Messages in this thread | | | Subject | Re: [PATCH] sched/topology: One function call less in build_group_from_child_sched_domain() | From | "Enrico Weigelt, metux IT consult" <> | Date | Mon, 8 Jul 2019 11:38:58 +0200 |
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On 06.07.19 19:22, Srikar Dronamraju wrote: > * Markus Elfring <Markus.Elfring@web.de> [2019-07-06 16:05:17]: > >> From: Markus Elfring <elfring@users.sourceforge.net> >> Date: Sat, 6 Jul 2019 16:00:13 +0200 >> >> Avoid an extra function call by using a ternary operator instead of >> a conditional statement. >> >> This issue was detected by using the Coccinelle software. >> >> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net> >> --- >> kernel/sched/topology.c | 6 +----- >> 1 file changed, 1 insertion(+), 5 deletions(-) >> >> diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c >> index f751ce0b783e..6190eb52c30a 100644 >> --- a/kernel/sched/topology.c >> +++ b/kernel/sched/topology.c >> @@ -886,11 +886,7 @@ build_group_from_child_sched_domain(struct sched_domain *sd, int cpu) >> return NULL; >> >> sg_span = sched_group_span(sg); >> - if (sd->child) >> - cpumask_copy(sg_span, sched_domain_span(sd->child)); >> - else >> - cpumask_copy(sg_span, sched_domain_span(sd)); >> - >> + cpumask_copy(sg_span, sched_domain_span(sd->child ? sd->child : sd)); > > At runtime, Are we avoiding a function call? > However I think we are avoiding a branch instead of a conditional, which may > be beneficial.
If you're assuming the compiler doesn't already optimize that (no idea whether gcc really does that).
@Markus: could you check what gcc is actually generating out of both the old and your new version ?
--mtx
-- Enrico Weigelt, metux IT consult Free software and Linux embedded engineering info@metux.net -- +49-151-27565287
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