I have been investigating some build performance issues, and trying to
narrow down causes of slowness, and observed an odd effect, which was
suggested by a huge time difference between building from git and
building from a tarball.
If I do
make -C src/port all
and then wait 10 seconds or so and do
make -j 3
or even just plain
make
the build finishes much much faster (like 1m vs 5m) than if I had not
run the first command.
I have seen this on a Fedora VM (VirtualBox, W7 host, Athlon II X2) and
a ScientificLinux 6 machine (dual quad xeon E5620).
The setup is a vpath build configured thus:
../pgsql/configure --enable-cassert --enable-debug --enable-integer-datetimes --with-perl --with-python --with-tcl
--with-krb5 --with-includes=/usr/include/et --with-openssl --with-ldap --with-libxml --with-libxslt
Can anyone with a bit more make-fu than I have suggest why this should
be so? Can we tweak the make files so hacks like this aren't required to
get a fast build? Can anyone replicate this odd result?
cheers
andrew