Date: Sun, 11 Jun 2017 19:06:07 +0000 (UTC) From: Jilles Tjoelker <jilles@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r319828 - head/etc Message-ID: <201706111906.v5BJ676e039387@repo.freebsd.org>
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Author: jilles Date: Sun Jun 11 19:06:07 2017 New Revision: 319828 URL: https://svnweb.freebsd.org/changeset/base/319828 Log: 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) Modified: head/etc/rc.subr Modified: head/etc/rc.subr ============================================================================== --- head/etc/rc.subr Sun Jun 11 19:05:45 2017 (r319827) +++ head/etc/rc.subr Sun Jun 11 19:06:07 2017 (r319828) @@ -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=:
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