Mystery load on my Arch Linux laptop

Posted on Sun 02 August 2015 in Linux

This weekend PyOhio was taking place at the Ohio State University Union building. While sitting in one of the presentations yesterday, I noticed that my battery was a bit lower than I expected. This also lead to me noticing that my load average was hovering between 1 and 1.5 despite having very little running on my computer. I started investigating. I stopped a lot of services & applications, rebooted, booted into rescue.target (systemd's "single user-ish" mode), etc... No matter what, the load was consistently above 1 no matter what.

After poking around for a while, I tried unloading the virtualbox kernel modules - vboxdrv, vboxnetflt, and vboxnetadp). My load started dropping like a bag of hammers. It looks like the problem driver is specifically vboxdrv:

[root@earth ~]# modprobe vboxdrv
[root@earth ~]# uptime
 13:34:34 up 22:17,  1 user,  load average: 0.06, 0.17, 0.14
[root@earth ~]# uptime
 13:34:45 up 22:17,  1 user,  load average: 0.20, 0.20, 0.14
[root@earth ~]# uptime
 13:35:46 up 22:19,  1 user,  load average: 1.00, 0.42, 0.22

As you can see, load just immediately starts climbing. Let's unload it!

[root@earth ~]# rmmod vboxdrv
[root@earth ~]# uptime
 13:59:57 up 22:43,  1 user,  load average: 0.99, 1.07, 0.92
[root@earth ~]# uptime
 14:00:17 up 22:43,  1 user,  load average: 0.71, 1.00, 0.91
[root@earth ~]# uptime
 14:02:42 up 22:45,  1 user,  load average: 0.08, 0.63, 0.78
[root@earth ~]# uptime
 14:02:58 up 22:46,  1 user,  load average: 0.06, 0.60, 0.77

And just like that, load returns to normal. I guess now's a good time to switch to libvirt!