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Windows CPU power settings

Gregory Szorc-3
I've been assessing new hardware options for Mozilla to issue to developers. As part of evaluating some dual socket Xeon processors, I found some unexpected behavior: these processors routinely underclock in Windows 10 unless several cores or are used. Contrast with the behavior of my i7 Skylake processor, which seems to ramp up to full clock pretty rapidly, even when only a single core is used.

The Windows 10 power settings appear to set the minimum CPU frequency at 5% or 10% of maximum. When I cranked this up to 100%, artifact build time dropped from ~170s to ~77s and full build configure dropped from ~165s to ~97s!

If you are a Windows user with Xeons in your desktop, you may want to visit Control Panel -> Hardware and Sound -> Power Options -> Edit Plan Settings -> Change advanced power settings -> Process power management -> Minimum processor state and crank that up and see what happens. Note: running your CPU at 100% all the time may impact your power bill!

Bug 1323106 has been opened to track improving the ability of the build system (namely `mach doctor`) to improve matters. If you would like to report success/failure of changing power settings or if you know a thing or two about CPU power management and can provide technical assistance, please weigh in there.

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Re: Windows CPU power settings

Ben Kelly
On Mon, Dec 12, 2016 at 8:44 PM, Gregory Szorc <[hidden email]> wrote:
The Windows 10 power settings appear to set the minimum CPU frequency at 5%
or 10% of maximum. When I cranked this up to 100%, artifact build time
dropped from ~170s to ~77s and full build configure dropped from ~165s to
~97s!

If you are a Windows user with Xeons in your desktop, you may want to visit
Control Panel -> Hardware and Sound -> Power Options -> Edit Plan Settings
-> Change advanced power settings -> Process power management -> Minimum
processor state and crank that up and see what happens. Note: running your
CPU at 100% all the time may impact your power bill!

FWIW, in my windows 10 Control Panel -> Hardware and Sound -> Power Options I had 3 preset power profiles:

* Balanced (default selected)
* Power Saver
* Performance

The "Balanced" profile has the 5% minimum clock speed.  The "Performance" profile set that to 100%.

Ben

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Re: Windows CPU power settings

Bobby Holley-2
It looks like there are similar (though not as bad) shenanigans on Linux.

In a fresh Ubuntu install, there are two available frequency governors, "powersave" and "performance". The default is "powersave", which seems suboptimal on a Desktop Xeon. The intel_pstate driver doesn't support manually pegging the clock, but the "performance" governor seems generous enough that it probably doesn't matter.

Installing cpufrequtils and then setting the governor in /etc/init.d/cpufrequtils to "performance" seemed to do the trick. You can get a live read on clock speeds with cpufreq-aperf, which should show all logical CPUs pegged to/near their max during a clobber build.

Changing this seemed to take a clobber build from 8:45 to 8:30, though I didn't remeasure in powersave.

HTH,
bholley

On Tue, Dec 13, 2016 at 6:31 AM, Ben Kelly <[hidden email]> wrote:
On Mon, Dec 12, 2016 at 8:44 PM, Gregory Szorc <[hidden email]> wrote:

> The Windows 10 power settings appear to set the minimum CPU frequency at 5%
> or 10% of maximum. When I cranked this up to 100%, artifact build time
> dropped from ~170s to ~77s and full build configure dropped from ~165s to
> ~97s!
>
> If you are a Windows user with Xeons in your desktop, you may want to visit
> Control Panel -> Hardware and Sound -> Power Options -> Edit Plan Settings
> -> Change advanced power settings -> Process power management -> Minimum
> processor state and crank that up and see what happens. Note: running your
> CPU at 100% all the time may impact your power bill!
>

FWIW, in my windows 10 Control Panel -> Hardware and Sound -> Power Options
I had 3 preset power profiles:

* Balanced (default selected)
* Power Saver
* Performance

The "Balanced" profile has the 5% minimum clock speed.  The "Performance"
profile set that to 100%.

Ben
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Re: Windows CPU power settings

Jim Blandy-2
On Fedora, that'd be the kernel-tools package, and the "cpupower frequency-info" command, I think?


On Sat, Dec 17, 2016 at 11:04 PM, Bobby Holley <[hidden email]> wrote:
It looks like there are similar (though not as bad) shenanigans on Linux.

In a fresh Ubuntu install, there are two available frequency governors,
"powersave" and "performance". The default is "powersave", which seems
suboptimal on a Desktop Xeon. The intel_pstate driver doesn't support
manually pegging the clock, but the "performance" governor seems generous
enough that it probably doesn't matter.

Installing cpufrequtils and then setting the governor in
/etc/init.d/cpufrequtils to "performance" seemed to do the trick. You can
get a live read on clock speeds with cpufreq-aperf, which should show all
logical CPUs pegged to/near their max during a clobber build.

Changing this seemed to take a clobber build from 8:45 to 8:30, though I
didn't remeasure in powersave.

HTH,
bholley

On Tue, Dec 13, 2016 at 6:31 AM, Ben Kelly <[hidden email]> wrote:

> On Mon, Dec 12, 2016 at 8:44 PM, Gregory Szorc <[hidden email]> wrote:
>
> > The Windows 10 power settings appear to set the minimum CPU frequency at
> 5%
> > or 10% of maximum. When I cranked this up to 100%, artifact build time
> > dropped from ~170s to ~77s and full build configure dropped from ~165s to
> > ~97s!
> >
> > If you are a Windows user with Xeons in your desktop, you may want to
> visit
> > Control Panel -> Hardware and Sound -> Power Options -> Edit Plan
> Settings
> > -> Change advanced power settings -> Process power management -> Minimum
> > processor state and crank that up and see what happens. Note: running
> your
> > CPU at 100% all the time may impact your power bill!
> >
>
> FWIW, in my windows 10 Control Panel -> Hardware and Sound -> Power Options
> I had 3 preset power profiles:
>
> * Balanced (default selected)
> * Power Saver
> * Performance
>
> The "Balanced" profile has the 5% minimum clock speed.  The "Performance"
> profile set that to 100%.
>
> Ben
> _______________________________________________
> dev-platform mailing list
> [hidden email]
> https://lists.mozilla.org/listinfo/dev-platform
>
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