x86, percpu: Collect hot percpu variables into one cacheline

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On x86_64, percpu variables current_task and kernel_stack are used for
get_current() and current_thread_info() respectively and thus are
often used close to each other.  Move definition of current_task to
kernel/cpu/common.c right above kernel_stack definition and align it
to cacheline so that they always fall into the same cacheline.  Two
percpu variables defined there together - irq_stack_ptr and irq_count
- are also pretty hot and will benefit from sharing the cacheline.

For consistency, current_task definition for x86_32 is also moved to
kernel/cpu/common.c.

Putting current_task and kernel_stack into the same cacheline was
suggested by Linus Torvalds.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

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This commit is contained in:

Tejun Heo 2009-08-03 14:12:19 +09:00

parent 3e352aa8ee

commit bdf977b374

3 changed files with 13 additions and 8 deletions

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15

arch/x86/kernel/cpu/common.c

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3

arch/x86/kernel/process_32.c

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3

arch/x86/kernel/process_64.c

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