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Mon, 08 Jun 2026 05:15:59 -0700 (PDT) From: Yuri Andriaccio To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Tejun Heo , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= Cc: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Luca Abeni , Yuri Andriaccio Subject: [RFC PATCH v6 12/25] sched/rt: Add {alloc/unregister/free}_rt_sched_group Date: Mon, 8 Jun 2026 14:15:31 +0200 Message-ID: <20260608121546.69910-13-yurand2000@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260608121546.69910-1-yurand2000@gmail.com> References: <20260608121546.69910-1-yurand2000@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add allocation and deallocation code for rt-cgroups. Declare dl_server specific functions (only skeleton, but no implementation yet), needed by the deadline servers to be called when trying to schedule. Initialize a cgroup's active context to that of its parent. Co-developed-by: Alessio Balsini Signed-off-by: Alessio Balsini Co-developed-by: Andrea Parri Signed-off-by: Andrea Parri Co-developed-by: luca abeni Signed-off-by: luca abeni Signed-off-by: Yuri Andriaccio --- kernel/sched/rt.c | 156 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 154 insertions(+), 2 deletions(-) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index dbba7a57d6f1..a6adf21772a6 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -120,24 +120,176 @@ struct dl_bandwidth *dl_bandwidth_write(struct task_group *tg) void unregister_rt_sched_group(struct task_group *tg) { + int i; + + if (!rt_group_sched_enabled()) + return; + + if (!tg->dl_se || !tg->rt_rq) + return; + for_each_possible_cpu(i) { + if (!tg->dl_se[i] || !tg->rt_rq[i]) + continue; + + if (tg->dl_se[i]->dl_runtime) + dl_init_tg(tg->dl_se[i], 0, tg->dl_se[i]->dl_period); + } } void free_rt_sched_group(struct task_group *tg) { + int i; + unsigned long flags; + if (!rt_group_sched_enabled()) return; + + if (!tg->dl_se || !tg->rt_rq) + return; + + for_each_possible_cpu(i) { + if (!tg->dl_se[i] || !tg->rt_rq[i]) + continue; + + /* + * Shutdown the dl_server and free it + * + * Since the dl timer is going to be cancelled, + * we risk to never decrease the running bw... + * Fix this issue by changing the group runtime + * to 0 immediately before freeing it. + */ + if (tg->dl_se[i]->dl_runtime) + dl_init_tg(tg->dl_se[i], 0, tg->dl_se[i]->dl_period); + + raw_spin_rq_lock_irqsave(cpu_rq(i), flags); + hrtimer_cancel(&tg->dl_se[i]->dl_timer); + raw_spin_rq_unlock_irqrestore(cpu_rq(i), flags); + kfree(tg->dl_se[i]); + + /* Free the local per-cpu runqueue */ + kfree(rq_of_rt_rq(tg->rt_rq[i])); + } + + kfree(tg->rt_rq); + kfree(tg->dl_se); } +static inline void __rt_rq_free(struct rt_rq **rt_rq) +{ + int i; + + for_each_possible_cpu(i) { + kfree(rq_of_rt_rq(rt_rq[i])); + } + + kfree(rt_rq); +} + +DEFINE_FREE(rt_rq_free, struct rt_rq **, if (_T) __rt_rq_free(_T)) + +static inline void __dl_se_free(struct sched_dl_entity **dl_se) +{ + int i; + + for_each_possible_cpu(i) { + kfree(dl_se[i]); + } + + kfree(dl_se); +} + +DEFINE_FREE(dl_se_free, struct sched_dl_entity **, if (_T) __dl_se_free(_T)) + +static int __alloc_rt_sched_group_data(struct task_group *tg) { + /* Instantiate automatic cleanup in event of kalloc fail */ + struct rt_rq **tg_rt_rq __free(rt_rq_free) = NULL; + struct sched_dl_entity **tg_dl_se __free(dl_se_free) = NULL; + struct sched_dl_entity *dl_se __free(kfree) = NULL; + struct rq *s_rq __free(kfree) = NULL; + int i; + + tg_rt_rq = kcalloc(nr_cpu_ids, sizeof(struct rt_rq *), GFP_KERNEL); + if (!tg_rt_rq) + return 0; + + tg_dl_se = kcalloc(nr_cpu_ids, + sizeof(struct sched_dl_entity *), GFP_KERNEL); + if (!tg_dl_se) + return 0; + + for_each_possible_cpu(i) { + s_rq = kzalloc_node(sizeof(struct rq), + GFP_KERNEL, cpu_to_node(i)); + if (!s_rq) + return 0; + + dl_se = kzalloc_node(sizeof(struct sched_dl_entity), + GFP_KERNEL, cpu_to_node(i)); + if (!dl_se) + return 0; + + tg_rt_rq[i] = &no_free_ptr(s_rq)->rt; + tg_dl_se[i] = no_free_ptr(dl_se); + } + + tg->rt_rq = no_free_ptr(tg_rt_rq); + tg->dl_se = no_free_ptr(tg_dl_se); + + return 1; +} + +static struct task_struct *rt_server_pick(struct sched_dl_entity *dl_se, struct rq_flags *rf); + int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) { + struct sched_dl_entity *dl_se; + struct rq *s_rq; + int i; + if (!rt_group_sched_enabled()) return 1; + /* Allocate all necessary resources beforehand */ + if (!__alloc_rt_sched_group_data(tg)) + return 0; + + /* Initialize the allocated resources now. */ + scoped_guard(raw_spinlock_irq, dl_bw_lock_of_tg(parent)) { + init_dl_bandwidth(&tg->dl_bandwidth, 0, RUNTIME_INF, + dl_bandwidth_read(parent)->active_context); + } + + for_each_possible_cpu(i) { + s_rq = rq_of_rt_rq(tg->rt_rq[i]); + dl_se = tg->dl_se[i]; + + init_rt_rq(&s_rq->rt); + s_rq->cpu = i; + s_rq->rt.tg = tg; + + init_dl_entity(dl_se); + dl_se->dl_runtime = 0; + dl_se->dl_deadline = 0; + dl_se->dl_period = 0; + dl_se->runtime = 0; + dl_se->deadline = 0; + dl_se->dl_bw = to_ratio(dl_se->dl_period, dl_se->dl_runtime); + dl_se->dl_density = to_ratio(dl_se->dl_deadline, dl_se->dl_runtime); + dl_se->dl_server = 1; + dl_server_init(dl_se, &cpu_rq(i)->dl, s_rq, rt_server_pick); + } + return 1; } -#else /* !CONFIG_RT_GROUP_SCHED: */ +static struct task_struct *rt_server_pick(struct sched_dl_entity *dl_se, struct rq_flags *rf) +{ + return NULL; +} + +#else /* !CONFIG_RT_GROUP_SCHED */ void unregister_rt_sched_group(struct task_group *tg) { } @@ -147,7 +299,7 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent) { return 1; } -#endif /* !CONFIG_RT_GROUP_SCHED */ +#endif /* CONFIG_RT_GROUP_SCHED */ static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev) { -- 2.54.0