Re: [PATCH 1/2] powerpc: Only disable HAVE_EFFICIENT_UNALIGNED_ACCESS on POWER7 little endian
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2016-09-25 22:45:22
On Sun, 2016-09-25 at 22:35 +1000, Anton Blanchard wrote:
From: Anton Blanchard <redacted>
POWER8 handles unaligned accesses in little endian mode, but commit
0b5e6661ac69 ("powerpc: Don't set HAVE_EFFICIENT_UNALIGNED_ACCESS on
little endian builds") disabled it for all.
The issue with unaligned little endian accesses is specific to
POWER7,
so update the Kconfig check to match. Using the stat() testcase from
commit a75c380c7129 ("powerpc: Enable DCACHE_WORD_ACCESS on
ppc64le"),
performance improves 15% on POWER8.Hrm.. this should really be a runtime switch...
quoted hunk ↗ jump to hunk
Signed-off-by: Anton Blanchard <redacted> --- arch/powerpc/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 0a70c86..04c447d 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig@@ -96,7 +96,7 @@ config PPCselect VIRT_TO_BUS if !PPC64 select HAVE_IDE select HAVE_IOREMAP_PROT - select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_LITTLE_ENDIAN + select HAVE_EFFICIENT_UNALIGNED_ACCESS if !(CPU_LITTLE_ENDIAN && POWER7_CPU) select HAVE_KPROBES select HAVE_ARCH_KGDB select HAVE_KRETPROBES