x86: Speed up ___preempt_schedule*() by using THUNK helpers

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___preempt_schedule() does SAVE_ALL/RESTORE_ALL but this is
suboptimal, we do not need to save/restore the callee-saved
register. And we already have arch/x86/lib/thunk_*.S which
implements the similar asm wrappers, so it makes sense to
redefine ___preempt_schedule() as "THUNK ..." and remove
preempt.S altogether.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921184153.GA23727@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

...

This commit is contained in:

Oleg Nesterov 2014-09-21 20:41:53 +02:00 • committed by Ingo Molnar

parent f3670394c2

commit 0ad6e3c519

4 changed files with 23 additions and 31 deletions

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2

arch/x86/kernel/Makefile

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25

arch/x86/kernel/preempt.S

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20

arch/x86/lib/thunk_32.S

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7

arch/x86/lib/thunk_64.S

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