>,
        Linux PM <linux-pm@vger.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Laura Abbott <labbott@fedoraproject.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Simon Schricker <sschricker@suse.de>,
        Borislav Petkov <bp@suse.de>
References: <1637073.gl2OfxWTjI@aspire.rjw.lan>
 <1762575.ER2xjzr9E1@aspire.rjw.lan>
From:   Hannes Reinecke <hare@suse.de>
Message-ID: <1fa29c73-c756-6942-76e5-0273efefd446@suse.de>
Date:   Fri, 22 Mar 2019 10:03:57 +0100
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On 3/21/19 11:20 PM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> 
> The Performance and Energy Bias Hint (EPB) is expected to be set by
> user space through the generic MSR interface, but that interface is
> not particularly nice and there are security concerns regarding it,
> so it is not always available.
> 
> For this reason, add a sysfs interface for reading and updating the
> EPB, in the form of a new attribute, energy_perf_bias, located
> under /sys/devices/system/cpu/cpu#/power/ for online CPUs that
> support the EPB feature.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>   Documentation/ABI/testing/sysfs-devices-system-cpu |   18 ++++
>   Documentation/admin-guide/pm/intel_epb.rst         |   27 ++++++
>   arch/x86/kernel/cpu/intel_epb.c                    |   93 ++++++++++++++++++++-
>   3 files changed, 134 insertions(+), 4 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@suse.com>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
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