From eaac4bffc7566a21e5e8429caa82d7d4249b9ff1 Mon Sep 17 00:00:00 2001 From: Jilles Tjoelker Date: Sun, 11 Jun 2017 19:06:07 +0000 Subject: [PATCH] rc.subr: Optimize repeated sourcing. When /etc/rc runs all /etc/rc.d scripts, it has already loaded /etc/rc.subr but each /etc/rc.d script sources it again (since /etc/rc.d scripts must also work when started stand-alone). Therefore, if rc.subr is already loaded, return so sh need not parse the rest of the file. A second effect is that there is no longer a compound command around most of rc.subr. This reduces memory usage while sh is loading rc.subr for the first time (but this memory is free()d once rc.subr is loaded). For purposes of porting this to other systems, I do not recommend porting this to systems with shells that do not have the change to the return special builtin like in r255215 (before FreeBSD 10.0-RELEASE). This change ensures that return in the top level of a dot script returns from the dot script, even if the dot script was sourced from a function. A comparison of CPU time on an amd64 bhyve virtual machine from a times command added near the end of /etc/rc, all four values summed: x orig1 + quickreturn +--------------------------------------------------------------------------+ | + + + x x x| ||______M__A_________| |______M___A__________| | +--------------------------------------------------------------------------+ N Min Max Median Avg Stddev x 3 1.704 1.802 1.726 1.744 0.051419841 + 3 1.467 1.559 1.487 1.5043333 0.048387326 Difference at 95.0% confidence -0.239667 +/- 0.113163 -13.7424% +/- 6.48873% (Student's t, pooled s = 0.0499266) --- etc/rc.subr | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) diff --git a/etc/rc.subr b/etc/rc.subr index fbbf5b082bb..3c66ee9deed 100644 --- a/etc/rc.subr +++ b/etc/rc.subr @@ -38,7 +38,9 @@ # Operating System dependent/independent variables # -if [ -z "${_rc_subr_loaded}" ]; then +if [ -n "${_rc_subr_loaded}" ]; then + return +fi _rc_subr_loaded="YES" @@ -2126,7 +2128,3 @@ _echoonce() if kenv -q rc.debug > /dev/null ; then rc_debug=YES fi - -fi # [ -z "${_rc_subr_loaded}" ] - -_rc_subr_loaded=: