Messages in this thread | | | Date | Wed, 29 Mar 2023 10:25:07 -0400 | Subject | Re: [PATCH 5/6] cgroup/cpuset: Free DL BW in case can_attach() fails | From | Waiman Long <> |
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On 3/29/23 08:55, Juri Lelli wrote: > From: Dietmar Eggemann <dietmar.eggemann@arm.com> > > cpuset_can_attach() can fail. Postpone DL BW allocation until all tasks > have been checked. DL BW is not allocated per-task but as a sum over > all DL tasks migrating. > > If multiple controllers are attached to the cgroup next to the cuset Typo: : "cuset" => "cpuset" > controller a non-cpuset can_attach() can fail. In this case free DL BW > in cpuset_cancel_attach(). > > Finally, update cpuset DL task count (nr_deadline_tasks) only in > cpuset_attach(). > > Suggested-by: Waiman Long <longman@redhat.com> > Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com> > Signed-off-by: Juri Lelli <juri.lelli@redhat.com> > --- > include/linux/sched.h | 2 +- > kernel/cgroup/cpuset.c | 55 ++++++++++++++++++++++++++++++++++++++---- > kernel/sched/core.c | 17 ++----------- > 3 files changed, 53 insertions(+), 21 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 6f3d84e0ed08..50cbbfefbe11 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -1847,7 +1847,7 @@ current_restore_flags(unsigned long orig_flags, unsigned long flags) > } > > extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial); > -extern int task_can_attach(struct task_struct *p, const struct cpumask *cs_effective_cpus); > +extern int task_can_attach(struct task_struct *p); > extern int dl_bw_alloc(int cpu, u64 dl_bw); > extern void dl_bw_free(int cpu, u64 dl_bw); > #ifdef CONFIG_SMP > diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c > index eb0854ef9757..f8ebec66da51 100644 > --- a/kernel/cgroup/cpuset.c > +++ b/kernel/cgroup/cpuset.c > @@ -198,6 +198,8 @@ struct cpuset { > * know when to rebuild associated root domain bandwidth information. > */ > int nr_deadline_tasks; > + int nr_migrate_dl_tasks; > + u64 sum_migrate_dl_bw; > > /* Invalid partition error code, not lock protected */ > enum prs_errcode prs_err; > @@ -2464,16 +2466,23 @@ static int fmeter_getrate(struct fmeter *fmp) > > static struct cpuset *cpuset_attach_old_cs; > > +static void reset_migrate_dl_data(struct cpuset *cs) > +{ > + cs->nr_migrate_dl_tasks = 0; > + cs->sum_migrate_dl_bw = 0; > +} > + > /* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */ > static int cpuset_can_attach(struct cgroup_taskset *tset) > { > struct cgroup_subsys_state *css; > - struct cpuset *cs; > + struct cpuset *cs, *oldcs; > struct task_struct *task; > int ret; > > /* used later by cpuset_attach() */ > cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css)); > + oldcs = cpuset_attach_old_cs; > cs = css_cs(css); > > mutex_lock(&cpuset_mutex); > @@ -2491,7 +2500,7 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) > goto out_unlock; > > cgroup_taskset_for_each(task, css, tset) { > - ret = task_can_attach(task, cs->effective_cpus); > + ret = task_can_attach(task); > if (ret) > goto out_unlock; > ret = security_task_setscheduler(task); > @@ -2499,11 +2508,31 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) > goto out_unlock; > > if (dl_task(task)) { > - cs->nr_deadline_tasks++; > - cpuset_attach_old_cs->nr_deadline_tasks--; > + cs->nr_migrate_dl_tasks++; > + cs->sum_migrate_dl_bw += task->dl.dl_bw; > + } > + } > + > + if (!cs->nr_migrate_dl_tasks) > + goto out_succes; > + > + if (!cpumask_intersects(oldcs->effective_cpus, cs->effective_cpus)) { > + int cpu = cpumask_any_and(cpu_active_mask, cs->effective_cpus); > + > + if (unlikely(cpu >= nr_cpu_ids)) { > + reset_migrate_dl_data(cs); > + ret = -EINVAL; > + goto out_unlock; > + } > + > + ret = dl_bw_alloc(cpu, cs->sum_migrate_dl_bw); > + if (ret) { > + reset_migrate_dl_data(cs); > + goto out_unlock; > } > } > > +out_succes: > /* > * Mark attach is in progress. This makes validate_change() fail > * changes which zero cpus/mems_allowed. > @@ -2518,11 +2547,21 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) > static void cpuset_cancel_attach(struct cgroup_taskset *tset) > { > struct cgroup_subsys_state *css; > + struct cpuset *cs; > > cgroup_taskset_first(tset, &css); > + cs = css_cs(css); > > mutex_lock(&cpuset_mutex); > - css_cs(css)->attach_in_progress--; > + cs->attach_in_progress--; > + > + if (cs->nr_migrate_dl_tasks) { > + int cpu = cpumask_any(cs->effective_cpus); > + > + dl_bw_free(cpu, cs->sum_migrate_dl_bw); > + reset_migrate_dl_data(cs); > + } > + > mutex_unlock(&cpuset_mutex); > } > > @@ -2617,6 +2656,12 @@ static void cpuset_attach(struct cgroup_taskset *tset) > out: > cs->old_mems_allowed = cpuset_attach_nodemask_to; > > + if (cs->nr_migrate_dl_tasks) { > + cs->nr_deadline_tasks += cs->nr_migrate_dl_tasks; > + oldcs->nr_deadline_tasks -= cs->nr_migrate_dl_tasks; > + reset_migrate_dl_data(cs); > + } > + > cs->attach_in_progress--; > if (!cs->attach_in_progress) > wake_up(&cpuset_attach_wq); > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index c83dae6b8586..10454980e830 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -9269,8 +9269,7 @@ int cpuset_cpumask_can_shrink(const struct cpumask *cur, > return ret; > } > > -int task_can_attach(struct task_struct *p, > - const struct cpumask *cs_effective_cpus) > +int task_can_attach(struct task_struct *p) > { > int ret = 0; > > @@ -9283,21 +9282,9 @@ int task_can_attach(struct task_struct *p, > * success of set_cpus_allowed_ptr() on all attached tasks > * before cpus_mask may be changed. > */ > - if (p->flags & PF_NO_SETAFFINITY) { > + if (p->flags & PF_NO_SETAFFINITY) > ret = -EINVAL; > - goto out; > - } > - > - if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span, > - cs_effective_cpus)) { > - int cpu = cpumask_any_and(cpu_active_mask, cs_effective_cpus); > > - if (unlikely(cpu >= nr_cpu_ids)) > - return -EINVAL; > - ret = dl_bw_alloc(cpu, p->dl.dl_bw); > - } > - > -out: > return ret; > } >
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