Current Linux CPU scheduler doesnt recognize process aggregates while
allocating bandwidth. As a result of this, an user could simply spawn large number of processes and get more bandwidth than others.
Here's a patch that provides fair allocation for all users in a system.
Some benchmark numbers with and without the patch applied follows:
user "vatsa" user "guest"
(make -s -j4 bzImage) (make -s -j20 bzImage)
2.6.20-rc5 472.07s (real) 257.48s (real)
2.6.20-rc5+fairsched 766.74s (real) 766.73s (real)
- breaks O(1) (ouch!)
Best way to avoid this is to split runqueue to be per-user and
per-cpu, which I have not implemented to keep the patch simple.
- Fairsched aware SMP load balance NOT addressed (yet)