There are tidbits elsewhere in our forum on this possible Power Management regression topic, so I thought I would start a thread in ‘chat-chat’ on this, to consolidate the information. This is NOT a help request thread, and if one wants help, then this thread is NOT the place.
There have been a series of articles on the Phoronix web site, which have suggested regressions in the Linux kernel
- during the 2.6.37 to 2.6.38 and
- during the 2.6.34 to 2.6.35
with the 2.6.34 to 2.6.35 being discovered last.
Some quotes from the Phoronix web site posts …
FIRST, the 2.6.37 to 2.6.28 possible regression was discovered: [Phoronix] Mobile Users Beware: Linux Has Major Power Regression](http://www.phoronix.com/scan.php?page=article&item=linux_mobile_uffda&num=1) where they state:
During the Linux 2.6.38 kernel development, a regression was introduced causing systems to burn through significantly more power. … On the particular system being talked about in the article today is the power consumption going up by 14%, which would lead to a noticeably shorter battery life. … The Linux 2.6.35/2.6.36/2.6.37 results are virtually identical, but with 2.6.38 is where the regression strikes. As far as the Linux 2.6.39 results, it shows the regression still present. …
SECOND, the 2.6.34 to 2.6.35 possible regression, discovered [Phoronix] Another Major Linux Power Regression Spotted](http://www.phoronix.com/scan.php?page=article&item=linux_kernel_regress2&num=1) after Phoronix upgraded their benchmarks and paid more attention to power management in the results. Also, the 2.6.34 to 2.6.35 possible regression appeared worse than the 2.6.37 to 2.6.38.
With this expanded round of power testing, the Linux 2.6.37 to Linux 2.6.38 regression is still shown, but it also uncovered a very noticeable differentiation in power consumption between the Linux 2.6.34 and 2.6.35 kernels too. Under idle on this test system, it equates to a 20% difference in power consumption and then the 2.6.37/2.6.38 regression tacks on another 6% in this particular test profile.
… The pre-2.6.35 kernels are all running at right around the same power level within a reasonable milliwatt range of each other on the various tests. … However, with the Linux 2.6.35 kernel, the power consumption goes up noticeably.
Now the above is all from Phoronix. I can not recall other blogs or Linux articles posting about this with independent confirmation, although I do recall some openSUSE-11.4 users complaining about their battery laptop life. Unfortunately I can’t find those threads to see if what they observed ‘might’ fall into this possible kernel regression category.
Have any openSUSE-11.4 (2.6.37 kernel) or Tumbleweed-11.4 (2.6.38 kernel) users noted this decrease in battery life on their laptops with those Linux versions ?
Note this is not a thread for complaints / rants. I have moderator permissions and I will delete any rants that might follow this post. I prefer simple observations, not negative insulting judgments about what ‘may’ have happened wrt power management. Thank you.