Re: [PATCH v2 02/11] media: vsp1: Remove packed attributes from aligned structures

[Geert Uytterhoeven]

On Tue, Mar 13, 2018 at 7:05 PM, Kieran Bingham
 wrote:
> The use of the packed attribute can cause a performance penalty for
> all accesses to the struct members, as the compiler will assume that the
> structure has the potential to have an unaligned base.
>
> These structures are all correctly aligned and contain no holes, thus
> the attribute is redundant and negatively impacts performance, so we
> remove the attributes entirely.
>
> Signed-off-by: Kieran Bingham 

Reviewed-by: Geert Uytterhoeven 

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- ge...@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

[PATCH v2 02/11] media: vsp1: Remove packed attributes from aligned structures

[Kieran Bingham]

The use of the packed attribute can cause a performance penalty for
all accesses to the struct members, as the compiler will assume that the
structure has the potential to have an unaligned base.

These structures are all correctly aligned and contain no holes, thus
the attribute is redundant and negatively impacts performance, so we
remove the attributes entirely.

Signed-off-by: Kieran Bingham 
---
v2
 - Remove attributes entirely

 drivers/media/platform/vsp1/vsp1_dl.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/vsp1/vsp1_dl.c 
b/drivers/media/platform/vsp1/vsp1_dl.c
index 37e2c984fbf3..85795b55a357 100644
--- a/drivers/media/platform/vsp1/vsp1_dl.c
+++ b/drivers/media/platform/vsp1/vsp1_dl.c
@@ -29,19 +29,19 @@
 struct vsp1_dl_header_list {
u32 num_bytes;
u32 addr;
-} __attribute__((__packed__));
+};
 
 struct vsp1_dl_header {
u32 num_lists;
struct vsp1_dl_header_list lists[8];
u32 next_header;
u32 flags;
-} __attribute__((__packed__));
+};
 
 struct vsp1_dl_entry {
u32 addr;
u32 data;
-} __attribute__((__packed__));
+};
 
 /**
  * struct vsp1_dl_body - Display list body
-- 
git-series 0.9.1