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authorKirill Smelkov <kirr@mns.spb.ru>2012-11-02 09:10:31 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2012-12-21 18:25:34 -0200
commit10ce84415836d3fbf907367b9eb595a0dfd6ccb1 (patch)
tree4226e06792927e1d9bc4d7fd43f483aa8f6cd566 /drivers/media/platform
parente3a8b4d22b47b3ee17baccdc5b351465f890671c (diff)
[media] vivi: vivi_dev->line[] was not aligned
Though dev->line[] is u8 array we work with it as with u16, u24 or u32 pixels, and also pass it to memcpy() and it's better to align it to at least 4. Before the patch, on x86 offsetof(vivi_dev, line) was 1003 and after patch it is 1004. There is slight performance increase, but I think is is slight, only because we start copying not from line[0]: ---- 8< ---- drivers/media/platform/vivi.c static void vivi_fillbuff(struct vivi_dev *dev, struct vivi_buffer *buf) { ... for (h = 0; h < hmax; h++) memcpy(vbuf + h * wmax * dev->pixelsize, dev->line + (dev->mv_count % wmax) * dev->pixelsize, wmax * dev->pixelsize); before: # cmdline : /home/kirr/local/perf/bin/perf record -g -a sleep 20 # # Samples: 49K of event 'cycles' # Event count (approx.): 16799780016 # # Overhead Command Shared Object # ........ ............... .................... # 27.51% rawv libc-2.13.so [.] __memcpy_ssse3 23.77% vivi-* [kernel.kallsyms] [k] memcpy 9.96% Xorg [unknown] [.] 0xa76f5e12 4.94% vivi-* [vivi] [k] gen_text.constprop.6 4.44% rawv [vivi] [k] gen_twopix 3.17% vivi-* [vivi] [k] vivi_fillbuff 2.45% rawv [vivi] [k] precalculate_line 1.20% swapper [kernel.kallsyms] [k] read_hpet 23.77% vivi-* [kernel.kallsyms] [k] memcpy | --- memcpy | |--99.28%-- vivi_fillbuff | vivi_thread | kthread | ret_from_kernel_thread --0.72%-- [...] after: # cmdline : /home/kirr/local/perf/bin/perf record -g -a sleep 20 # # Samples: 49K of event 'cycles' # Event count (approx.): 16475832370 # # Overhead Command Shared Object # ........ ............... ...................... # 29.07% rawv libc-2.13.so [.] __memcpy_ssse3 20.57% vivi-* [kernel.kallsyms] [k] memcpy 10.20% Xorg [unknown] [.] 0xa7301494 5.16% vivi-* [vivi] [k] gen_text.constprop.6 4.43% rawv [vivi] [k] gen_twopix 4.36% vivi-* [vivi] [k] vivi_fillbuff 2.42% rawv [vivi] [k] precalculate_line 1.33% swapper [kernel.kallsyms] [k] read_hpet Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru> Acked-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/platform')
-rw-r--r--drivers/media/platform/vivi.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/media/platform/vivi.c b/drivers/media/platform/vivi.c
index 3801a8d00946..a3090f0312c1 100644
--- a/drivers/media/platform/vivi.c
+++ b/drivers/media/platform/vivi.c
@@ -237,7 +237,7 @@ struct vivi_dev {
unsigned int field_count;
u8 bars[9][3];
- u8 line[MAX_WIDTH * 8];
+ u8 line[MAX_WIDTH * 8] __attribute__((__aligned__(4)));
unsigned int pixelsize;
u8 alpha_component;
u32 textfg, textbg;

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