On 02/15/2013 08:38 PM, Peter Zijlstra wrote:
> On Wed, 2013-02-13 at 21:22 +0800, Alex Shi wrote:
>> No, the flags set on MC/CPU domain, but is checked in their parents
>> balancing, like in NUMA domain.
>> Without the flag, will cause NUMA domain imbalance. like on my 2
>> sockets
>> NHM EP: 3 of 4 tasks were assigned on socket 0(lcpu, 10, 12, 14)
>>
>> In this case, update_sd_pick_busiest() need a reduced group_capacity
>> to
>> return true:
>> if (sgs->sum_nr_running > sgs->group_capacity)
>> return true;
>> then numa domain balancing get chance to start.
>
> Ah, indeed. Its always better to include such 'obvious' problems in the
> changelog :-)
>
got it. :)
how about the following commit log and patch:
---
>From c97fceceaf9d68e73eaf015d5915474a9a94a2d1 Mon Sep 17 00:00:00 2001
From: Alex Shi <alex....@intel.com>
Date: Fri, 28 Dec 2012 13:53:00 +0800
Subject: [PATCH] sched: set SD_PREFER_SIBLING on MC domain to reduce a domain
level
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 <efa...@gmx.de>
Signed-off-by: Alex Shi <alex....@intel.com>
---
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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