Btrfs battery usage enhancement request

[ilker]

This is more of an enhancement request. Sorry I don't have detailed information other than below, but the main symptom is that:

The battery lasts almost about 20% less with the btrfs option on Ubuntu 17.10.

Below are some details of my experience (it is not very detailed or descriptive, but I am hoping other Ubuntu users might add their experiences, or more details)

I compared fresh installations of the following 3 setups. After fresh installs, all on Gnome, without any extensions or modifications (on a standard thinkpad kaby lake laptop with SSD).

1- Ubuntu 17.10 with ext4
2- Opensuse Leap 42.3 (Btrfs default)
3- Ubuntu 17.10 on Btrfs (btrfs snapshots enabled, and a few snapshots are taken)

Both 1 and 2 long term idle power usage is consistently at 3.5 watts/sec. However in 3 option it is 4.3 watts/sec. In my daily usage (3) is about 6.5hr (vs 8hr or even more. )

I really wanted to use new Ubuntu with Gnome so I did various tests on battery usage. The only difference seems to be that [btrfs-transactions] process writes more data and with a higher frequency (compared to Leap).

I couldn't see any other difference. For example, total CPU usage of all 3 are very similar almost identical per process. Additional watt/sec contribution of devices (such as blueetooth) are also identical.

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1736570/+editstatus and add the package name in the text box next to the word Package.

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