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Message-Id: <1219252901.8651.63.camel@twins>
Date: Wed, 20 Aug 2008 19:21:41 +0200
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
To: Ray Lee <ray-lk@...rabbit.org>
Cc: Nick Piggin <nickpiggin@...oo.com.au>, adobriyan@...il.com,
Ingo Molnar <mingo@...e.hu>,
"Zhang, Yanmin" <yanmin_zhang@...ux.intel.com>,
Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>,
Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
Aneesh Kumar KV <aneesh.kumar@...ux.vnet.ibm.com>,
Balbir Singh <balbir@...ibm.com>,
Chris Friesen <cfriesen@...tel.com>
Subject: Re: VolanoMark regression with 2.6.27-rc1
Ok, so one last time (I hope!)..
Everybody happy with this?
---
Subject: sched: load-balance bias fixes
From: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Date: Wed Aug 20 15:28:51 CEST 2008
Yanmin spotted a regression with my patch that introduces LB_BIAS:
commit 93b75217df39e6d75889cc6f8050343286aff4a5
Author: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Date: Fri Jun 27 13:41:33 2008 +0200
And I just spotted the brainfart - I should have replaced min/max with avg
instead of removing it completely.
[ray-lk@...rabbit.org: better avg implementation]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
include/linux/kernel.h | 6 ++++++
kernel/sched.c | 10 ++++++++--
2 files changed, 14 insertions(+), 2 deletions(-)
Index: linux-2.6/kernel/sched.c
===================================================================
--- linux-2.6.orig/kernel/sched.c
+++ linux-2.6/kernel/sched.c
@@ -2008,9 +2008,12 @@ static unsigned long source_load(int cpu
struct rq *rq = cpu_rq(cpu);
unsigned long total = weighted_cpuload(cpu);
- if (type == 0 || !sched_feat(LB_BIAS))
+ if (type == 0)
return total;
+ if (!sched_feat(LB_BIAS))
+ return avg(rq->cpu_load[type-1], total);
+
return min(rq->cpu_load[type-1], total);
}
@@ -2023,9 +2026,12 @@ static unsigned long target_load(int cpu
struct rq *rq = cpu_rq(cpu);
unsigned long total = weighted_cpuload(cpu);
- if (type == 0 || !sched_feat(LB_BIAS))
+ if (type == 0)
return total;
+ if (!sched_feat(LB_BIAS))
+ return avg(rq->cpu_load[type-1], total);
+
return max(rq->cpu_load[type-1], total);
}
Index: linux-2.6/include/linux/kernel.h
===================================================================
--- linux-2.6.orig/include/linux/kernel.h
+++ linux-2.6/include/linux/kernel.h
@@ -367,6 +367,12 @@ static inline char *pack_hex_byte(char *
(void) (&_max1 == &_max2); \
_max1 > _max2 ? _max1 : _max2; })
+#define avg(x, y) ({ \
+ typeof(x) _avg1 = (x); \
+ typeof(y) _avg2 = (y); \
+ (void) (&_avg1 == &_avg2); \
+ _avg1 + (_avg2 - _avg1)/2; })
+
/**
* clamp - return a value clamped to a given range with strict typechecking
* @val: current value
--
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