On Sun, Sep 07, 2008 at 03:20:56PM -0300, Ivan Baldo wrote:
The CGROUP infrastructure is the only way to allow runtime configuration
on how the scheduler should work, so some simple DebConf questions could
setup the system as the user wants it (even distribution between users, even
distribution between groups, even distribution for all the processes without
considering groups or users), and even after that, a user or sysadmin could
further configure it.
Which configuration option is removed due to the group scheduler? I fail
to find any.
Currently, the FAIR_GROUP_SCHED option is the worst choice, because of 2
things:
1 - it forces one behaviour and there is no other way but recompile
the kernel to change it.
No. It only extends the scheduler decision with another information.
2 - it changes a default behaviour used for many years! you may run a
program with nice 19 and SCHED_IDLEPRIO and still consume a lot
of CPU time and starve other processes. Users and sysadmins are
used to the nice command to control priorities of processes
without thinking about groupings by group or user id.
Please show that behaviour. By default a system have only one group and
within the group the default nice behaviour is used. Between groups the
cpu is uniformly distributed.
Proove:
| $ ps ux | grep test
| USER 15850 86.1 0.0 1740 336 pts/6 RN 22:05 0:12 ./test-nice-10
| USER 15851 11.3 0.0 1740 336 pts/6 RN 22:05 0:01 ./test-nice-19
| $ uname -a
| Linux HOST 2.6.26-1-powerpc64 #1 SMP Mon Aug 25 00:33:17 UTC 2008 ppc64 GNU/Linux
Both processes runs in a cgroup which is restricted to one cpu.
Bastian