Messages in this thread | | | Date | Thu, 5 Dec 2019 23:21:53 +0530 | From | Srikar Dronamraju <> | Subject | Re: [PATCH] sched/fair: Optimize select_idle_core |
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* 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
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