On 23. 5. 8. 16:42, Christophe JAILLET wrote:
> Group some variables based on their sizes to reduce holes.
> On x86_64, this shrinks the size of 'struct devfreq_dev_status' from 72 to
> 64 bytes.
>
> This structure is used both to allocate static variables or is embedded in
> some other structures. In both cases, reducing its size is nice to have.
>
> Moreover, the whole structure now fits in a single cache line on x86_64.
>
> Finally, it makes the order of code match the order of the above kernel
> doc.
>
> Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> ---
> Using pahole
>
> Before:
> ======
> struct devfreq_dev_profile {
> long unsigned int initial_freq; /* 0 8 */
> unsigned int polling_ms; /* 8 4 */
> enum devfreq_timer timer; /* 12 4 */
> bool is_cooling_device; /* 16 1 */
>
> /* XXX 7 bytes hole, try to pack */
>
> int (*target)(struct device *, long unsigned int *, u32); /* 24 8 */
> int (*get_dev_status)(struct device *, struct devfreq_dev_status *); /* 32 8 */
> int (*get_cur_freq)(struct device *, long unsigned int *); /* 40 8 */
> void (*exit)(struct device *); /* 48 8 */
> long unsigned int * freq_table; /* 56 8 */
> /* --- cacheline 1 boundary (64 bytes) --- */
> unsigned int max_state; /* 64 4 */
>
> /* size: 72, cachelines: 2, members: 10 */
> /* sum members: 61, holes: 1, sum holes: 7 */
> /* padding: 4 */
> /* last cacheline: 8 bytes */
> };
>
>
> After:
> =====
> struct devfreq_dev_profile {
> long unsigned int initial_freq; /* 0 8 */
> unsigned int polling_ms; /* 8 4 */
> enum devfreq_timer timer; /* 12 4 */
> int (*target)(struct device *, long unsigned int *, u32); /* 16 8 */
> int (*get_dev_status)(struct device *, struct devfreq_dev_status *); /* 24 8 */
> int (*get_cur_freq)(struct device *, long unsigned int *); /* 32 8 */
> void (*exit)(struct device *); /* 40 8 */
> long unsigned int * freq_table; /* 48 8 */
> unsigned int max_state; /* 56 4 */
> bool is_cooling_device; /* 60 1 */
>
> /* size: 64, cachelines: 1, members: 10 */
> /* padding: 3 */
> };
> ---
> include/linux/devfreq.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 7fd704bb8f3d..d312ffbac4dd 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -108,7 +108,6 @@ struct devfreq_dev_profile {
> unsigned long initial_freq;
> unsigned int polling_ms;
> enum devfreq_timer timer;
> - bool is_cooling_device;
>
> int (*target)(struct device *dev, unsigned long *freq, u32 flags);
> int (*get_dev_status)(struct device *dev,
> @@ -118,6 +117,8 @@ struct devfreq_dev_profile {
>
> unsigned long *freq_table;
> unsigned int max_state;
> +
> + bool is_cooling_device;
> };
>
> /**
Applied it.
Thanks.
--
Best Regards,
Samsung Electronics
Chanwoo Choi
