On Sat, 2015-03-07 at 19:14 +0800, Kevin Hao wrote:
> All the cache line size of the current book3e 64bit SoCs are 64 bytes.
> So we should use this size to align the member of paca_struct.
> With this change we save 192 bytes. Also change it to __aligned(size)
> since it is preferred over __attribute__((aligned(size))).
Why should we favor the book3e CPUs over the book3s ones ? Since we
can't build a kernel that deals with both, make it a compile option.
> Before:
> /* size: 1920, cachelines: 30, members: 46 */
> /* sum members: 1667, holes: 6, sum holes: 141 */
> /* padding: 112 */
>
> After:
> /* size: 1728, cachelines: 27, members: 46 */
> /* sum members: 1667, holes: 4, sum holes: 13 */
> /* padding: 48 */
>
> Signed-off-by: Kevin Hao <haoke...@gmail.com>
> ---
> arch/powerpc/include/asm/paca.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
> index e5f22c6c4bf9..70bd4381f8e6 100644
> --- a/arch/powerpc/include/asm/paca.h
> +++ b/arch/powerpc/include/asm/paca.h
> @@ -106,9 +106,9 @@ struct paca_struct {
> #endif /* CONFIG_PPC_STD_MMU_64 */
>
> #ifdef CONFIG_PPC_BOOK3E
> - u64 exgen[8] __attribute__((aligned(0x80)));
> + u64 exgen[8] __aligned(0x40);
> /* Keep pgd in the same cacheline as the start of extlb */
> - pgd_t *pgd __attribute__((aligned(0x80))); /* Current PGD */
> + pgd_t *pgd __aligned(0x40); /* Current PGD */
> pgd_t *kernel_pgd; /* Kernel PGD */
>
> /* Shared by all threads of a core -- points to tcd of first thread */
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