Re: CHECK_STRUCTS/dmpstruct.h mechanism is broken.

[Alan Mackenzie <acm@muc.de>]

Hello, Noam.

On Fri, Apr 12, 2019 at 09:58:17 -0400, Noam Postavsky wrote:
> On Fri, 12 Apr 2019 at 09:37, Alan Mackenzie <acm@muc.de> wrote:

> > > I just now timed it, and './configure' took 29 real-time seconds
> > > whereas 'cd lisp; make -j16 compile-always' took 38 real-time
> > > seconds; this was with two circa-2013 Xeon E5-2640 v2 CPUs with 8
> > > cores each.  So on a 32-core platform, I expect ./configure to
> > > take longer than byte-compiling all the Lisp files - i.e.,
> > > 'configure' is ridiculously slow.

> > For the record, the slowness of `configure' irritates me, too.

> For the record, I use the --cache-file option, and `configure' runs in
> 2 real-time seconds. I use separate cache files per configuration, it
> works pretty well.

I tried that out yesterday, and indeed it takes about 2 seconds.  :-)

But it's not clear how ./configure -C works.  What gets cached, and how
does configure know when something needs determining again rather than
just copying a result from the cache?  Presumably one needs to be
prepared to delete the cache file when moving the top level directory to
a different environment, and things like that.

Is ./configure -C documented at all?

-- 
Alan Mackenzie (Nuremberg, Germany).