From: Alexey Dobriyan <adobriyan@xxxxxxxxx> Subject: mm: shuffle GFP_* flags GFP_KERNEL is one of the most used constant but on archs like arm with fixed length instruction some constants are more equal than the others. Constants with tightly packed bits can be injected directly into instruction stream: 0: e3a00d33 mov r0, #3264 ; 0xcc0 Others require multiple instructions or even loading out of instruction stream: 0: e3a000c0 mov r0, #192 ; 0xc0 4: e3400060 movt r0, #96 ; 0x60 Shuffle GFP_* flags so that GFP_KERNEL/GFP_ATOMIC + __GFP_ZERO bits are close to each other. Savings on arm configs are ~0.1%. Link: http://lkml.kernel.org/r/20190109201838.GA9140@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/gfp.h | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) --- a/include/linux/gfp.h~mm-shuffle-gfp_-flags +++ a/include/linux/gfp.h @@ -24,21 +24,21 @@ struct vm_area_struct; #define ___GFP_HIGH 0x20u #define ___GFP_IO 0x40u #define ___GFP_FS 0x80u -#define ___GFP_WRITE 0x100u -#define ___GFP_NOWARN 0x200u -#define ___GFP_RETRY_MAYFAIL 0x400u -#define ___GFP_NOFAIL 0x800u -#define ___GFP_NORETRY 0x1000u -#define ___GFP_MEMALLOC 0x2000u -#define ___GFP_COMP 0x4000u -#define ___GFP_ZERO 0x8000u -#define ___GFP_NOMEMALLOC 0x10000u -#define ___GFP_HARDWALL 0x20000u -#define ___GFP_THISNODE 0x40000u -#define ___GFP_ATOMIC 0x80000u -#define ___GFP_ACCOUNT 0x100000u -#define ___GFP_DIRECT_RECLAIM 0x200000u -#define ___GFP_KSWAPD_RECLAIM 0x400000u +#define ___GFP_ZERO 0x100u +#define ___GFP_ATOMIC 0x200u +#define ___GFP_DIRECT_RECLAIM 0x400u +#define ___GFP_KSWAPD_RECLAIM 0x800u +#define ___GFP_WRITE 0x1000u +#define ___GFP_NOWARN 0x2000u +#define ___GFP_RETRY_MAYFAIL 0x4000u +#define ___GFP_NOFAIL 0x8000u +#define ___GFP_NORETRY 0x10000u +#define ___GFP_MEMALLOC 0x20000u +#define ___GFP_COMP 0x40000u +#define ___GFP_NOMEMALLOC 0x80000u +#define ___GFP_HARDWALL 0x100000u +#define ___GFP_THISNODE 0x200000u +#define ___GFP_ACCOUNT 0x400000u #ifdef CONFIG_LOCKDEP #define ___GFP_NOLOCKDEP 0x800000u #else _
