linux-kernel - Re: [PATCH 3/3] sched: Disable affine wakeups by default

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Date:	Tue, 10 Nov 2009 22:59:29 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Mike Galbraith <efault@....de>, mingo@...e.hu,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/3] sched: Disable affine wakeups by default

On Sun, 2009-10-25 at 22:36 -0700, Arjan van de Ven wrote:
> 
> if you're a multicore domain you better have a shared cache.. that's
> what it should mean. If it does not we should fix that.

Fully agreed.. I've been dying to do the below for ages :-)

---
 arch/x86/kernel/smpboot.c |   10 +---------
 1 files changed, 1 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 213a7a3..297b307 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -433,15 +433,7 @@ void __cpuinit set_cpu_sibling_map(int cpu)
 const struct cpumask *cpu_coregroup_mask(int cpu)
 {
 	struct cpuinfo_x86 *c = &cpu_data(cpu);
-	/*
-	 * For perf, we return last level cache shared map.
-	 * And for power savings, we return cpu_core_map
-	 */
-	if ((sched_mc_power_savings || sched_smt_power_savings) &&
-	    !(cpu_has(c, X86_FEATURE_AMD_DCM)))
-		return cpu_core_mask(cpu);
-	else
-		return c->llc_shared_map;
+	return c->llc_shared_map;
 }
 
 static void impress_friends(void)


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