[cfe-dev] Precompiled headers with libclang

[James K. Lowden]

On Fri, 6 Apr 2012 18:43:32 +0200
Matthieu Monrocq <matthieu.monrocq at gmail.com> wrote:
> Le 6 avril 2012 00:49, James K. Lowden <jklowden at schemamania.org> a
> écrit :
> > >
> > > Yes I am using FUSE filesystems.
> >
> > I'm having trouble imagining a why a
> > developer interested in speed would choose to keep source code (or
> > object code) on anything except locally attached storage.  
> 
> Editing code on a local PC but building and executing it on a server
> farm (because it's much faster) is a common pattern I think.

Granted, yes.  

> Then you have the choice of either keeping two copies of the code (one
> local, one on the server) and then synchronizing before
> compiling/running or to have them share their storage, one way or
> another.

Sure.  And your experience (and mine) both point to optimizing for
compilation.  

Because the number of files compiled will always equal or exceed the
number edited, and because I/O is a bigger fraction of the compiler's
performance than of the editor's (especially if we include the
keyboard), best results will come from the compiler using local
storage.  

You can edit over NFS or FUSE; you can use rsync; you can check in and
have the build script check out.  ISTM any of those would be faster
than encumbering the compiler I/O.  

Thanks for the explanation.  I see your motivation; I'm sure that even
if there are "better" ways, the particular environment you're in may
not be changed all that easily.  That said, optimizing away stat(2)
calls would be a limited victory at best.  The only way to make
compilation fast, in the end, is to arrange things such that it *can*
be fast.  

--jkl