Re: [PATCH 1/3] Dynamic sched domains: sched changes

[Matthew Dobson <colpatch@us.ibm.com>]

Dinakar Guniguntala wrote:
> Hello Andrew,
> 
> The following patches add dynamic sched domains functionality that was
> extensively discussed on lkml and lse-tech.
> I would like to see this added to -mm
> 
> o The main advantage with this feature is that it ensures that the scheduler
>   load balacing code only balances against the cpus that are in the sched
>   domain as defined by an exclusive cpuset and not all of the cpus in the
>   system. This removes any overhead due to load balancing code trying to
>   pull tasks outside of the cpu exclusive cpuset only to be prevented by
>   the tasks' cpus_allowed mask.
> o cpu exclusive cpusets are useful for servers running orthogonal
>   workloads such as RT applications requiring low latency and HPC
>   applications that are throughput sensitive
> 
> o It provides a new API partition_sched_domains in sched.c
>   that makes dynamic sched domains possible.
> o cpu_exclusive cpusets sets are now associated with a sched domain.
>   Which means that the users can dynamically modify the sched domains
>   through the cpuset file system interface
> o ia64 sched domain code has been updated to support this feature as well
> o Currently, this does not support hotplug. (However some of my tests
>   indicate hotplug+preempt is currently broken)
> o I have tested it extensively on x86.
> o This should have very minimal impact on performance as none of
>   the fast paths are affected
> 
>         -Dinakar
> 
> Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com>
> Acked-by: Paul Jackson <pj@sgi.com>
> Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
> 
>  linux-2.6.12-rc4-mm1-1/include/linux/sched.h     |    2
>  linux-2.6.12-rc4-mm1-1/kernel/sched.c            |  130 +++++++++++++++--------
>  linux-2.6.12-rc4-mm1-2/Documentation/cpusets.txt |   16 ++
>  linux-2.6.12-rc4-mm1-2/kernel/cpuset.c           |   89 +++++++++++++--
>  linux-2.6.12-rc4-mm1-3/arch/ia64/kernel/domain.c |   76 +++++++------
>  5 files changed, 225 insertions(+), 88 deletions(-)

Looks good to me, Dinakar!

Acked-by: Matthew Dobson <colpatch@us.ibm.com>

-Matt