The "dev->mvcount % wmax" thing was showing high in profiles (we do it
for each line which ~ 500 per frame)
│ 000010c0 <vivi_fillbuff>:
...
0,39 │ 70:┌─→mov 0x3ff4(%edi),%esi
0,22 │ 76:│ mov 0x2a0(%edi),%eax
0,30 │ │ mov -0x84(%ebp),%ebx
0,35 │ │ mov %eax,%edx
0,04 │ │ mov -0x7c(%ebp),%ecx
0,35 │ │ sar $0x1f,%edx
0,44 │ │ idivl -0x7c(%ebp)
21,68 │ │ imul %esi,%ecx
0,70 │ │ imul %esi,%ebx
0,52 │ │ add -0x88(%ebp),%ebx
1,65 │ │ mov %ebx,%eax
0,22 │ │ imul %edx,%esi
0,04 │ │ lea 0x3f4(%edi,%esi,1),%edx
2,18 │ │→ call vivi_fillbuff+0xa6
0,74 │ │ addl $0x1,-0x80(%ebp)
62,69 │ │ mov -0x7c(%ebp),%edx
1,18 │ │ mov -0x80(%ebp),%ecx
0,35 │ │ add %edx,-0x84(%ebp)
0,61 │ │ cmp %ecx,-0x8c(%ebp)
0,22 │ └──jne 70
so since all variables stay the same for all iterations let's move
computations out of the loop: the abovementioned division and
"width*pixelsize" too
before:
# 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
after:
# cmdline : /home/kirr/local/perf/bin/perf record -g -a sleep 20
#
# Samples: 46K of event 'cycles'
# Event count (approx.): 15574200568
#
# Overhead Command Shared Object
# ........ ............... ....................
#
27.99% rawv libc-2.13.so [.] __memcpy_ssse3
23.29% vivi-* [kernel.kallsyms] [k] memcpy
10.30% Xorg [unknown] [.] 0xa75c98f8
5.34% vivi-* [vivi] [k] gen_text.constprop.6
4.61% rawv [vivi] [k] gen_twopix
2.64% rawv [vivi] [k] precalculate_line
1.37% swapper [kernel.kallsyms] [k] read_hpet
0.79% Xorg [kernel.kallsyms] [k] read_hpet
0.64% Xorg [kernel.kallsyms] [k] unix_poll
0.45% Xorg [kernel.kallsyms] [k] fget_light
0.43% rawv libxcb.so.1.1.0 [.] 0x0000aae9
0.40% runsv [kernel.kallsyms] [k] ext2_try_to_allocate
0.36% Xorg [kernel.kallsyms] [k] _raw_spin_lock_irqsave
0.31% vivi-* [vivi] [k] vivi_fillbuff
(i.e. vivi_fillbuff own overhead is almost gone)
Signed-off-by: Kirill Smelkov <kirr@xxxxxxxxxx>
---
drivers/media/platform/vivi.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/media/platform/vivi.c b/drivers/media/platform/vivi.c
index ddcc712..0272d07 100644
--- a/drivers/media/platform/vivi.c
+++ b/drivers/media/platform/vivi.c
@@ -579,22 +579,23 @@ static void gen_text(struct vivi_dev *dev, char *basep,
static void vivi_fillbuff(struct vivi_dev *dev, struct vivi_buffer *buf)
{
- int wmax = dev->width;
+ int stride = dev->width * dev->pixelsize;
int hmax = dev->height;
struct timeval ts;
void *vbuf = vb2_plane_vaddr(&buf->vb, 0);
unsigned ms;
char str[100];
int h, line = 1;
+ u8 *linestart;
s32 gain;
if (!vbuf)
return;
+ linestart = dev->line + (dev->mv_count % dev->width) * dev->pixelsize;
+
for (h = 0; h < hmax; h++)
- memcpy(vbuf + h * wmax * dev->pixelsize,
- dev->line + (dev->mv_count % wmax) * dev->pixelsize,
- wmax * dev->pixelsize);
+ memcpy(vbuf + h * stride, linestart, stride);
/* Updates stream time */
--
1.8.0.316.g291341c
--
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