On Thu, Apr 07, 2022 at 10:10:21AM -0700, Andres Freund wrote:
> Hi,
>
> On 2022-04-06 11:03:37 -0400, Andrew Dunstan wrote:
> > On 3/30/22 20:26, Andres Freund wrote:
> > > Could you try using dash to invoke configure here, and whether it makes
> > > configure faster?
> > I got weird failures re libxml/parser.h when I tried with dash. See
> > <https://cirrus-ci.com/task/5963254039052288> (It would be nice if we
> > could see config.log on failure.)
>
> Since dash won't help us to get the build time down sufficiently, and the
> tests don't pass without a separate build tree, I looked at what makes
> config/prep_buildtree so slow.
>
> It's largely just bad code. The slowest part are spawning one expr and mkdir
> -p for each directory. One 'cmp' for each makefile doesn't help either.
>
> The expr can be replaced with
> subdir=${item#$sourcetree}
> that's afaics posix syntax ([1]), not bash.
>
> Spawning one mkdir for each directory can be replaced by a single mkdir
> invocation with all the directories. On my linux workstation that gets the
> time for the first loop down from 1005ms to 38ms, really.
Even better?
(cd "$sourcetree" && find . -print |grep -E '/Makefile$|/GNUmakefile$' |grep -v
"$sourcetree/doc/src/sgml/images/" |xargs tar c) |
(cd "$buildtree" && tar x)
