[FFmpeg-devel] [PATCH 1/3] configure: speedup x2-x8

avih avihpit at yahoo.com
Sat Aug 25 21:08:55 EEST 2018


For overview see:
http://ffmpeg.org/pipermail/ffmpeg-devel/2018-August/233665.html

Attached is patch 1/3 which was at "main.patch" of that message.

About 50-70% of configure runtime was being spent inside one
function: flatten_extralibs() and callees resolve() and unique().
It manipulates strings and invoked nearly 20K (20000) subshells.
It was rewritten to avoid subshells, and ended up x50-x250 faster.

unique() now outputs a different order:
it was keeping the last instance of recurring items, now it
keeps the first. It affects libs order at ffbuild/config.{mak,sh} -
but I don't think it matters. If it does, "opt1-reorder-unique.patch"
restores the original order. Let me know if/why it matters and I'll
squash it and update the commit message accordingly if required.
 

    On Saturday, August 25, 2018 7:55 PM, Timo Rothenpieler <timo at rothenpieler.org> wrote:
 

 Please use git send-email to send your patches, or at least send each 
patch, created by git format-patch, as individual attachment. Your files 
seem to contain multiple patches one after another, which makes them 
very hard to follow.

But nice work! Let's hope this does not cause any regressions.
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