| From ed6bf03caffc0b20cdad3095b9a92aec03dc614f Mon Sep 17 00:00:00 2001 |
| From: Peter Zijlstra <peterz@infradead.org> |
| Date: Tue, 17 Nov 2020 18:19:32 -0500 |
| Subject: [PATCH] FROMLIST: sched: Introduce sched_class::pick_task() |
| |
| Because sched_class::pick_next_task() also implies |
| sched_class::set_next_task() (and possibly put_prev_task() and |
| newidle_balance) it is not state invariant. This makes it unsuitable |
| for remote task selection. |
| |
| BUG=b:152605392 |
| TEST=run power_VideoCall test |
| |
| (am from |
| https://lore.kernel.org/lkml/20210422123308.437092775@infradead.org/) |
| |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| [Vineeth: folded fixes] |
| Signed-off-by: Vineeth Remanan Pillai <viremana@linux.microsoft.com> |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Tested-by: Don Hiatt <dhiatt@digitalocean.com> |
| Signed-off-by: Joel Fernandes <joelaf@google.com> |
| Change-Id: Idc3cc6a50b07aee3a8bd3c5f565b6fc6e2d121e6 |
| Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2880783 |
| Reviewed-by: Sonny Rao <sonnyrao@chromium.org> |
| --- |
| kernel/sched/deadline.c | 16 ++++++++++++++-- |
| kernel/sched/fair.c | 40 +++++++++++++++++++++++++++++++++++++--- |
| kernel/sched/idle.c | 8 ++++++++ |
| kernel/sched/rt.c | 15 +++++++++++++-- |
| kernel/sched/sched.h | 3 +++ |
| kernel/sched/stop_task.c | 14 ++++++++++++-- |
| 6 files changed, 87 insertions(+), 9 deletions(-) |
| |
| diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c |
| index 37924e0ce872..78c1bbd62099 100644 |
| --- a/kernel/sched/deadline.c |
| +++ b/kernel/sched/deadline.c |
| @@ -1852,7 +1852,7 @@ static struct sched_dl_entity *pick_next_dl_entity(struct rq *rq, |
| return rb_entry(left, struct sched_dl_entity, rb_node); |
| } |
| |
| -static struct task_struct *pick_next_task_dl(struct rq *rq) |
| +static struct task_struct *pick_task_dl(struct rq *rq) |
| { |
| struct sched_dl_entity *dl_se; |
| struct dl_rq *dl_rq = &rq->dl; |
| @@ -1864,7 +1864,18 @@ static struct task_struct *pick_next_task_dl(struct rq *rq) |
| dl_se = pick_next_dl_entity(rq, dl_rq); |
| BUG_ON(!dl_se); |
| p = dl_task_of(dl_se); |
| - set_next_task_dl(rq, p, true); |
| + |
| + return p; |
| +} |
| + |
| +static struct task_struct *pick_next_task_dl(struct rq *rq) |
| +{ |
| + struct task_struct *p; |
| + |
| + p = pick_task_dl(rq); |
| + if (p) |
| + set_next_task_dl(rq, p, true); |
| + |
| return p; |
| } |
| |
| @@ -2539,6 +2550,7 @@ DEFINE_SCHED_CLASS(dl) = { |
| |
| #ifdef CONFIG_SMP |
| .balance = balance_dl, |
| + .pick_task = pick_task_dl, |
| .select_task_rq = select_task_rq_dl, |
| .migrate_task_rq = migrate_task_rq_dl, |
| .set_cpus_allowed = set_cpus_allowed_dl, |
| diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c |
| index b2055065c276..9bb7100360c3 100644 |
| --- a/kernel/sched/fair.c |
| +++ b/kernel/sched/fair.c |
| @@ -4419,6 +4419,8 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| static void |
| set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se) |
| { |
| + clear_buddies(cfs_rq, se); |
| + |
| /* 'current' is not kept within the tree. */ |
| if (se->on_rq) { |
| /* |
| @@ -4478,7 +4480,7 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| * Avoid running the skip buddy, if running something else can |
| * be done without getting too unfair. |
| */ |
| - if (cfs_rq->skip == se) { |
| + if (cfs_rq->skip && cfs_rq->skip == se) { |
| struct sched_entity *second; |
| |
| if (se == curr) { |
| @@ -4505,8 +4507,6 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) |
| se = cfs_rq->last; |
| } |
| |
| - clear_buddies(cfs_rq, se); |
| - |
| return se; |
| } |
| |
| @@ -7089,6 +7089,39 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ |
| set_last_buddy(se); |
| } |
| |
| +#ifdef CONFIG_SMP |
| +static struct task_struct *pick_task_fair(struct rq *rq) |
| +{ |
| + struct sched_entity *se; |
| + struct cfs_rq *cfs_rq; |
| + |
| +again: |
| + cfs_rq = &rq->cfs; |
| + if (!cfs_rq->nr_running) |
| + return NULL; |
| + |
| + do { |
| + struct sched_entity *curr = cfs_rq->curr; |
| + |
| + /* When we pick for a remote RQ, we'll not have done put_prev_entity() */ |
| + if (curr) { |
| + if (curr->on_rq) |
| + update_curr(cfs_rq); |
| + else |
| + curr = NULL; |
| + |
| + if (unlikely(check_cfs_rq_runtime(cfs_rq))) |
| + goto again; |
| + } |
| + |
| + se = pick_next_entity(cfs_rq, curr); |
| + cfs_rq = group_cfs_rq(se); |
| + } while (cfs_rq); |
| + |
| + return task_of(se); |
| +} |
| +#endif |
| + |
| struct task_struct * |
| pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) |
| { |
| @@ -11283,6 +11316,7 @@ DEFINE_SCHED_CLASS(fair) = { |
| |
| #ifdef CONFIG_SMP |
| .balance = balance_fair, |
| + .pick_task = pick_task_fair, |
| .select_task_rq = select_task_rq_fair, |
| .migrate_task_rq = migrate_task_rq_fair, |
| |
| diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c |
| index 0194768ea9e7..43646e7876d9 100644 |
| --- a/kernel/sched/idle.c |
| +++ b/kernel/sched/idle.c |
| @@ -439,6 +439,13 @@ static void set_next_task_idle(struct rq *rq, struct task_struct *next, bool fir |
| schedstat_inc(rq->sched_goidle); |
| } |
| |
| +#ifdef CONFIG_SMP |
| +static struct task_struct *pick_task_idle(struct rq *rq) |
| +{ |
| + return rq->idle; |
| +} |
| +#endif |
| + |
| struct task_struct *pick_next_task_idle(struct rq *rq) |
| { |
| struct task_struct *next = rq->idle; |
| @@ -506,6 +513,7 @@ DEFINE_SCHED_CLASS(idle) = { |
| |
| #ifdef CONFIG_SMP |
| .balance = balance_idle, |
| + .pick_task = pick_task_idle, |
| .select_task_rq = select_task_rq_idle, |
| .set_cpus_allowed = set_cpus_allowed_common, |
| #endif |
| diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c |
| index 60f5503a24a9..061e39d63773 100644 |
| --- a/kernel/sched/rt.c |
| +++ b/kernel/sched/rt.c |
| @@ -1626,7 +1626,7 @@ static struct task_struct *_pick_next_task_rt(struct rq *rq) |
| return rt_task_of(rt_se); |
| } |
| |
| -static struct task_struct *pick_next_task_rt(struct rq *rq) |
| +static struct task_struct *pick_task_rt(struct rq *rq) |
| { |
| struct task_struct *p; |
| |
| @@ -1634,7 +1634,17 @@ static struct task_struct *pick_next_task_rt(struct rq *rq) |
| return NULL; |
| |
| p = _pick_next_task_rt(rq); |
| - set_next_task_rt(rq, p, true); |
| + |
| + return p; |
| +} |
| + |
| +static struct task_struct *pick_next_task_rt(struct rq *rq) |
| +{ |
| + struct task_struct *p = pick_task_rt(rq); |
| + |
| + if (p) |
| + set_next_task_rt(rq, p, true); |
| + |
| return p; |
| } |
| |
| @@ -2483,6 +2493,7 @@ DEFINE_SCHED_CLASS(rt) = { |
| |
| #ifdef CONFIG_SMP |
| .balance = balance_rt, |
| + .pick_task = pick_task_rt, |
| .select_task_rq = select_task_rq_rt, |
| .set_cpus_allowed = set_cpus_allowed_common, |
| .rq_online = rq_online_rt, |
| diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h |
| index 9a18f07ec925..ea47a3385997 100644 |
| --- a/kernel/sched/sched.h |
| +++ b/kernel/sched/sched.h |
| @@ -1952,6 +1952,9 @@ struct sched_class { |
| |
| #ifdef CONFIG_SMP |
| int (*balance)(struct rq *rq, struct task_struct *prev, struct rq_flags *rf); |
| + |
| + struct task_struct * (*pick_task)(struct rq *rq); |
| + |
| int (*select_task_rq)(struct task_struct *p, int task_cpu, int flags); |
| void (*migrate_task_rq)(struct task_struct *p, int new_cpu); |
| |
| diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c |
| index 55f39125c0e1..f988ebe3febb 100644 |
| --- a/kernel/sched/stop_task.c |
| +++ b/kernel/sched/stop_task.c |
| @@ -34,15 +34,24 @@ static void set_next_task_stop(struct rq *rq, struct task_struct *stop, bool fir |
| stop->se.exec_start = rq_clock_task(rq); |
| } |
| |
| -static struct task_struct *pick_next_task_stop(struct rq *rq) |
| +static struct task_struct *pick_task_stop(struct rq *rq) |
| { |
| if (!sched_stop_runnable(rq)) |
| return NULL; |
| |
| - set_next_task_stop(rq, rq->stop, true); |
| return rq->stop; |
| } |
| |
| +static struct task_struct *pick_next_task_stop(struct rq *rq) |
| +{ |
| + struct task_struct *p = pick_task_stop(rq); |
| + |
| + if (p) |
| + set_next_task_stop(rq, p, true); |
| + |
| + return p; |
| +} |
| + |
| static void |
| enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags) |
| { |
| @@ -123,6 +132,7 @@ DEFINE_SCHED_CLASS(stop) = { |
| |
| #ifdef CONFIG_SMP |
| .balance = balance_stop, |
| + .pick_task = pick_task_stop, |
| .select_task_rq = select_task_rq_stop, |
| .set_cpus_allowed = set_cpus_allowed_common, |
| #endif |
| -- |
| 2.31.1.818.g46aad6cb9e-goog |
| |