powerpc: create giveup_all()

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Create a single function that gives everything up (FP, VMX, VSX, SPE).
Doing this all at once means we only do one MSR write.

A context switch microbenchmark using yield():

http://ozlabs.org/~anton/junkcode/context_switch2.c

./context_switch2 --test=yield --fp --altivec --vector 0 0

shows an improvement of 3% on POWER8.

Signed-off-by: Anton Blanchard <anton@samba.org>
[mpe: giveup_all() needs to be EXPORT_SYMBOL'ed]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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Anton Blanchard 2015-10-29 11:44:08 +11:00 • committed by Michael Ellerman

parent 1f2e25b2d5

commit c208505900

3 changed files with 64 additions and 30 deletions

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1

arch/powerpc/include/asm/switch_to.h

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76

arch/powerpc/kernel/process.c

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17

arch/powerpc/kvm/book3s_pr.c

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