[PATCH 2/2] x86: Move x86_cpu_to_apicid to the __read_mostly section

[Vlad Zolotarov]

From: Shai Fultheim <shai@xxxxxxxxxxx>

x86_cpu_to_apicid is only written to during initialization. Benchmarks
show that moving it to the __read_mostly section helps avoid false
sharing on large multiprocessing systems.

Signed-off-by: Shai Fultheim <shai@xxxxxxxxxxx>
Signed-off-by: Vlad Zolotarov <vlad@xxxxxxxxxxx>
---
 arch/x86/include/asm/smp.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 0434c40..b9d6c1e 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -53,7 +53,7 @@ static inline struct cpumask *cpu_llc_shared_mask(int cpu)
 	return per_cpu(cpu_llc_shared_map, cpu);
 }
 
-DECLARE_EARLY_PER_CPU(u16, x86_cpu_to_apicid);
+DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid);
 DECLARE_EARLY_PER_CPU(u16, x86_bios_cpu_apicid);
 #if defined(CONFIG_X86_LOCAL_APIC) && defined(CONFIG_X86_32)
 DECLARE_EARLY_PER_CPU(int, x86_cpu_to_logical_apicid);
-- 
1.7.7.6

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