powerpc: Enable DCACHE_WORD_ACCESS on ppc64le
Enable on DCACHE_WORD_ACCESS on ppc64le. It should work on
ppc64 and ppc32 but we need to do some testing first.
A somewhat reasonable testcase used to show the performance
improvement - a repeated stat of a 33 byte filename that
doesn't exist:
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#define ITERATIONS 10000000
#define PATH "123456781234567812345678123456781"
int main(void)
{
unsigned long i;
struct stat buf;
for (i = 0; i < ITERATIONS; i++)
stat(PATH, &buf);
return 0;
}
runs 27% faster on POWER8.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index ece1c01..56da472 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -147,6 +147,7 @@
select ARCH_USE_CMPXCHG_LOCKREF if PPC64
select HAVE_ARCH_AUDITSYSCALL
select ARCH_SUPPORTS_ATOMIC_RMW
+ select DCACHE_WORD_ACCESS if PPC64 && CPU_LITTLE_ENDIAN
config GENERIC_CSUM
def_bool CPU_LITTLE_ENDIAN