Another Major Linux Power Regression Spotted

[Michael]

And would that be a Dunkles Weißbier?

No, just some Hacker-Pschorr. I was low on beer and busy with this testing so just walked to a store that's a block away to pickup some Hacker where as otherwise the beer I normally drink is about six kilometers away. So I was just being efficient and drinking slightly-less-good-but-still-amazing Munich beer.

[mthome]

Normally, using more power, to the extent that it's correlated with increased performance, is a "good thing" for servers and other computers running on A/C power.

That might be true on workstations, but is certainly not the case for rack-dense servers where THE problem is maximizing performance per watt, both from energy cost and problems of heat dissipation. Perhaps I'm missing something, but how is this bug not driving the server people nuts? 15% greater power consumption at idle would massive problem in a server farm, let alone cloud server containers.

[locovaca]

That might be true on workstations, but is certainly not the case for rack-dense servers where THE problem is maximizing performance per watt, both from energy cost and problems of heat dissipation. Perhaps I'm missing something, but how is this bug not driving the server people nuts? 15% greater power consumption at idle would massive problem in a server farm, let alone cloud server containers.

Because most server people aren't running a Beta OS, let alone a bleeding edge kernel, on a production hardware. You're seeing why

[richo123]

This bug has been open on the Ubuntu bugzilla (Launchpad) for two years

https://bugs.launchpad.net/ubuntu/+s...ux/+bug/524281

The only way to get it fixed is for someone to attract the kernel developers attention.....

These test results should be added to with some powertop runs and results reported. I am beyond frustration over this matter. It reflects very badly on linux.

[mthome]

Because most server people aren't running a Beta OS, let alone a bleeding edge kernel, on a production hardware. You're seeing why

Hmm - well, while Ubuntu 10.10 isn't LTS, it isn't beta either, and kernel 2.6.35 is supposed to be production quality (with longterm support). In any case, my point is that I'm surprised that this is still being portrayed as an issue that mainly applies to laptop users when it is precluding anything more recent than 2.6.34 from running on the server side - the traditional linux stronghold.

[richo123]

This issue has been in the Ubuntu Launchpad system for two years now:

https://bugs.launchpad.net/bugs/524281

It needs reporting to the kernel bugzilla. The results here plus powertop output would be good. Someone familiar with kernel development needs to do this (not me unfortunately).

[locovaca]

Hmm - well, while Ubuntu 10.10 isn't LTS, it isn't beta either, and kernel 2.6.35 is supposed to be production quality (with longterm support). In any case, my point is that I'm surprised that this is still being portrayed as an issue that mainly applies to laptop users when it is precluding anything more recent than 2.6.34 from running on the server side - the traditional linux stronghold.

RHEL 6 is running 2.6.32. Ubuntu 10.04 LTS is at 2.6.32. Nobody is running 10.10 on a serious server farm without special needs, no matter how long the individual kernel package is going to be supported by upstream. In 2 years that's not going to matter because Ubuntu will sunset 10.10.

[devius]

[Offtopic] Idea for PTS: ability to zoom in graphs.

I recently discovered a bug in my wifi adapter that causes terrible performance with power management activated. This started around the time the kernel I'm running got updated to 2.6.38, so it seems the power management area really needs a bit more attention.

[Michael]

[Offtopic] Idea for PTS: ability to zoom in graphs.

When using the SVG version it should work so fine.

[dargllun]

Maybe I'm just stating the obvious but have you compared the kernel .config files with each other? For instance, if the default config starts using a higher CONFIG_HZ setting you'll have a much different amount of ticker timer irqs, and, potentially, task reschedulings happening. Same with CONFIG_HZ vs tickerless modes etc. Just a thought.