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[media] vivi: Optimize precalculate_line() 

precalculate_line() is not very high on profile, but it calls expensive
gen_twopix(), so let's polish it too:
    call gen_twopix() only once for every color bar and then distribute
    the result.
before:
    # 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
after:
    # cmdline : /home/kirr/local/perf/bin/perf record -g -a sleep 20
    #
    # Samples: 45K of event 'cycles'
    # Event count (approx.): 15561769214
    #
    # Overhead          Command         Shared Object
    # ........  ...............  ....................
    #
        30.73%             rawv  libc-2.13.so          [.] __memcpy_ssse3
        26.78%           vivi-*  [kernel.kallsyms]     [k] memcpy
        10.68%             Xorg  [unknown]             [.] 0xa73015e9
         5.55%           vivi-*  [vivi]                [k] gen_text.constprop.6
         1.36%          swapper  [kernel.kallsyms]     [k] read_hpet
         0.96%             Xorg  [kernel.kallsyms]     [k] read_hpet
         ...
         0.16%             rawv  [vivi]                [k] precalculate_line
         ...
         0.14%             rawv  [vivi]                [k] gen_twopix
(i.e. gen_twopix and precalculate_line overheads are 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>
This commit is contained in:
Kirill Smelkov 2012-11-02 09:10:33 -03:00 committed by Mauro Carvalho Chehab
parent 13908f330f
commit d40fbf8d52
1 changed files with 14 additions and 4 deletions
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18
drivers/media/platform/vivi.c
View File

@ -512,12 +512,22 @@ static void gen_twopix(struct vivi_dev *dev, u8 *buf, int colorpos, bool odd)
static void precalculate_line(struct vivi_dev *dev)
{
int w;
unsigned pixsize = dev->pixelsize;
unsigned pixsize2 = 2*pixsize;
int colorpos;
u8 *pos;
for (w = 0; w < dev->width * 2; w++) {
int colorpos = w / (dev->width / 8) % 8;
for (colorpos = 0; colorpos < 16; ++colorpos) {
u8 pix[8];
int wstart = colorpos * dev->width / 8;
int wend = (colorpos+1) * dev->width / 8;
int w;
gen_twopix(dev, dev->line + w * dev->pixelsize, colorpos, w & 1);
gen_twopix(dev, &pix[0], colorpos % 8, 0);
gen_twopix(dev, &pix[pixsize], colorpos % 8, 1);
for (w = wstart/2*2, pos = dev->line + w*pixsize; w < wend; w += 2, pos += pixsize2)
memcpy(pos, pix, pixsize2);
}
}