Messages in this thread | | | From | Vincent Guittot <> | Date | Thu, 7 Jan 2021 09:27:04 +0100 | Subject | Re: [PATCH 1/1] sched/fair:Avoid unnecessary assignment to cfs_rq->on_list |
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On Thu, 7 Jan 2021 at 02:57, <qianjun.kernel@gmail.com> wrote: > > From: jun qian <qianjun.kernel@gmail.com> > > Obviously, cfs_rq->on_list is already equal to 1 when cfs_rq->on_list > is assigned a value of 1, so an else branch is needed to avoid unnecessary > assignment operations. > > Signed-off-by: jun qian <qianjun.kernel@gmail.com> > --- > kernel/sched/fair.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 04a3ce20da67..ef6ebd95443d 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -305,8 +305,8 @@ static inline bool list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) > > if (cfs_rq->on_list) > return rq->tmp_alone_branch == &rq->leaf_cfs_rq_list;
if cfs_rq->on_list == 1, list_add_leaf_cfs_rq() returns and will not unnecessary set cfs_rq->on_list
so your change is useless but makes the code less readable
> - > - cfs_rq->on_list = 1; > + else > + cfs_rq->on_list = 1; > > /* > * Ensure we either appear before our parent (if already > -- > 2.18.2 >
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