Linux vs. Windows Power Usage
Phoronix: Linux vs. Windows Power Usage
Since publishing our Ubuntu power tests, where we had monitored the power consumption of the past six Ubuntu releases going back two years on a laptop, we've had repeated requests for a power comparison between Windows and different Linux distributions. Well, in this article are the first set of results from that testing. We've compared the power consumption of Microsoft Windows XP, Windows Vista, Fedora 7, and Ubuntu 7.10.
tests procedure suggestions
You might try testing with:
1. idle + folding@home
2. idle + playing the same video and/or audio file
3. idle + scripted FTP activity with a server on your LAN (for more controlled latencies)
4. idle + grep on a file
You'll probably want to test each of these plenty of times and have a little bit of idle time before and after the action is added to the idle state. Measure a constant amount of time that fully contains the action ie. type out "grep [Pp]attern file.txt" on a com.exe or terminal window, wait a minute, start power consumption measurement, and then hit enter and wait for just a little longer than the greatest amount of time it could take before stopping the measurement.
Also since different machines have different power saving abilities testing on multiple machines would be good.
fix the bugs!
Did your testing reveal any particular reasons for the results? I bet your machine is generating a lot of spurious interrupts in Linux, just like mine does.
I think a better job should be done in hunting down and patching the programs that don't let the processor sleep. My poor laptop is still chewing 1-2% CPU even when it's doing nothing at all.
Powertop shows many culprits, the powertop folks know what the offenders are, and they submit bug reports, but the bugs languish for months. Why? I recently submitted a Fedora bug with a patch, and it was fixed and pushed to production in just a few days. What gives?
Frankly, I believe the desktop users are the last group of people who are concerning about the power usage of their machine. The power consumption has a much larger impact on servers or laptops. I am not saying that testing the power consumption difference between Linux and Windows on a Northwood machine is completely useless, but I just think most desktop user won't care if their desktop is consuming 58watt or 61watt of power under normal usage.
90% of the time I boot into Ubuntu Gutsy on my Thinkpad T61p. However during traveling, I always boot into Windows XP instead of Ubuntu because XP gives me one additional hour of battery life than Ubuntu. I heard that the 2.6.22 kernel has some feature to reduce the CPU power consumption by reduce the number of CPU wakeups, but I have never noticed the difference. When considering battery life, XP eats Linux for breakfast.
Aren't these benchmarks rather pointless? Running laptops on AC means automatic power saving won't kick in. This means that you cannot gauge how long one OS will take to run down the battery vs. another.
Originally Posted by phoronix
This Test Is Meaningless
Testing the power usage of Linux vs Windows is futile at best. First of all, you could have optimised either platform to use less power. Assuming that you turn off all services, and underclock and undervolt the CPU. Linux ( any distro you choose ) has the advantage of being able to separate the GUI, so you can run it in a non-graphical runlevel and with no services, use a different kernel CPU governor ... and Windows will not be able to compete. However what is the purpose of this machine? Where are the real world tests or did this entire idea come to you while sitting on the porcelean throne after this mornings breakfast?
What is the point of this test? Are you just trying to compare default installation power usages or what?
Also, I would recommend using a method that gives you ( when dealing with watts ) at least 3 decimal places of accuracy.
hack an ammeter in between the battery and laptop and run your test off ac.
Actually don't bother:
$ cat /proc/acpi/battery/C175/state
capacity state: ok
charging state: discharging
present rate: 1376 mA
remaining capacity: 3669 mAh
present voltage: 12114 mV
That's from a hp nx6125.
There's your data, can you get the same in windoze?
Don't trust any power data the laptop tells you. There's no way to verify its accuracy. Use a meter attached to the mains.
Originally Posted by lewis
Good But Still a Little Whimpish
Good for first start but still a little whimpish.... It's really sad when people are afraid of seeing their favorite distro performing badly.
The whole point is to compare the two similar setups (as much as possible). In Ubuntu's case, Compiz should be enabled, as most users will want Vista's 3D effects... Also, whatever services that provide a similar Windows service should be left running...like cups, etc. The idea is also to compare a "sane" setup---a system that the average user would want.
I would imagine power usage gives a hint of what to expect performance wise. The more power usage the slower...I imagine that that's usually true...
accurately measure battery current
If you really want to get an accurate reading of how much current is drawn from the battery, you'll have to get between the battery and the laptop. The best way I can think of to do that is to get an extra battery, rip out its guts, solder wires to the terminals inside the battery pack, and run the wires out to another battery. Now you can get in there with an ammeter and measure the true current draw. You have to at least verify what the laptop's internal current sensor is telling you. Otherwise it could be wildly inaccurate and you'd have no way of knowing.