On 1/15/21 3:36 PM, Dietmar Eggemann wrote:
> On 12/01/2021 16:53, Daniel Bristot de Oliveira wrote:
>
> [...]
>
>> ----- %< -----
>> #!/bin/bash
>> # Enter on the cgroup directory
>> cd /sys/fs/cgroup/
>>
>> # Check it if is cgroup v2 and enable cpuset
>> if [ -e cgroup.subtree_control ]; then
>> # Enable cpuset controller on cgroup v2
>> echo +cpuset > cgroup.subtree_control
>> fi
>>
>> echo LOG: create an exclusive cpuset and assigned the CPU 0 to it
>> # Create cpuset groups
>> rmdir dl-group &> /dev/null
>> mkdir dl-group
>>
>> # Restrict the task to the CPU 0
>> echo 0 > dl-group/cpuset.mems
>> echo 0 > dl-group/cpuset.cpus
>> echo root > dl-group/cpuset.cpus.partition
>>
>> echo LOG: dispatching a regular task
>> sleep 100 &
>> CPUSET_PID="$!"
>>
>> # let it settle down
>> sleep 1
>>
>> # Assign the second task to the cgroup
>
> There is only one task 'CPUSET_PID' involved here?
Ooops, yep, I will remove the "second" part.
>> echo LOG: moving the second DL task to the cpuset
>> echo "$CPUSET_PID" > dl-group/cgroup.procs 2> /dev/null
>>
>> CPUSET_ALLOWED=`cat /proc/$CPUSET_PID/status | grep Cpus_allowed_list | awk '{print $2}'`
>>
>> chrt -p -d --sched-period 1000000000 --sched-runtime 100000000 0 $CPUSET_PID
>> ACCEPTED=$?
>>
>> if [ $ACCEPTED == 0 ]; then
>> echo PASS: the task became DL
>> else
>> echo FAIL: the task was rejected as DL
>> fi
>
> [...]
>
>> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
>> index 5961a97541c2..3c2775e6869f 100644
>> --- a/kernel/sched/core.c
>> +++ b/kernel/sched/core.c
>> @@ -5905,15 +5905,15 @@ static int __sched_setscheduler(struct task_struct *p,
>> #ifdef CONFIG_SMP
>> if (dl_bandwidth_enabled() && dl_policy(policy) &&
>> !(attr->sched_flags & SCHED_FLAG_SUGOV)) {
>> - cpumask_t *span = rq->rd->span;
>> + struct root_domain *rd = dl_task_rd(p);
>>
>> /*
>> * Don't allow tasks with an affinity mask smaller than
>> * the entire root_domain to become SCHED_DEADLINE. We
>> * will also fail if there's no bandwidth available.
>> */
>> - if (!cpumask_subset(span, p->cpus_ptr) ||
>> - rq->rd->dl_bw.bw == 0) {
>> + if (!cpumask_subset(rd->span, p->cpus_ptr) ||
>> + rd->dl_bw.bw == 0) {
>> retval = -EPERM;
>> goto unlock;
>> }
>> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
>> index c221e14d5b86..1f6264cb8867 100644
>> --- a/kernel/sched/deadline.c
>> +++ b/kernel/sched/deadline.c
>> @@ -2678,8 +2678,8 @@ int sched_dl_overflow(struct task_struct *p, int policy,
>> u64 period = attr->sched_period ?: attr->sched_deadline;
>> u64 runtime = attr->sched_runtime;
>> u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
>> - int cpus, err = -1, cpu = task_cpu(p);
>> - struct dl_bw *dl_b = dl_bw_of(cpu);
>> + int cpus, err = -1, cpu = dl_task_cpu(p);
>> + struct dl_bw *dl_b = dl_task_root_bw(p);
>> unsigned long cap;
>>
>> if (attr->sched_flags & SCHED_FLAG_SUGOV)
>>
>
> Wouldn't it be sufficient to just introduce dl_task_cpu() and use the
> correct cpu to get rd->span or struct dl_bw in __sched_setscheduler()
> -> sched_dl_overflow()?
While I think that having the dl_task_rd() makes the code more intuitive, I have
no problem on not adding it...
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 5961a97541c2..0573f676696a 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -5905,7 +5905,8 @@ static int __sched_setscheduler(struct task_struct *p,
> #ifdef CONFIG_SMP
> if (dl_bandwidth_enabled() && dl_policy(policy) &&
> !(attr->sched_flags & SCHED_FLAG_SUGOV)) {
> - cpumask_t *span = rq->rd->span;
> + int cpu = dl_task_cpu(p);
> + cpumask_t *span = cpu_rq(cpu)->rd->span;
>
> /*
> * Don't allow tasks with an affinity mask smaller than
> diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
> index c221e14d5b86..308ecaaf3d28 100644
> --- a/kernel/sched/deadline.c
> +++ b/kernel/sched/deadline.c
> @@ -2678,7 +2678,7 @@ int sched_dl_overflow(struct task_struct *p, int policy,
> u64 period = attr->sched_period ?: attr->sched_deadline;
> u64 runtime = attr->sched_runtime;
> u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0;
> - int cpus, err = -1, cpu = task_cpu(p);
> + int cpus, err = -1, cpu = dl_task_cpu(p);
> struct dl_bw *dl_b = dl_bw_of(cpu);
> unsigned long cap;
>
This way works for me too.
Thanks!
-- Daniel
