[tip:sched/balancing] sched: Turn on SD_WAKE_IDLE for 'close' domains

tip-bot for Ingo Molnar
2009-09-04T10:26:19Z

Commit-ID: e54c7073fae0683b90b3157e97142202c7334b79
Gitweb: http://git.kernel.org/tip/e54c7073fae0683b90b3157e97142202c7334b79
Author: Ingo Molnar <mingo@elte.hu>
AuthorDate: Fri, 4 Sep 2009 11:38:07 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Fri, 4 Sep 2009 12:17:06 +0200

sched: Turn on SD_WAKE_IDLE for 'close' domains

Turn it on for the thread, core and cpu domain defaults.

Same argument as for NEWIDLE: we want to err on the side of
over-balancing, and mute the effect of that when it hurts
a workload.

On a NUMA box (4x4) i get better CPU utilization:

Performance counter stats for './hackbench 10' (10 runs):

Before: 2124.478000 task-clock-msecs # 12.196 CPUs ( +- 0.614% )
After: 2232.558805 task-clock-msecs # 12.601 CPUs ( +- 0.852% )

It's probably not worth turning it on for the NUMA domain though,
as even on this fast-NUMA box it's break-even in terms of cost
versus improvement:

After #2: 2288.062034 task-clock-msecs # 12.909 CPUs ( +- 0.864% )

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
include/linux/topology.h | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/linux/topology.h b/include/linux/topology.h
index 66774fd..f13ff3a 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -95,7 +95,7 @@ int arch_update_cpu_topology(void);
| 1*SD_BALANCE_NEWIDLE \
| 1*SD_BALANCE_EXEC \
| 1*SD_BALANCE_FORK \
- | 0*SD_WAKE_IDLE \
+ | 1*SD_WAKE_IDLE \
| 1*SD_WAKE_AFFINE \
| 1*SD_WAKE_BALANCE \
| 1*SD_SHARE_CPUPOWER \
@@ -129,7 +129,7 @@ int arch_update_cpu_topology(void);
| 1*SD_BALANCE_NEWIDLE \
| 1*SD_BALANCE_EXEC \
| 1*SD_BALANCE_FORK \
- | 0*SD_WAKE_IDLE \
+ | 1*SD_WAKE_IDLE \
| 1*SD_WAKE_AFFINE \
| 1*SD_WAKE_BALANCE \
| 0*SD_SHARE_CPUPOWER \
@@ -163,7 +163,7 @@ int arch_update_cpu_topology(void);
| 1*SD_BALANCE_NEWIDLE \
| 1*SD_BALANCE_EXEC \
| 1*SD_BALANCE_FORK \
- | 0*SD_WAKE_IDLE \
+ | 1*SD_WAKE_IDLE \
| 0*SD_WAKE_AFFINE \
| 1*SD_WAKE_BALANCE \
| 0*SD_SHARE_CPUPOWER \