[FFmpeg-devel] [PATCH] ppc: replace vec_ld(0), vec_ld(1) by VEC_LD2() which has fewer loads

Michael Niedermayer michaelni at gmx.at
Sun Nov 16 12:03:36 CET 2014

On Sat, Nov 15, 2014 at 07:28:25PM -0700, Pavel Koshevoy wrote:
> On 11/15/14 18:12, James Almer wrote:
> >On 15/11/14 1:50 AM, Michael Niedermayer wrote:
> >>On Fri, Nov 14, 2014 at 09:00:31PM -0700, Pavel Koshevoy wrote:
> >>>I ran both builds twice and captured the output from the second run
> >>>of each build, it's in the attachment.  By the looks of it there is
> >>>no difference in performance.
> >>to compare START/STOP_TIMER data its generally best to run the
> >>test a few times (like 3) and compare the values from each that
> >>have some specific number or runs, like
> >>
> >>>681 UNITS in MC, 4192359 runs, 1945 skips0:01:40.88 bitrate=N/A
> >>vs.
> >>>668 UNITS in MC, 4192326 runs, 1978 skips0:01:40.16 bitrate=N/A
> >>but from these 2 tests it seems you are correct and theres no
> >>significant difference so theres probably not much point in doing
> >>further tests
> >>
> >It might be a good idea to try -threads 1 for the input file as well
> >
> I've done 4 runs for each build using vec_ld and VEC_LD2, and logged
> the results of the last 3 runs for each build.
> The results are in the attachment.  This time I added -an -threads 1
> and the fps went up for both builds.  It seems VEC_LD2 is slightly
> faster.
> I am not sure I've put -threads 1 in the right place on the command
> line, and I don't know if it matters -- this is a single-core ppc
> G4.

> Let me know if you would like me to try something else.

no, thanks alot

it seems the conclusion is that its 1 cpu cycle faster for you and
slower for carl, thus overall its basically the same speed.


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

When the tyrant has disposed of foreign enemies by conquest or treaty, and
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some war or other, in order that the people may require a leader. -- Plato
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