diff options
| author | Anton Blanchard <anton@samba.org> | 2015-10-29 11:43:55 +1100 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2015-12-01 13:52:24 +1100 |
| commit | 152d523e6307c7152f9986a542f873b5c5863937 (patch) | |
| tree | de3b7ec6c667e368f922f2cc17bf7c1806ac28dd /arch/powerpc/include/asm/processor.h | |
| parent | af72ab646a6bee724f190820e8f56497a5b635f0 (diff) | |
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/processor.h')
| -rw-r--r-- | arch/powerpc/include/asm/processor.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h index 5afea361beaa..c273f3e0ba84 100644 --- a/arch/powerpc/include/asm/processor.h +++ b/arch/powerpc/include/asm/processor.h @@ -294,6 +294,7 @@ struct thread_struct { #endif #ifdef CONFIG_PPC64 unsigned long dscr; + unsigned long fscr; /* * This member element dscr_inherit indicates that the process * has explicitly attempted and changed the DSCR register value |