Intel's PowerTOP Extends Linux Battery Life
DuracellFan writes "Intel recently released its PowerTOP utility, which builds on work done by kernel developers to make the Linux kernel power-efficient. PowerTOP gives a snapshot of what apps are consuming the most power. The PowerTOP website also hosts patches for several Linux apps and the kernel. In the Linux.com article, lead PowerTOP developer Arjan van de Ven of Intel says that PowerTOP could soon show which applications keep the disk busy." Linux.com and Slashdot are both part of OSTG.
Doesn't really matter. You can make yourself a custom kernel just to check your apps and services with NO_HZ. Then when you've identified the misbehaving processes you can fix them and start using your old kernel again.
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Guess you could accuse him of bias...
Belief is the currency of delusion.
Definitely hard disk's activity is not a major contributor to power consumption. CPU usage is. Disks do require some juice to spin up (not that much though), but it's the CPU that makes the difference once the system is up and running. I know because this week I benchmarked precisely this issue: searching a file throughout the filesystem only raised consumption from 0.6 A to 0.65 A, but it went all the way up to 1.0 A when the CPU was at 100% (and at that point running the filesystem search did not raise consumption at all, indicating that the 0.05 A were due to CPU activity during file search and not to disk head moving or data flowing through the SCSI bus).
The biggest and easiest power savings come from CPU frequency scaling (if your processor supports it). Linux has long done a good pretty good job of putting the CPU to sleep and low power states when it can.
For older Athlon/Duron processors installing/running athcool makes a significant difference in power consumption (as long as it runs stable on your hardware, which it isn't guaranteed to do). On one of our old servers it reduced idle power draw from 100w to 65w.
It might depending on how idle your servers are. The more idle they are, the bigger the possibility for power savings. While they are obviously targeting laptop battery consumption, all Linux machines running this tool (and kernel 2.6.21 or later which has the dynticks feature) will be identify what is waking up their processor from low power states.
Much of the work put into optimizing battery life on laptops will also apply to desktops and servers alike.
I'm using NO_HZ on my P4 desktop. It was horrible in old patches, but the version in the mainline kernel (>= .20) is solid as a rock.
I gave the powertop thing a try the other day. Seems the worst offender on my machine is MPD, even when it's not doing anything.