| Message ID | 483c58f72b5549ba5d8558ba4621c2489f231668.1351861552.git.kirr@mns.spb.ru (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/drivers/media/platform/vivi.c b/drivers/media/platform/vivi.c index cb2337e..ddcc712 100644 --- a/drivers/media/platform/vivi.c +++ b/drivers/media/platform/vivi.c @@ -242,7 +242,7 @@ 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;
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> --- drivers/media/platform/vivi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)