[conspire] idle computer

[Tony Godshall]

Modern CPUs already can conserve power by going to a lower clock speed
without sleeping, so I don't know that you'd save much power that way,
esp. if you like to run things in background.  Here's how you can see
what speeds your CPUs support and what speed they are are at:

$ grep . /proc/acpi/processor/CPU*/throttling

I like to run CPU Frequency Scaling Monitor in my gnome sessions to
see watch the speed pop up and down on demand (right click on panel,
add to panel, ...)  As I type this my old laptop with a great screen
is popping up to 1.4Gz periodially most mostly hovering at 600MHz.

Hard drives, having motors, consume more power.  As do displays.  Have
those power down when not in use.  But also be aware that power surges
are another reason things fail, so don't configure so things power up
and down too repeatedly.

Solid state hard drives take a lot less power- consider them.


On Tue, Jul 19, 2011 at 1:31 PM, Paul Zander <paulz at ieee.org> wrote:
> Thank you for the replies. Personally, I have not been "hibernating", but gathering information (and also busy with other tasks).
>
> TERSE
> ACPI as well as screen savers, including SETI and BOINC, apparently determines idle from lack of I/O, especially keyboard and mouse, but sometimes also LAN traffic.
>
> I will consider nice and ionice if I choose to support BOINC or similar projects.
>
> From www.energystar.gov,   “ saving $25–75 per PC annually “ So this is not a big deal if $$ are all that matter.
>
> I am interested in comments regarding hard-drives. Hard drives do make noticeable noise in a quite home. My opinion is that stopping mechanical devices should reduce wear and improve life, but I don't have any data to support that opinion. Others think drives should be kept running. In any event, disk drives don't consume much power.  More under VERBOSE.
>
>
> VERBOSE
> I did a series of experiments looking at the power management settings using XP, Live DVD LMDE and installed LMDE. After sorting out the differences in wording, the setting values are different. I won't fault the creators of the live DVD for doing a simplified version. Next time I install, I will try to remember “step 0: Set power management to Never.”
>
> So far I have not found the official definition of “idle”, but I did find few descriptions. All relate to I/O and not to CPU usage.
>
>  * Idle-ness is defined by an absence of mouse or keyboard activity
>
>  * Accomplishing power management has four components. The first is to monitor activity levels of the processor, input devices (such as the keyboard and mouse), and communication peripherals (network or modem)
>
>  * Someone who spends a lot of time reading on screen will need a longer delay period than someone who spends most of their time typing.
>
> I did find several reports from university IT departments. Some encouraging powering down at night, others wanting computers turned on so they could be updated during the night. Neither of these apply to me.
>
> From www.energystar.gov regarding hard-drives:
>  * and some studies indicate it would require on-off cycling every five minutes to harm a hard drive."
> Source: Rocky Mountain Institute Home Energy Brief #7 Computers and Peripherals.
>
>  * "The belief that frequent shutdowns are harmful persists from the days when hard disks did not automatically park their heads when shut off; frequent on-off cycling could damage such hard disks. Conventional wisdom, however, has not kept pace with the rapid technological change in the computer industry. Modern hard disks are not significantly affected by frequent shutdowns."
> Source: "User Guide to Power Management for PCs and Monitors", Bruce Nordman, Lawrence Berkeley National Laboratory, January, 1997, LBNL-39466
>
>
> --- On Thu, 7/14/11, Tony Godshall <tony at of.net> wrote:
>
> From: Tony Godshall <tony at of.net>
> Subject: Re: [conspire] idle computer
> To: "Rick Moen" <rick at linuxmafia.com>
> Cc: conspire at linuxmafia.com
> Date: Thursday, July 14, 2011, 5:08 PM
>
> ...
>>  nohup ./seti &
>>
>> ...then change that to
>>
>>  nohup nice ./seti &
>>
>> The 'nice' utility, part of GNU coreutils, accepts numerical values for
>> additional niceness (reduced runtime priority) to assign to tasks at the
>> time they start up.  I would guess this information is passed in some
>> fashion as a request to the kernel's scheduler.
>>
>> 'nice' defaults to a +10 adjustment, i.e., just 'nice' is the same as
>> 'nice -n 10'.
> ...
>
> ionice -c3 is good too... it helps in cases where the process does
> heavy io with low CPU use (like copying files)
>
> apt-get install ionice
>
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-- 
Best Regards.
This is unedited.
P-)