Always account for both the ext_server and fair_server bandwidth, especially during CPU hotplug operations.
Ignoring either can lead to imbalances in total_bw when sched_ext schedulers are active and CPUs are brought online / offline. Signed-off-by: Andrea Righi <[email protected]> --- kernel/sched/deadline.c | 54 +++++++++++++++++++++++++++++++---------- kernel/sched/topology.c | 5 ++++ 2 files changed, 46 insertions(+), 13 deletions(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 6ecfaaa1f912d..f786174a126c8 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -2994,6 +2994,36 @@ void dl_add_task_root_domain(struct task_struct *p) task_rq_unlock(rq, p, &rf); } +static void dl_server_add_bw(struct root_domain *rd, int cpu) +{ + struct sched_dl_entity *dl_se; + + dl_se = &cpu_rq(cpu)->fair_server; + if (dl_server(dl_se)) + __dl_add(&rd->dl_bw, dl_se->dl_bw, dl_bw_cpus(cpu)); + +#ifdef CONFIG_SCHED_CLASS_EXT + dl_se = &cpu_rq(cpu)->ext_server; + if (dl_server(dl_se)) + __dl_add(&rd->dl_bw, dl_se->dl_bw, dl_bw_cpus(cpu)); +#endif +} + +static u64 dl_server_read_bw(int cpu) +{ + u64 dl_bw = 0; + + if (cpu_rq(cpu)->fair_server.dl_server) + dl_bw += cpu_rq(cpu)->fair_server.dl_bw; + +#ifdef CONFIG_SCHED_CLASS_EXT + if (cpu_rq(cpu)->ext_server.dl_server) + dl_bw += cpu_rq(cpu)->ext_server.dl_bw; +#endif + + return dl_bw; +} + void dl_clear_root_domain(struct root_domain *rd) { int i; @@ -3013,10 +3043,9 @@ void dl_clear_root_domain(struct root_domain *rd) * them, we need to account for them here explicitly. */ for_each_cpu(i, rd->span) { - struct sched_dl_entity *dl_se = &cpu_rq(i)->fair_server; - - if (dl_server(dl_se) && cpu_active(i)) - __dl_add(&rd->dl_bw, dl_se->dl_bw, dl_bw_cpus(i)); + if (!cpu_active(i)) + continue; + dl_server_add_bw(rd, i); } } @@ -3513,7 +3542,7 @@ static int dl_bw_manage(enum dl_bw_request req, int cpu, u64 dl_bw) unsigned long flags, cap; struct dl_bw *dl_b; bool overflow = 0; - u64 fair_server_bw = 0; + u64 dl_server_bw = 0; rcu_read_lock_sched(); dl_b = dl_bw_of(cpu); @@ -3546,27 +3575,26 @@ static int dl_bw_manage(enum dl_bw_request req, int cpu, u64 dl_bw) cap -= arch_scale_cpu_capacity(cpu); /* - * cpu is going offline and NORMAL tasks will be moved away - * from it. We can thus discount dl_server bandwidth - * contribution as it won't need to be servicing tasks after - * the cpu is off. + * cpu is going offline and NORMAL and EXT tasks will be + * moved away from it. We can thus discount dl_server + * bandwidth contribution as it won't need to be servicing + * tasks after the cpu is off. */ - if (cpu_rq(cpu)->fair_server.dl_server) - fair_server_bw = cpu_rq(cpu)->fair_server.dl_bw; + dl_server_bw = dl_server_read_bw(cpu); /* * Not much to check if no DEADLINE bandwidth is present. * dl_servers we can discount, as tasks will be moved out the * offlined CPUs anyway. */ - if (dl_b->total_bw - fair_server_bw > 0) { + if (dl_b->total_bw - dl_server_bw > 0) { /* * Leaving at least one CPU for DEADLINE tasks seems a * wise thing to do. As said above, cpu is not offline * yet, so account for that. */ if (dl_bw_cpus(cpu) - 1) - overflow = __dl_overflow(dl_b, cap, fair_server_bw, 0); + overflow = __dl_overflow(dl_b, cap, dl_server_bw, 0); else overflow = 1; } diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 711076aa49801..1ec8e74b80219 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -508,6 +508,11 @@ void rq_attach_root(struct rq *rq, struct root_domain *rd) if (rq->fair_server.dl_server) __dl_server_attach_root(&rq->fair_server, rq); +#ifdef CONFIG_SCHED_CLASS_EXT + if (rq->ext_server.dl_server) + __dl_server_attach_root(&rq->ext_server, rq); +#endif + rq_unlock_irqrestore(rq, &rf); if (old_rd) -- 2.51.2
