On 03/12/2011 15:08, Jilles Tjoelker wrote:
On Sat, Mar 12, 2011 at 09:13:08PM +0000, Doug Barton wrote:
Author: dougb
Date: Sat Mar 12 21:13:08 2011
New Revision: 219578
URL: http://svn.freebsd.org/changeset/base/219578
Log:
Use the allexport option in load_rc_config() in order to avoid having
to repeatedly read the conf files. Depending on what is enabled the
files are being read anywhere from 15, 30, or more times currently.
By loading the values in the environment this is reduced to 1, with
perhaps a couple more, again depending on what is enabled.
I wonder if it is a good idea to pollute the environment of many daemons
with this. Although sshd and cron clean it up, there is at least one
daemon that passes the environment on. One of those is devd.
I think the argument could be made that this is bad behavior on their
part, but if it turns out that it starts affecting things negatively we
can take another look at it.
While that
saves four /etc/rc.conf reads on my minimalistic 9-current VM, it
implies that devd must be restarted to pick up changes to /etc/rc.conf.
That seems a POLA violation.
I'm not sure what you mean by this. We've always required services to be
restarted to pick up rc.conf changes.
With the old code, my VM reads rc.conf nine times at boot. One of them
is the initial load, four of them are via devd and the other four are
because rc.d scripts call each other via execve(2) instead of via the
run_rc_script function.
The run_rc_script issue is one that should be looked at regardless,
you're right. The four that come out of devd are likely instances of
things being started via /etc/rc.d in devd.conf.
The latter four can be avoided but the other
five seem unavoidable.
I found this by adding the following line to /etc/rc.conf:
echo "rc.conf is being read at $(date) by $(ps -p $$ -o pid= -o ppid= -o
args=)">/dev/console
Yeah, I put something similar in rc.subr, so I think our results are
likely equivalent.
(The new code reads rc.conf once.)
The speed-up for boot and shutdown is negligible when rc.conf is
on local disk, noticable when accessing files over NFS, and dramatic
when pulling rc.conf values from a database.
This change also includes a minor optimization to the conditional
for $_rc_conf_loaded.
I don't know if we ever supported 'set -u' in rc.d scripts,
Not TMK, but I have no plans to MFC this right away, so I'm happy to
revisit it if it causes problems.
Thanks!
Doug
but this
definitely breaks it. To fix this, test "${_rc_conf_loaded-}" instead of
"$_rc_conf_loaded"
Modified:
head/etc/rc.subr
Modified: head/etc/rc.subr
==============================================================================
--- head/etc/rc.subr Sat Mar 12 20:36:52 2011 (r219577)
+++ head/etc/rc.subr Sat Mar 12 21:13:08 2011 (r219578)
@@ -998,9 +998,8 @@ load_rc_config()
err 3 'USAGE: load_rc_config name'
fi
- if ${_rc_conf_loaded:-false}; then
- :
- else
+ if [ -z "$_rc_conf_loaded" ]; then
+ set -o allexport
if [ -r /etc/defaults/rc.conf ]; then
debug "Sourcing /etc/defaults/rc.conf"
. /etc/defaults/rc.conf
@@ -1010,6 +1009,7 @@ load_rc_config()
. /etc/rc.conf
fi
_rc_conf_loaded=true
+ set +o allexport
fi
if [ -f /etc/rc.conf.d/"$_name" ]; then
debug "Sourcing /etc/rc.conf.d/${_name}"
--
Nothin' ever doesn't change, but nothin' changes much.
-- OK Go
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