Very slow start

[Ole Tange]

$ make --version
GNU Make version 3.79.1, by Richard Stallman and Roland McGrath.
Built for i586-mandrake-linux-gnu
Copyright (C) 1988, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 2000
        Free Software Foundation, Inc.
This is free software; see the source for copying conditions.
There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

Report bugs to <address@hidden>.

I would like to use make's job scheduleing facility for running a bunch of
similar jobs in parallel, but never more than 10 simultationsly.

So I generated a Makefile like:

all : job1 job2 job3 job4 [...] job100000
.PHONY : job1
job1 :
        do_stuff xyzzy
.PHONY : job2
job2 :
        do_stuff fubar
.PHONY : job3
job3 :
        do_stuff foo
[...]
.PHONY : job100000
job100000 :
        do_stuff bar

For 10000 jobs it takes 10 cpu seconds (5 G clock cycles) before starting
job1. But with 100000 jobs make uses 15 cpu minutes (500 G clock cycles).

I agree that the dependency graph is quite large, but it is not at all
complex, so I would guess it has something to do with a datastructure that
is inefficient for large number of dependencies.


/Ole