Ubuntu
linux package

  1. Bug #188226
  2. Comment #5

Comment 5 for bug 188226

Revision history for this message
mannheim (kronheim) wrote :

A situation for which the currently configured kernel is poor is the following:

- a single-user desktop machine
- runs a scripted daily backup using, eg, tar and bz2 compression.

The backup script needs to run as root, to access files system wide. Because of the compression stage, the backup script is CPU intensive. The user's script runs with a large "nice" value. In the present configuration, although the user's desktop remains responsive while the backup runs, the backup process running as root takes a significant share of the CPU time, and affects any CPU-intensive task the user is running. If the kernel is recompiled with CONFIG_FAIR_CGROUP_SCHED, then the "nice" value has the desired effect and the backup script is unobstrusive.

I have verified this using hardy's 2.6.24-10-generic. Recompiling with CONFIG_FAIR_CGROUP_SCHED greatly increased the CPU share that the user's processes were given while the backup was running.

Anyway, the point of this post is to point out that things like boinc are far from the only cases where the present config has a downside. And unlike the boinc case, a systemwide backup cannot so easily be run as another user.