Ok, Here is the minimal patchset that I had promised after the
last discussion.

What it does have
o  The current patch enhances the meaning of exclusive cpusets by
   attaching them (exclusive cpusets) to sched domains
o  It does _not_ require any additional cpumask_t variable. It
   just parses the cpus_allowed of the parent/sibling/children
   cpusets for manipulating sched domains
o  All existing operations on non-/exclusive cpusets are preserved as-is.
o  The sched code has been modified to bring it upto 2.6.12-rc2-mm3

Usage
o  On setting the cpu_exclusive flag of a cpuset X, it creates two
   sched domains
   a. One, All cpus from X's parent cpuset that dont belong to any
      exclusive sibling cpuset of X
   b. Two, All cpus in X's cpus_allowed
o  On adding/deleting cpus to/from a exclusive cpuset X that has exclusive
   children, it creates two sched domains
   a. One, All cpus from X's parent cpuset that dont belong to any
      exclusive sibling cpuset of X
   b. Two, All cpus in X's cpus_allowed, after taking away any cpus that
      belong to exclusive child cpusets of X
o  On unsetting the cpu_exclusive flag of cpuset X or rmdir X, it creates a
   single sched domain, containing all cpus from X' parent cpuset that
   dont belong to any exclusive sibling of X and the cpus of X
o  It does _not_ modify the cpus_allowed variable of the parent as in the
   previous version. It relies on user space to move tasks to proper
   cpusets for complete isolation/exclusion
o  See function update_cpu_domains for more details

What it does not have
o  It is still short on documentation
o  Does not have hotplug support as yet
o  Supports only x86 as of now
o  No thoughts on "memory domains" (Though I am not sure, who
   would use such a thing and what exactly are the requirements)


Here is the increase in binary sizes for different values of CONFIG_NR_CPUS
(32 and 255)

kernel/cpuset.o.orig-32         16728
kernel/cpuset.o-v0.5-32         17176 (~2.7% increase)

kernel/cpuset.o.orig-255        17916
kernel/cpuset.o-v0.5-255        19120 (~6.7% increase)

The code changes are also minimal

 include/linux/init.h  |    2
 include/linux/sched.h |    1
 kernel/cpuset.c       |   73 +++++++++++++++++++++++++++------
 kernel/sched.c        |  109 +++++++++++++++++++++++++++++++++-----------------
 4 files changed, 134 insertions(+), 51 deletions(-)


        -Dinakar