summaryrefslogtreecommitdiff
path: root/arch/powerpc/include/asm/switch_to.h
diff options
context:
space:
mode:
authorAnton Blanchard <anton@samba.org>2015-10-29 03:43:55 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2015-12-01 05:52:24 +0300
commit152d523e6307c7152f9986a542f873b5c5863937 (patch)
treede3b7ec6c667e368f922f2cc17bf7c1806ac28dd /arch/powerpc/include/asm/switch_to.h
parentaf72ab646a6bee724f190820e8f56497a5b635f0 (diff)
downloadlinux-152d523e6307c7152f9986a542f873b5c5863937.tar.xz
powerpc: Create context switch helpers save_sprs() and restore_sprs()
Move all our context switch SPR save and restore code into two helpers. We do a few optimisations: - Group all mfsprs and all mtsprs. In many cases an mtspr sets a scoreboarding bit that an mfspr waits on, so the current practise of mfspr A; mtspr A; mfpsr B; mtspr B is the worst scheduling we can do. - SPR writes are slow, so check that the value is changing before writing it. A context switch microbenchmark using yield(): http://ozlabs.org/~anton/junkcode/context_switch2.c ./context_switch2 --test=yield 0 0 shows an improvement of almost 10% on POWER8. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/asm/switch_to.h')
-rw-r--r--arch/powerpc/include/asm/switch_to.h11
1 files changed, 0 insertions, 11 deletions
diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index 15cca17cba4b..33a071d24ba8 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -15,17 +15,6 @@ extern struct task_struct *__switch_to(struct task_struct *,
struct thread_struct;
extern struct task_struct *_switch(struct thread_struct *prev,
struct thread_struct *next);
-#ifdef CONFIG_PPC_BOOK3S_64
-static inline void save_early_sprs(struct thread_struct *prev)
-{
- if (cpu_has_feature(CPU_FTR_ARCH_207S))
- prev->tar = mfspr(SPRN_TAR);
- if (cpu_has_feature(CPU_FTR_DSCR))
- prev->dscr = mfspr(SPRN_DSCR);
-}
-#else
-static inline void save_early_sprs(struct thread_struct *prev) {}
-#endif
extern void enable_kernel_fp(void);
extern void enable_kernel_altivec(void);