Re: Speeding up config.status

[Akim Demaille]

>>>>> "Tom" == Tom Tromey <address@hidden> writes:

Sorry I sent the message by accident :(  It was not finished :(

Tom> Lately I've been thinking about speeding up config.status,
Tom> especially as regards automake.

I might be wrong, but I don't think today this is really needed: 2.50
has a much faster config.status.

* Fileutils 4.0, Autoconf 2.12, 19 AC_OUTPUT (5 k lines)
============================================

/tmp/fileutils-4.0 % time ./config.status                        nostromo 11:42
creating Makefile
creating doc/Makefile
creating intl/Makefile
creating lib/Makefile
creating man/Makefile
creating m4/Makefile
creating po/Makefile.in
creating src/Makefile
creating tests/Makefile
creating tests/cp/Makefile
creating tests/dircolors/Makefile
creating tests/install/Makefile
creating tests/ln/Makefile
creating tests/ls/Makefile
creating tests/ls-2/Makefile
creating tests/mkdir/Makefile
creating tests/mv/Makefile
creating tests/rm/Makefile
creating tests/touch/Makefile
creating config.h
config.h is unchanged
./config.status  2,33s user 0,57s system 11% cpu 26,028 total
/tmp/fileutils-4.0 % cat **/Makefile.in | wc -l                  nostromo 11:45
   5114


* Fileutils 4.1, Autoconf 2.49e, 25 AC_OUTPUT (9 k lines)
=============================================

/tmp/fileutils-4.1 % time ./config.status                        nostromo 11:43
config.status: creating Makefile
config.status: creating doc/Makefile
config.status: creating intl/Makefile
config.status: creating lib/Makefile
config.status: creating man/Makefile
config.status: creating m4/Makefile
config.status: creating po/Makefile.in
config.status: creating src/Makefile
config.status: creating tests/Makefile
config.status: creating tests/chgrp/Makefile
config.status: creating tests/chmod/Makefile
config.status: creating tests/cp/Makefile
config.status: creating tests/dd/Makefile
config.status: creating tests/du/Makefile
config.status: creating tests/dircolors/Makefile
config.status: creating tests/install/Makefile
config.status: creating tests/ln/Makefile
config.status: creating tests/ls/Makefile
config.status: creating tests/ls-2/Makefile
config.status: creating tests/mkdir/Makefile
config.status: creating tests/mv/Makefile
config.status: creating tests/rm/Makefile
config.status: creating tests/rmdir/Makefile
config.status: creating tests/shred/Makefile
config.status: creating tests/touch/Makefile
config.status: creating config.h
config.status: config.h is unchanged
./config.status  1,88s user 0,90s system 8% cpu 32,693 total
/tmp/fileutils-4.1 % cat **/Makefile.in|wc -l                    nostromo 11:44
   8967



Hm...  Well, yes, speeding this up would be pretty beneficial.  IMHO,
something which would help could be to have single file with only the
substitutions to perform, instead of the whole Makefile.in, which
contains a lot of lines where no substitution is to be performed.

Now that you have a portable include technology, this should be rather
easy.