powerpc: create giveup_all()
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>
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 9414dcb..8f85678 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -26,6 +26,7 @@
extern void giveup_vsx(struct task_struct *);
extern void enable_kernel_spe(void);
extern void load_up_spe(struct task_struct *);
+extern void giveup_all(struct task_struct *);
extern void switch_booke_debug_regs(struct debug_reg *new_debug);
#ifdef CONFIG_PPC_FPU