On 4/7/22 13:10, 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. > > That has the danger of the commandline getting too long. But since we rely on > the final link of the backend to be done in a single command, I don't think > it's making things worse? We could try to use xargs otherwise, iirc that's in > posix as well. > > Using parameter substitution in the second loop takes it down from 775ms to > 533ms. Not calling cmp when the file doesn't exist cuts it down to 337ms. > > I don't know of a way to batch the call to ln. The time with ln replaced with > : is 151ms, fwiw.
AFAIK Msy2s 'ln -s' by default copies a non-directory rather than actually symlinking it. If we want real symlinks, then we need MSYS=|winsymlinks:nativestrict set. The is will fail unless the calling user is an Administrator or has the SeCreateSymbolicLink privilege. See | |<https://postgr.es/m/|e05b213c-1257-84d4-f079-5c4d8c79e...@dunslane.net> for more details. > On windows that makes prep_buildtree go from 42.4s to 5.8s for me. That's pretty good. I think we can get rid of the CVS pruning, it's only 15 years or so since we've had that in the tree. + if test ! -d "$buildtree/$subdir"; then + echo "$buildtree/$subdir" + fi I would probably just write that as test -d "$buildtree/$subdir' || echo "$buildtree/$subdir" although it's really just a matter of taste. cheers andrew -- Andrew Dunstan EDB: https://www.enterprisedb.com
