lkml.org 
[lkml]   [2019]   [Dec]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] sched/fair: Optimize select_idle_core
* Vincent Guittot <vincent.guittot@linaro.org> [2019-12-05 18:27:51]:

> Hi Srikar,
>
> On Thu, 5 Dec 2019 at 18:23, Srikar Dronamraju
> <srikar@linux.vnet.ibm.com> wrote:
> >
> > Currently we loop through all threads of a core to evaluate if the core
> > is idle or not. This is unnecessary. If a thread of a core is not
> > idle, skip evaluating other threads of a core.
>
> I think that the goal is also to clear all CPUs of the core from the
> cpumask of the loop above so it will not try the same core next time
>
> >

That goal we still continue to maintain by the way of cpumask_andnot.
i.e instead of clearing CPUs one at a time, we clear all the CPUs in the
core at one shot.

> > Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> > ---
> > kernel/sched/fair.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 69a81a5709ff..b9d628128cfc 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -5872,10 +5872,12 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
> > bool idle = true;
> >
> > for_each_cpu(cpu, cpu_smt_mask(core)) {
> > - __cpumask_clear_cpu(cpu, cpus);
> > - if (!available_idle_cpu(cpu))
> > + if (!available_idle_cpu(cpu)) {
> > idle = false;
> > + break;
> > + }
> > }
> > + cpumask_andnot(cpus, cpus, cpu_smt_mask(core));
> >
> > if (idle)
> > return core;
> > --
> > 2.18.1
> >

--
Thanks and Regards
Srikar Dronamraju

\
 
 \ /
  Last update: 2019-12-05 18:52    [W:0.065 / U:2.684 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site