Re: [PATCH v2 2/2] x86: Added read_mostly declaration/definitionto vars from smp.h

From: Vlad
Date: Sun May 20 2012 - 09:56:06 EST


On 05/18/2012 11:14 AM, Ingo Molnar wrote:
* Vlad Zolotarov<vlad@xxxxxxxxxxx> wrote:

Added a "read-mostly" qualifier to the following variables in smp.h:
- cpu_sibling_map
- cpu_core_map
- cpu_llc_shared_map
- cpu_llc_id
- cpu_number
- x86_cpu_to_apicid
- x86_bios_cpu_apicid
- x86_cpu_to_logical_apicid

As long as all the variables above are only written during the initialization,
this change is meant to prevent the false sharing and improve the
performance on large multiprocessor systems.

Signed-off-by: Vlad Zolotarov<vlad@xxxxxxxxxxx>
Signed-off-by: Shai Fultheim<shai@xxxxxxxxxxx>
---
arch/x86/include/asm/apic.h | 2 +-
arch/x86/include/asm/smp.h | 16 ++++++++--------
arch/x86/kernel/apic/apic.c | 6 +++---
arch/x86/kernel/setup_percpu.c | 2 +-
arch/x86/kernel/smpboot.c | 8 ++++----
5 files changed, 17 insertions(+), 17 deletions(-)

This does not build on !SMP kernels that has APIC enabled.

Oops... :) My bad. I'll rebase and respin.

Thanks,
vlad


Thanks,

Ingo
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