Problems with make -j

[Benjamin Lutz]

Hello,

As a pet project I've started to change /etc/rc so it uses make(1) to 
execute the scripts in /etc/rc.d instead of executing them one after the 
other like the standard /etc/rc does. The goal of the project is to speed 
up boot time by executing rc.d scripts in parallel.

Now, if I don't specify a -j parameter this works just fine. I've written 
a script that generates a Makefile with all the rc.d dependencies in it, 
and using that the system boots just fine.

As soon as I add a -j parameter to make, even -j 1, things break though. 
Scripts (eg, rc.subr) are being spewed to the screen several times, and 
execution hangs at /etc/rc.d/adjkerntz (I think). I can pipe all this to 
a log file with > make.log 2>&1. By the time make gets to adjkerntz and I 
ctrl-c it, the logfile is slightly above 3MB.

Can anyone tell me why make behaves like this? If I had to guess I'd say 
something's happening to the file descriptors, or something that make 
needs for -j to work has not been set up. Btw, I have set up a memory 
disk in /etc/tmp that make can use for -j (and I've patched make to use 
that patch).

Here's what I use in /etc/rc now:

===== SNIPPET START =====
RC_MAKE="1"

if [ -z "$RC_MAKE" ]; then
        skip="-s nostart"
        [ `/sbin/sysctl -n security.jail.jailed` -eq 1 ] && \
                skip="$skip -s nojail"
        files=`rcorder ${skip} /etc/rc.d/* 2>/dev/null`

        for _rc_elem in ${files}; do
                run_rc_script ${_rc_elem} ${_boot}
        done
else
        skip="-DSKIP -DNOSTART"
        [ `/sbin/sysctl -n security.jail.jailed` -eq 1 ] && \
                skip="$skip -DNOJAIL"
        /sbin/mdmfs -M -S -o sync -s 5m md0 /etc/tmp
        /bin/rc_make -i -f /etc/Makefile ${skip} PARAM=${_boot}
        /sbin/umount /dev/md0
        /sbin/mdconfig -d -u md0
fi
===== SNIPPET END =====

Here's two example targets from the /etc/Makefile:

===== SNIPPET START =====
abi! LOGIN archdep
.ifdef !KEEP || NOJAIL
.ifdef !SKIP || (!NOJAIL)
        . /etc/rc.subr && run_rc_script /etc/rc.d/abi ${PARAM}
.endif
.endif

accounting! mountcritremote
.ifdef !KEEP || NOJAIL
.ifdef !SKIP || (!NOJAIL)
        . /etc/rc.subr && run_rc_script /etc/rc.d/accounting ${PARAM}
.endif
.endif
===== SNIPPET END =====

This currently works. As soon as I add "-j 1" or "-j 2" to the rc_make 
call above, I get the behaviour described above.

Note that rc_make is standard make(1) except that TMPPAT has been changed 
from /tmp to /etc/tmp.

Cheers
Benjamin
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