[MPlayer-dev-eng] speed of link strategies

[Diego Biurrun]

On Thu, Jun 19, 2008 at 01:46:37PM +0200, Michael Niedermayer wrote:
> On Thu, Jun 19, 2008 at 11:29:34AM +0200, Diego Biurrun wrote:
> > Given that there are a total of 25 subdirectories to link, total link
> > times should have diminished with the new system when running a complete
> > build from a cold cache.
> 
> I dont really care if a full build takes 36m41s or 36m25s. I do care if
> each rebuild after testing takes 13.8s instead of 5.2s

Your example was compiling multiple times.  The disk cache will kick in
this case and the new system will link just as quickly.  It's not
important if a single link takes 8s longer every once in a while.
That's not a drain on anybody's time.

> > The conclusion seems to be clear: Total link times have been reduced by
> > the flat build system.  Rebuild link times are within 1s of the old
> > system on a very outdated machine.  
> 
> very outdated machine with RAID array ...

It's the only x86 machine I can run benchmarks on.

> > Adding complexity to the build
> > system to make up for that 1s is not worth any trouble.
> 
> Maybe not, but making up for that 50% speedloss might be. But then goals
> change, features and performance may not be amongth them anymore.

The principle goal is correctness, the secondary goal is simplicity,
performance comes third.

Correctness may not be sacrificed for speed or simplicity, ever.
Simplicity can be exchanged for performance if the tradeoff is
acceptable.

Per-directory linking is not a useful feature within MPlayer, it is a
pure speed hack.  The performance benefit is very doubtful and it would
come at the expense of considerable complication.  Thus I'm opposed to
it.

Diego

P.S.: Has anybody tried Gold, the new GNU ELF linker?  It is said to be
considerably faster...