[media] vivi: Move computations out of vivi_fillbuf linecopy loop
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@mns.spb.ru>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
13908f330f