From: Andrew Morton <akpm@linux-foundation.org>
To: Len Brown <lenb@kernel.org>
Cc: linux-pm@lists.linux-foundation.org,
linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH] tools: add x86_energy_perf_policy to program MSR_IA32_ENERGY_PERF_BIAS
Date: Tue, 26 Oct 2010 20:23:07 -0700 [thread overview]
Message-ID: <20101026202307.c028e26c.akpm@linux-foundation.org> (raw)
In-Reply-To: <alpine.LFD.2.00.1010230035360.29399@localhost.localdomain>
On Sat, 23 Oct 2010 00:40:18 -0400 (EDT) Len Brown <lenb@kernel.org> wrote:
> MSR_IA32_ENERGY_PERF_BIAS first became available on Westmere Xeon.
> It is implemented in all Sandy Bridge processors -- mobile, desktop and server.
> It is expected to become increasingly important in subsequent generations.
>
> x86_energy_perf_policy is a user-space utility to set this
> hardware energy vs performance policy hint in the processor.
> Most systems would benefit from "x86_energy_perf_policy normal"
> at system startup, as the hardware default is maximum performance
> at the expense of energy efficiency. See the comments
> in the source code for more information.
>
> Linux-2.6.36 added "epb" to /proc/cpuinfo to indicate
> if an x86 processor supports MSR_IA32_ENERGY_PERF_BIAS,
> though the kernel does not actually program the MSR.
>
> In March, Venkatesh Pallipadi proposed a small driver
> that programmed MSR_IA32_ENERGY_PERF_BIAS, based on
> the cpufreq governor in use. It also offered
> a boot-time cmdline option to override.
> http://lkml.org/lkml/2010/3/4/457
> But hiding the hardware policy behind the
> governor choice was deemed "kinda icky".
>
> So in June, I proposed a generic user/kernel API to
> consolidate the power/performance policy trade-off.
> "RFC: /sys/power/policy_preference"
> http://lkml.org/lkml/2010/6/16/399
> That is my preference for implementing this capability,
> but I received no support on the list.
>
> So in September, I sent x86_energy_perf_policy.c to LKML,
> a user-space utility that scribbles directly to the MSR.
> http://lkml.org/lkml/2010/9/28/246
>
> Here is the same utility re-sent, this time proposed
> to reside in the kernel tools directory.
>
> Signed-off-by: Len Brown <len.brown@intel.com>
> ---
> tools/power/x86/x86_energy_perf_policy/Makefile | 7 +
> .../x86_energy_perf_policy.c | 358 ++++++++++++++++++++
> 2 files changed, 365 insertions(+), 0 deletions(-)
> create mode 100644 tools/power/x86/x86_energy_perf_policy/Makefile
> create mode 100644 tools/power/x86/x86_energy_perf_policy/x86_energy_perf_policy.c
tools/power/x86, eh? It seems a better place than under
Documentation/, where such things have thus far landed!
I looked briefly, wondering about the kbuild situation. It doesn't
appear to be wired up, so one has to manually enter that directory and
type `make'?
I guess that's OK as an interim thing but longer-term I suppose we
should have some more complete build and deployment system. So
(thinking out loud) a `make' would invoke a `make tools', and that
`make tools' would build the tools which are specific to the target
arch[*], and any generic ones. And a `make tools_install' would install
those tools in, I guess, /lib/modules/$(uname -r)/bin.
Or something else. We'd need input from the distro guys to get this
right.
[*]: building tools for the `target arch' would require a far more
extensive cross-build environment than is needed for just kernel
cross-compilation. This is perhaps Just Too Hard and perhaps a `make
tools_install' should copy the *source* into /lib/modules/$(uname
-r)/src and you then finish the build on the target. Or something
else. The mind boggles.
So for now, just parking the source down in ./tools/ and deferring the
problem sounds a fine idea ;)
A number of programs down under Documentation/ should be moved into
tools/ as well.
next prev parent reply other threads:[~2010-10-27 3:23 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-16 21:05 RFC: /sys/power/policy_preference Len Brown
2010-06-17 6:03 ` [linux-pm] " Igor.Stoppa
2010-06-17 19:00 ` Len Brown
2010-06-17 16:14 ` Victor Lowther
2010-06-17 19:02 ` Len Brown
2010-06-17 22:23 ` Victor Lowther
2010-06-18 5:56 ` Len Brown
2010-06-18 11:55 ` Victor Lowther
2010-06-19 15:17 ` Vaidyanathan Srinivasan
2010-06-19 19:04 ` Rafael J. Wysocki
2010-06-17 20:48 ` Mike Chan
2010-06-18 6:25 ` Len Brown
2010-06-21 20:10 ` [linux-pm] " Dipankar Sarma
2010-09-28 16:17 ` x86_energy_perf_policy.c Len Brown
2010-10-23 4:40 ` [PATCH] tools: add x86_energy_perf_policy to program MSR_IA32_ENERGY_PERF_BIAS Len Brown
2010-10-27 3:23 ` Andrew Morton [this message]
2010-10-27 6:01 ` Ingo Molnar
2010-10-27 11:43 ` Arnaldo Carvalho de Melo
2010-11-15 16:07 ` [PATCH RESEND] tools: add power/x86/x86_energy_perf_policy " Len Brown
2010-11-17 11:35 ` Andi Kleen
2010-11-22 20:13 ` Len Brown
2010-11-22 20:33 ` Andi Kleen
2010-11-23 4:48 ` Len Brown
2010-11-24 5:31 ` [PATCH v2] tools: create power/x86/x86_energy_perf_policy Len Brown
2010-11-25 5:52 ` Chen Gong
2010-11-25 8:59 ` Chen Gong
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