Re: [PATCH 5/6] cgroup/cpuset: Free DL BW in case can_attach() fails
From: Waiman Long
Date: Wed Mar 29 2023 - 10:37:27 EST
On 3/29/23 08:55, Juri Lelli wrote:
From: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx>
---
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;
}