diff options
| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2011-02-10 10:23:28 +0100 |
|---|---|---|
| committer | AK <andi@firstfloor.org> | 2011-03-31 11:58:02 -0700 |
| commit | 118de48b5183dbb3d6281302528ad1a93624854f (patch) | |
| tree | 8a63f75c5da1822edf0b0d0dcbf7aaf4434784f7 /include | |
| parent | 43c34b42474e03b54e11f6f17d87ce1160a83bc0 (diff) | |
sched: Use group weight, idle cpu metrics to fix imbalances during idle
Commit: aae6d3ddd8b90f5b2c8d79a2b914d1706d124193 upstream
Currently we consider a sched domain to be well balanced when the imbalance
is less than the domain's imablance_pct. As the number of cores and threads
are increasing, current values of imbalance_pct (for example 25% for a
NUMA domain) are not enough to detect imbalances like:
a) On a WSM-EP system (two sockets, each having 6 cores and 12 logical threads),
24 cpu-hogging tasks get scheduled as 13 on one socket and 11 on another
socket. Leading to an idle HT cpu.
b) On a hypothetial 2 socket NHM-EX system (each socket having 8 cores and
16 logical threads), 16 cpu-hogging tasks can get scheduled as 9 on one
socket and 7 on another socket. Leaving one core in a socket idle
whereas in another socket we have a core having both its HT siblings busy.
While this issue can be fixed by decreasing the domain's imbalance_pct
(by making it a function of number of logical cpus in the domain), it
can potentially cause more task migrations across sched groups in an
overloaded case.
Fix this by using imbalance_pct only during newly_idle and busy
load balancing. And during idle load balancing, check if there
is an imbalance in number of idle cpu's across the busiest and this
sched_group or if the busiest group has more tasks than its weight that
the idle cpu in this_group can pull.
Reported-by: Nikhil Rao <ncrao@google.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <1284760952.2676.11.camel@sbsiddha-MOBL3.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sched.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 0c2e5b5d02c..fc531a78012 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -856,6 +856,7 @@ struct sched_group { * single CPU. */ unsigned int cpu_power; + unsigned int group_weight; /* * The CPUs this group covers. |