[PATCH] sched: set SD_PREFER_SIBLING on MC domain to reduce a domainlevel

[Alex Shi]

The domain flag SD_PREFER_SIBLING was set both on MC and CPU domain at
frist commit b5d978e0c7e79a, and was removed in-carefully when clear up
obsolete power scheduler. Then commit 6956dc568 recover the flag on CPU
domain only. It works, but it introduces a extra domain level since this
cause MC/CPU different.

So, recover the the flag in MC domain too to remove a domain level in
x86 platform.

This flag can not be removed since it is used to keep parent domain
balancing, like in NUMA domain, update_sd_pick_busiest() need a reduced
group_capacity to return 'true' then re-balance tasks from groups.

Reported-by: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Alex Shi <alex.shi@xxxxxxxxx>
---
 include/linux/topology.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/linux/topology.h b/include/linux/topology.h
index d3cf0d6..386bcf4 100644
--- a/include/linux/topology.h
+++ b/include/linux/topology.h
@@ -132,6 +132,7 @@ int arch_update_cpu_topology(void);
 				| 0*SD_SHARE_CPUPOWER			\
 				| 1*SD_SHARE_PKG_RESOURCES		\
 				| 0*SD_SERIALIZE			\
+				| 1*SD_PREFER_SIBLING			\
 				,					\
 	.last_balance		= jiffies,				\
 	.balance_interval	= 1,					\
-- 
1.7.5.4


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