2.6.18-rc1 make -j4 does not run parallel

From: Keith Owens
Date: Sat Aug 12 2006 - 22:57:06 EST

Dual cpu system.
'echo $$' reports current id is 4972
export KBUILD_OUTPUT=../obj
make -j4

Building a tree, 'LANG= pstree -pl 4972' shows multiple tasks
running in parallel. Even here it is only running 2 instead of the 4
that I expect.

| `-cc1(8573)

build a 2.6.18-rc1 or later tree, make -j4 does not run parallel. All
pstree output shows a single branch, like this.


Using 'make -j' without a number or 'make -j<n>' where <n> is greater
than 4 does show parallel build behaviour. Looks like something is
decrementing -j<n> as you go down the make tree and decrementing it
enough that it ends up in a serial build.
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