powerpc/mm: enable page parallel initialisation

Parallel initialisation has been enabled for X86, boot time is improved
greatly.  On Power8, it is improved greatly for small memory.  Here is
the result from my test on Power8 platform:

For 4GB of memory, boot time is improved by 59%, from 24.5s to 10s.

For 50GB memory, boot time is improved by 22%, from 56.8s to 43.8s.

Signed-off-by: Li Zhang <zhlcindy@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 832cc46..a030e5e 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -158,6 +158,7 @@ config PPC
        select ARCH_HAS_DEVMEM_IS_ALLOWED
        select HAVE_ARCH_SECCOMP_FILTER
        select ARCH_HAS_UBSAN_SANITIZE_ALL
+       select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
 
 config GENERIC_CSUM
        def_bool CPU_LITTLE_ENDIAN