6 ms·

Phoronix successfully git-bisects Linux power regressions for ~15% improvement

50 points by sandGorgon 15y ago

sandGorgon 15y ago
see if your laptop is affected - add "pcie_aspm=force" to your boot parameters. Ubuntu bug (updated) here - https://bugs.launchpad.net/ubuntu/+source/linux/+bug/760131 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/760131
kleiba 15y ago
A little bit ironic, if I understand the article correctly: Linux disables power management when the BIOS claims not to support it. But a lot of BIOS'es are misconfigured (intentionally) because otherwise Windows' power management wouldn't work. So, Linux - in trying to do things right - suffers indirectly from Windows' disabilities.
- FooBarWidget 15y ago
  A lot of hardware problems on Linux are like this. Unfortunately everybody still blame Linux.
  - eropple 15y ago
    As well they should. De facto standards, in this case Windows, are no less real than de jure ones. It sucks and it's unfair, but if you want compatibility, you target what exists.
- pavel_lishin 15y ago
  If doing things right means that things don't work, then you're not doing things right.
kevinburke 15y ago
So bisect only helps you find the commit that caused the regression, not the source code problem that caused the error?
- deleted 15y ago
  [deleted]
- Tuna-Fish 15y ago
  Yes, but because the best practise in git is to make commits very small, the commit that caused the regression is typically ~= the source code problem that caused the error.
- rmc 15y ago
  If you know the commit you know what lines of code it is. You're significantly narrowed down the code that is responsible.
- eru 15y ago
  Yes, because that would be a much harder problem to solve.
ChuckMcM 15y ago
I'll save you time and the amazing cat and mouse game of trying to move your mouse around that site without it popping up a half dozen advertisements ... (oh and its a giant advertisement for the Phoronix product) Power management sucks. Hardware vendors don't care that it sucks on Linux, they only care that it works on Windows. Microsoft pays people to make sure it works on Windows and browbeat manufacturers to make it work and they program around it on every platform where it doesn't work. In the 2.6.38 kernel a change was comitted into the mainline sources which chose 'probably works' over 'randomly hangs.' The fix was to stop trying to do power control and that means longevity is shorter (sometimes much shorter) Linux has maybe three people total (if you could somehow add up all the fractional people who care enough about this to work on it) who both understand how the latest invocation of power management works, and care enough to fix it for their system. Sometimes their fixes get into mainline, sometimes they live on some out of the way branch because someone on LKM didn't like them, sometimes you have to write to them to find out what they did. If you don't have a system where one of these fractional people made it work, you're screwed. This is the life you chose when you use Linux. This is true for lots of things Linux. I would love to help fix it (the fact that Linux sucks in the corners that aren't sexy) I don't know how yet. I'm open to suggestions. Google could do this (they use Linux on laptops) but they would only fix it for the corporate model/rev not for everything.
- wladimir 15y ago
  To be fair, though, not only Linux suffers from these problems, but all non-windows OSes. There is a standard for power management and such, ACPI, but vendors decide not to follow it but do their own thing and put in all kinds of hacks so that it works on windows and work around windows' problems. This means that specific work has to be done for every kind of device (and whitelist/blacklist it), which is a lot of extra hassle for the developers of the OS...
  - llambda 15y ago
    Is this true of Apple desktops as well? Or is Apple buddy-buddy enough with their hardware vendors that they get around this by receiving special treatment?

50 points by sandGorgon 15y ago

see if your laptop is affected - add "pcie_aspm=force" to your boot parameters. Ubuntu bug (updated) here - https://bugs.launchpad.net/ubuntu/+source/linux/+bug/760131 https://bugs.launchpad.net/ubuntu/+source/linux/+bug/760131

kleiba 15y ago

A little bit ironic, if I understand the article correctly: Linux disables power management when the BIOS claims not to support it. But a lot of BIOS'es are misconfigured (intentionally) because otherwise Windows' power management wouldn't work. So, Linux - in trying to do things right - suffers indirectly from Windows' disabilities.

FooBarWidget 15y ago
A lot of hardware problems on Linux are like this. Unfortunately everybody still blame Linux.
- eropple 15y ago
  As well they should. De facto standards, in this case Windows, are no less real than de jure ones. It sucks and it's unfair, but if you want compatibility, you target what exists.
pavel_lishin 15y ago
If doing things right means that things don't work, then you're not doing things right.

kevinburke 15y ago

So bisect only helps you find the commit that caused the regression, not the source code problem that caused the error?

deleted 15y ago
[deleted]
Tuna-Fish 15y ago
Yes, but because the best practise in git is to make commits very small, the commit that caused the regression is typically ~= the source code problem that caused the error.
rmc 15y ago
If you know the commit you know what lines of code it is. You're significantly narrowed down the code that is responsible.
eru 15y ago
Yes, because that would be a much harder problem to solve.

ChuckMcM 15y ago

I'll save you time and the amazing cat and mouse game of trying to move your mouse around that site without it popping up a half dozen advertisements ... (oh and its a giant advertisement for the Phoronix product) Power management sucks. Hardware vendors don't care that it sucks on Linux, they only care that it works on Windows. Microsoft pays people to make sure it works on Windows and browbeat manufacturers to make it work and they program around it on every platform where it doesn't work. In the 2.6.38 kernel a change was comitted into the mainline sources which chose 'probably works' over 'randomly hangs.' The fix was to stop trying to do power control and that means longevity is shorter (sometimes much shorter) Linux has maybe three people total (if you could somehow add up all the fractional people who care enough about this to work on it) who both understand how the latest invocation of power management works, and care enough to fix it for their system. Sometimes their fixes get into mainline, sometimes they live on some out of the way branch because someone on LKM didn't like them, sometimes you have to write to them to find out what they did. If you don't have a system where one of these fractional people made it work, you're screwed. This is the life you chose when you use Linux. This is true for lots of things Linux. I would love to help fix it (the fact that Linux sucks in the corners that aren't sexy) I don't know how yet. I'm open to suggestions. Google could do this (they use Linux on laptops) but they would only fix it for the corporate model/rev not for everything.

wladimir 15y ago
To be fair, though, not only Linux suffers from these problems, but all non-windows OSes. There is a standard for power management and such, ACPI, but vendors decide not to follow it but do their own thing and put in all kinds of hacks so that it works on windows and work around windows' problems. This means that specific work has to be done for every kind of device (and whitelist/blacklist it), which is a lot of extra hassle for the developers of the OS...
- llambda 15y ago
  Is this true of Apple desktops as well? Or is Apple buddy-buddy enough with their hardware vendors that they get around this by receiving special treatment?