On Tue, 14 Feb 2023, Christophe JAILLET wrote:
> Group some variables based on their sizes to reduce hole and avoid padding.
> On x86_64, this shrinks the size from 144 to 128 bytes.
>
> As an example:
>
> $ size drivers/mfd/as3722.o (Before)
> text data bss dec hex filename
> 9441 680 16 10137 2799 drivers/mfd/as3722.o
>
> $ size drivers/mfd/as3722.o (After)
> text data bss dec hex filename
> 9345 680 16 10041 2739 drivers/mfd/as3722.o
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> ---
> Using pahole
>
> Before:
> ======
> struct mfd_cell {
> const char * name; /* 0 8 */
> int id; /* 8 4 */
> int level; /* 12 4 */
> int (*enable)(struct platform_device *); /* 16 8 */
> int (*disable)(struct platform_device *); /* 24 8 */
> int (*suspend)(struct platform_device *); /* 32 8 */
> int (*resume)(struct platform_device *); /* 40 8 */
> void * platform_data; /* 48 8 */
> size_t pdata_size; /* 56 8 */
> /* --- cacheline 1 boundary (64 bytes) --- */
> const struct software_node * swnode; /* 64 8 */
> const char * of_compatible; /* 72 8 */
> const u64 of_reg; /* 80 8 */
> bool use_of_reg; /* 88 1 */
>
> /* XXX 7 bytes hole, try to pack */
>
> const struct mfd_cell_acpi_match * acpi_match; /* 96 8 */
> int num_resources; /* 104 4 */
>
> /* XXX 4 bytes hole, try to pack */
>
> const struct resource * resources; /* 112 8 */
> bool ignore_resource_conflicts; /* 120 1 */
> bool pm_runtime_no_callbacks; /* 121 1 */
>
> /* XXX 6 bytes hole, try to pack */
>
> /* --- cacheline 2 boundary (128 bytes) --- */
> const char * const * parent_supplies; /* 128 8 */
> int num_parent_supplies; /* 136 4 */
>
> /* size: 144, cachelines: 3, members: 20 */
> /* sum members: 123, holes: 3, sum holes: 17 */
> /* padding: 4 */
> /* last cacheline: 16 bytes */
> };
>
>
> After:
> =====
> struct mfd_cell {
> const char * name; /* 0 8 */
> int id; /* 8 4 */
> int level; /* 12 4 */
> int (*enable)(struct platform_device *); /* 16 8 */
> int (*disable)(struct platform_device *); /* 24 8 */
> int (*suspend)(struct platform_device *); /* 32 8 */
> int (*resume)(struct platform_device *); /* 40 8 */
> void * platform_data; /* 48 8 */
> size_t pdata_size; /* 56 8 */
> /* --- cacheline 1 boundary (64 bytes) --- */
> const struct mfd_cell_acpi_match * acpi_match; /* 64 8 */
> const struct software_node * swnode; /* 72 8 */
> const char * of_compatible; /* 80 8 */
> const u64 of_reg; /* 88 8 */
> bool use_of_reg; /* 96 1 */
>
> /* XXX 3 bytes hole, try to pack */
>
> int num_resources; /* 100 4 */
> const struct resource * resources; /* 104 8 */
> bool ignore_resource_conflicts; /* 112 1 */
> bool pm_runtime_no_callbacks; /* 113 1 */
>
> /* XXX 2 bytes hole, try to pack */
>
> int num_parent_supplies; /* 116 4 */
> const char * const * parent_supplies; /* 120 8 */
>
> /* size: 128, cachelines: 2, members: 20 */
> /* sum members: 123, holes: 2, sum holes: 5 */
> };
> ---
> include/linux/mfd/core.h | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
Applied, thanks
--
Lee Jones [李琼斯]
