[FFmpeg-devel] [PATCH] lavc/aacenc_utils: unroll abs_pow34_v loop

[Reimar Döffinger]

On Tue, Mar 22, 2016 at 11:14:49AM -0700, Ganesh Ajjanagadde wrote:
> > Are you sure that this speedup (and the other patch you posted) is real and
> > above the error? Did you do multiple runs to rule out that it was chance?
> > 0.04/0.05 second improvement on 5 seconds doesn't seem significant at all,
> 
> I am really sorry about these measurements, they were screwed up by a
> very recent regression on my laptop due to some package upgrade.
> Essentially, put it to suspend, restore, and the clock freq/cpu
> governor would downshift slightly, from 2.4 to 2.2 GHz base, no idea
> about the changes to the turbo freq.

To benchmark really properly it is best to force the CPU to
a fixed frequency.
Otherwise you might end up benchmarking your CPU frequency governor
instead of your code.
It usually works fine without, but if the difference gets below
1% it generally becomes a must to do so.