[mythtv] Android Release builds

[David Engel]

On Wed, Sep 19, 2018 at 11:07:51PM -0500, David Engel wrote:
> On Wed, Sep 19, 2018 at 02:46:07PM -0500, David Engel wrote:
> > On Wed, Sep 19, 2018 at 02:55:06PM -0400, Peter Bennett wrote:
> > > On 09/19/2018 11:05 AM, David Engel wrote:
> > > > Not coincidentally, I'd started building my own Android package with
> > > > --compile-type=profile on Sunday.  I later noticed that skips were
> > > > considerably longer on my Shield.  The video took around .5 to .8
> > > > seconds to resume instead of about .1 seconds like before.  In
> > > > addition, the audio started right away while the video was still
> > > > frozen.  It made for a jarring and unpleasant effect.
> > > > 
> > > > I hand't built an Android package in over a week so my first suspicion
> > > > was the new, vaapi2 changes were to blame.  After, several test
> > > > builds, I finally confirmed last that it wasn't the vaapi2 changes.
> > > > Rather, it was using compile type profile.  For as yet unknown
> > > > reasons, compile type profile produces worse code than compile type
> > > > debug on Android, at least when measuered by skip performance.
> > > I built using the release mythbuild.sh option, which now does compile type
> > > "profile". I find skips to still be instantaneous. Are you using a recording
> > > or a video? Does the recording have a seek table? Maybe the seek table
> > > actually slows it down? Personally I am suspicious of the seek table and
> > > would like to get rid of it.
> > 
> > The seek tables are fine and I always used the same recordings when
> > doing before and after comparisons.
> 
> This is partially but still not totally solved.
> 
> When I built with profile before, I simply changed
> CONFIGUREBUILDTYPE="debug --enable-small" to
> CONFIGUREBUILDTYPE="profile --enable-small".  With "profile
> --enable-small", skips were noticeably slower as I reported.
> 
> Tonight, I built with simply "profile".  With "profile", skips at 1x
> speed were comparable to "debug --enable-small" (good).  At higher
> 1.8x, however, skips were noticeably slower again (bad).
> 
> In short, dropping "--enable-small" helped but there is still an
> issue.  I'm going to try some other option combinations.

Plain "debug" (without "--enable-small") is fine as is building with
"release".  I had always thought that gcc's profiling support has
negligible overhead except when it is actually used with tools like
gperf.  These results seem to contradict that.

David
-- 
David Engel
david at istwok.net