From nobody Mon Nov 25 05:43:03 2024 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E8A33213ED9 for ; Wed, 30 Oct 2024 15:25:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730301956; cv=none; b=DlIl1QpM8jnSqac5ypF5ZqDx+3lkl0zLmDsHiqt2jGR9Qua+rIXlqSKCc79XaFt7TZRZTlh6M43NKM2c+P1rHzP383gxJo2u7d+L9ZeVO09m7QOyitff2J2vMWY0jHzj/YjOEQ881WiNS4mSuer0Nu88f83MRfGWjwAZlfCysQQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730301956; c=relaxed/simple; bh=mccBWL9WEoEDXhSL3qlwPQc6HCn5mfi3S4mWhduGjio=; h=Message-Id:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=aA7q8V+eJy7bFYwDciLU+yURNsPE30NlS2U2m9wfpd5dm7EAtt2/kh3H10XM4F/enCVhxtYeRTM1OUS4CwAvJ8NDGuazRtotc9IesYoz7Y/l730ajYP+kH10LKRG4q3zRDIwh3HyczedpL9vyAIe/1+ThIHjkqWzxruLCII6l0s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=N7wIEeVd; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="N7wIEeVd" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Type:MIME-Version:References: Subject:Cc:To:From:Date:Message-Id:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:In-Reply-To; bh=CENJfiIAjzpdW6w2/RkM/sIExyk1ul4yI9JaIDui0rk=; b=N7wIEeVdgULIyi7njLxxIBobBo BYg1apHI1COlEDCc6v/9zL2vMyDI2H3zeUlYdv9X65FHd+gUFf86aJJcQQMmhDyArZtNfSFTTag5M rOkT10ge9VT1kgPcDJzyFFSnNDuWrAo/fG8Vp6m5dvHRL617i1aIiVyhlOWgGP1vggBn4jEKwFOrG m+XaVCf/OJgN4GDVaeCiJkrkFvtsk1Geto8lLVLnjbCXYpiEDSXbE6vhHN35WJ9JWGIOXibDO/qfi PI04I0JAPQ2nV3oHVQWMI7lGlKIKLzTZpp5SxFPYxqkM+WmavZCrO+P43Wwjew787HNn4FL+Ploee VN+gSdZA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1t6AZs-0000000AI26-3P15; Wed, 30 Oct 2024 15:25:45 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 0) id DEF72301173; Wed, 30 Oct 2024 16:25:43 +0100 (CET) Message-Id: <20241030152142.488737132@infradead.org> User-Agent: quilt/0.65 Date: Wed, 30 Oct 2024 16:12:57 +0100 From: Peter Zijlstra To: mingo@kernel.org Cc: peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, tj@kernel.org, void@manifault.com, linux-kernel@vger.kernel.org Subject: [RFC][PATCH 2/6] sched: Employ sched_change guards References: <20241030151255.300069509@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" As proposed a long while ago -- and half done by scx -- wrap the scheduler's 'change' pattern in a guard helper. Signed-off-by: Peter Zijlstra (Intel) --- include/linux/cleanup.h | 5 + kernel/sched/core.c | 158 ++++++++++++++++++-------------------------= ----- kernel/sched/ext.c | 33 +++------- kernel/sched/sched.h | 21 +++--- kernel/sched/syscalls.c | 65 ++++++------------- 5 files changed, 112 insertions(+), 170 deletions(-) --- a/include/linux/cleanup.h +++ b/include/linux/cleanup.h @@ -297,6 +297,11 @@ static inline class_##_name##_t class_## #define __DEFINE_CLASS_IS_CONDITIONAL(_name, _is_cond) \ static __maybe_unused const bool class_##_name##_is_conditional =3D _is_co= nd =20 +#define DEFINE_CLASS_IS_UNCONDITIONAL(_name) \ + __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ + static inline void * class_##_name##_lock_ptr(class_##_name##_t *_T) \ + { return (void *)1; } + #define DEFINE_GUARD(_name, _type, _lock, _unlock) \ __DEFINE_CLASS_IS_CONDITIONAL(_name, false); \ DEFINE_CLASS(_name, _type, if (_T) { _unlock; }, ({ _lock; _T; }), _type = _T); \ --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7099,7 +7099,7 @@ void rt_mutex_post_schedule(void) */ void rt_mutex_setprio(struct task_struct *p, struct task_struct *pi_task) { - int prio, oldprio, queued, running, queue_flag =3D + int prio, oldprio, queue_flag =3D DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; const struct sched_class *prev_class, *next_class; struct rq_flags rf; @@ -7164,52 +7164,42 @@ void rt_mutex_setprio(struct task_struct if (prev_class !=3D next_class && p->se.sched_delayed) dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); =20 - queued =3D task_on_rq_queued(p); - running =3D task_current_donor(rq, p); - if (queued) - dequeue_task(rq, p, queue_flag); - if (running) - put_prev_task(rq, p); - - /* - * Boosting condition are: - * 1. -rt task is running and holds mutex A - * --> -dl task blocks on mutex A - * - * 2. -dl task is running and holds mutex A - * --> -dl task blocks on mutex A and could preempt the - * running task - */ - if (dl_prio(prio)) { - if (!dl_prio(p->normal_prio) || - (pi_task && dl_prio(pi_task->prio) && - dl_entity_preempt(&pi_task->dl, &p->dl))) { - p->dl.pi_se =3D pi_task->dl.pi_se; - queue_flag |=3D ENQUEUE_REPLENISH; + scoped_guard (sched_change, p, queue_flag) { + /* + * Boosting condition are: + * 1. -rt task is running and holds mutex A + * --> -dl task blocks on mutex A + * + * 2. -dl task is running and holds mutex A + * --> -dl task blocks on mutex A and could preempt the + * running task + */ + if (dl_prio(prio)) { + if (!dl_prio(p->normal_prio) || + (pi_task && dl_prio(pi_task->prio) && + dl_entity_preempt(&pi_task->dl, &p->dl))) { + p->dl.pi_se =3D pi_task->dl.pi_se; + scope.flags |=3D ENQUEUE_REPLENISH; + } else { + p->dl.pi_se =3D &p->dl; + } + } else if (rt_prio(prio)) { + if (dl_prio(oldprio)) + p->dl.pi_se =3D &p->dl; + if (oldprio < prio) + scope.flags |=3D ENQUEUE_HEAD; } else { - p->dl.pi_se =3D &p->dl; + if (dl_prio(oldprio)) + p->dl.pi_se =3D &p->dl; + if (rt_prio(oldprio)) + p->rt.timeout =3D 0; } - } else if (rt_prio(prio)) { - if (dl_prio(oldprio)) - p->dl.pi_se =3D &p->dl; - if (oldprio < prio) - queue_flag |=3D ENQUEUE_HEAD; - } else { - if (dl_prio(oldprio)) - p->dl.pi_se =3D &p->dl; - if (rt_prio(oldprio)) - p->rt.timeout =3D 0; - } - - p->sched_class =3D next_class; - p->prio =3D prio; =20 - check_class_changing(rq, p, prev_class); + p->sched_class =3D next_class; + p->prio =3D prio; =20 - if (queued) - enqueue_task(rq, p, queue_flag); - if (running) - set_next_task(rq, p); + check_class_changing(rq, p, prev_class); + } =20 check_class_changed(rq, p, prev_class, oldprio); out_unlock: @@ -7819,26 +7809,9 @@ int migrate_task_to(struct task_struct * */ void sched_setnuma(struct task_struct *p, int nid) { - bool queued, running; - struct rq_flags rf; - struct rq *rq; - - rq =3D task_rq_lock(p, &rf); - queued =3D task_on_rq_queued(p); - running =3D task_current_donor(rq, p); - - if (queued) - dequeue_task(rq, p, DEQUEUE_SAVE); - if (running) - put_prev_task(rq, p); - - p->numa_preferred_nid =3D nid; - - if (queued) - enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); - if (running) - set_next_task(rq, p); - task_rq_unlock(rq, p, &rf); + guard(task_rq_lock)(p); + scoped_guard (sched_change, p, DEQUEUE_SAVE) + p->numa_preferred_nid =3D nid; } #endif /* CONFIG_NUMA_BALANCING */ =20 @@ -8957,9 +8930,10 @@ static void sched_change_group(struct ta */ void sched_move_task(struct task_struct *tsk) { - int queued, running, queue_flags =3D + unsigned int queue_flags =3D DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK; struct task_group *group; + bool resched =3D false; struct rq *rq; =20 CLASS(task_rq_lock, rq_guard)(tsk); @@ -8975,21 +8949,14 @@ void sched_move_task(struct task_struct =20 update_rq_clock(rq); =20 - running =3D task_current_donor(rq, tsk); - queued =3D task_on_rq_queued(tsk); + scoped_guard (sched_change, tsk, queue_flags) { + sched_change_group(tsk, group); + scx_move_task(tsk); + if (scope.running) + resched =3D true; + } =20 - if (queued) - dequeue_task(rq, tsk, queue_flags); - if (running) - put_prev_task(rq, tsk); - - sched_change_group(tsk, group); - scx_move_task(tsk); - - if (queued) - enqueue_task(rq, tsk, queue_flags); - if (running) { - set_next_task(rq, tsk); + if (resched) { /* * After changing group, the running task may have joined a * throttled one but it's still the running task. Trigger a @@ -10580,37 +10547,34 @@ void sched_mm_cid_fork(struct task_struc } #endif =20 -#ifdef CONFIG_SCHED_CLASS_EXT -void sched_deq_and_put_task(struct task_struct *p, int queue_flags, - struct sched_enq_and_set_ctx *ctx) +struct sched_change_ctx sched_change_begin(struct task_struct *p, unsigned= int flags) { struct rq *rq =3D task_rq(p); - - lockdep_assert_rq_held(rq); - - *ctx =3D (struct sched_enq_and_set_ctx){ + struct sched_change_ctx ctx =3D { .p =3D p, - .queue_flags =3D queue_flags, + .flags =3D flags, .queued =3D task_on_rq_queued(p), .running =3D task_current(rq, p), }; =20 - update_rq_clock(rq); - if (ctx->queued) - dequeue_task(rq, p, queue_flags | DEQUEUE_NOCLOCK); - if (ctx->running) + lockdep_assert_rq_held(rq); + + if (ctx.queued) + dequeue_task(rq, p, flags); + if (ctx.running) put_prev_task(rq, p); + + return ctx; } =20 -void sched_enq_and_set_task(struct sched_enq_and_set_ctx *ctx) +void sched_change_end(struct sched_change_ctx ctx) { - struct rq *rq =3D task_rq(ctx->p); + struct rq *rq =3D task_rq(ctx.p); =20 lockdep_assert_rq_held(rq); =20 - if (ctx->queued) - enqueue_task(rq, ctx->p, ctx->queue_flags | ENQUEUE_NOCLOCK); - if (ctx->running) - set_next_task(rq, ctx->p); + if (ctx.queued) + enqueue_task(rq, ctx.p, ctx.flags | ENQUEUE_NOCLOCK); + if (ctx.running) + set_next_task(rq, ctx.p); } -#endif /* CONFIG_SCHED_CLASS_EXT */ --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -4355,11 +4355,10 @@ static void scx_ops_bypass(bool bypass) */ list_for_each_entry_safe_reverse(p, n, &rq->scx.runnable_list, scx.runnable_node) { - struct sched_enq_and_set_ctx ctx; - /* cycling deq/enq is enough, see the function comment */ - sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx); - sched_enq_and_set_task(&ctx); + scoped_guard (sched_change, p, DEQUEUE_SAVE | DEQUEUE_MOVE) { + /* nothing */ ; + } } =20 rq_unlock_irqrestore(rq, &rf); @@ -4491,17 +4490,14 @@ static void scx_ops_disable_workfn(struc const struct sched_class *old_class =3D p->sched_class; const struct sched_class *new_class =3D __setscheduler_class(p->policy, p->prio); - struct sched_enq_and_set_ctx ctx; =20 if (old_class !=3D new_class && p->se.sched_delayed) dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED); =20 - sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx); - - p->sched_class =3D new_class; - check_class_changing(task_rq(p), p, old_class); - - sched_enq_and_set_task(&ctx); + scoped_guard (sched_change, p, DEQUEUE_SAVE | DEQUEUE_MOVE) { + p->sched_class =3D new_class; + check_class_changing(task_rq(p), p, old_class); + } =20 check_class_changed(task_rq(p), p, old_class, p->prio); scx_ops_exit_task(p); @@ -5206,18 +5202,15 @@ static int scx_ops_enable(struct sched_e const struct sched_class *old_class =3D p->sched_class; const struct sched_class *new_class =3D __setscheduler_class(p->policy, p->prio); - struct sched_enq_and_set_ctx ctx; =20 if (old_class !=3D new_class && p->se.sched_delayed) - dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEE_DELAYED); - - sched_deq_and_put_task(p, DEQUEUE_SAVE | DEQUEUE_MOVE, &ctx); - - p->scx.slice =3D SCX_SLICE_DFL; - p->sched_class =3D new_class; - check_class_changing(task_rq(p), p, old_class); + dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED); =20 - sched_enq_and_set_task(&ctx); + scoped_guard (sched_change, p, DEQUEUE_SAVE | DEQUEUE_MOVE) { + p->scx.slice =3D SCX_SLICE_DFL; + p->sched_class =3D new_class; + check_class_changing(task_rq(p), p, old_class); + } =20 check_class_changed(task_rq(p), p, old_class, p->prio); } --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -3921,23 +3921,22 @@ static inline void balance_callbacks(str =20 #endif =20 -#ifdef CONFIG_SCHED_CLASS_EXT -/* - * Used by SCX in the enable/disable paths to move tasks between sched_cla= sses - * and establish invariants. - */ -struct sched_enq_and_set_ctx { +struct sched_change_ctx { struct task_struct *p; - int queue_flags; + unsigned int flags; bool queued; bool running; }; =20 -void sched_deq_and_put_task(struct task_struct *p, int queue_flags, - struct sched_enq_and_set_ctx *ctx); -void sched_enq_and_set_task(struct sched_enq_and_set_ctx *ctx); +struct sched_change_ctx sched_change_begin(struct task_struct *p, unsigned= int flags); +void sched_change_end(struct sched_change_ctx ctx); =20 -#endif /* CONFIG_SCHED_CLASS_EXT */ +DEFINE_CLASS(sched_change, struct sched_change_ctx, + sched_change_end(_T), + sched_change_begin(p, flags), + struct task_struct *p, unsigned int flags) + +DEFINE_CLASS_IS_UNCONDITIONAL(sched_change) =20 #include "ext.h" =20 --- a/kernel/sched/syscalls.c +++ b/kernel/sched/syscalls.c @@ -64,7 +64,6 @@ static int effective_prio(struct task_st =20 void set_user_nice(struct task_struct *p, long nice) { - bool queued, running; struct rq *rq; int old_prio; =20 @@ -90,22 +89,12 @@ void set_user_nice(struct task_struct *p return; } =20 - queued =3D task_on_rq_queued(p); - running =3D task_current_donor(rq, p); - if (queued) - dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK); - if (running) - put_prev_task(rq, p); - - p->static_prio =3D NICE_TO_PRIO(nice); - set_load_weight(p, true); - old_prio =3D p->prio; - p->prio =3D effective_prio(p); - - if (queued) - enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK); - if (running) - set_next_task(rq, p); + scoped_guard (sched_change, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK) { + p->static_prio =3D NICE_TO_PRIO(nice); + set_load_weight(p, true); + old_prio =3D p->prio; + p->prio =3D effective_prio(p); + } =20 /* * If the task increased its priority or is running and @@ -528,7 +517,7 @@ int __sched_setscheduler(struct task_str bool user, bool pi) { int oldpolicy =3D -1, policy =3D attr->sched_policy; - int retval, oldprio, newprio, queued, running; + int retval, oldprio, newprio; const struct sched_class *prev_class, *next_class; struct balance_callback *head; struct rq_flags rf; @@ -712,33 +701,25 @@ int __sched_setscheduler(struct task_str if (prev_class !=3D next_class && p->se.sched_delayed) dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK); =20 - queued =3D task_on_rq_queued(p); - running =3D task_current_donor(rq, p); - if (queued) - dequeue_task(rq, p, queue_flags); - if (running) - put_prev_task(rq, p); - - if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) { - __setscheduler_params(p, attr); - p->sched_class =3D next_class; - p->prio =3D newprio; - } - __setscheduler_uclamp(p, attr); - check_class_changing(rq, p, prev_class); + scoped_guard (sched_change, p, queue_flags) { =20 - if (queued) { - /* - * We enqueue to tail when the priority of a task is - * increased (user space view). - */ - if (oldprio < p->prio) - queue_flags |=3D ENQUEUE_HEAD; + if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) { + __setscheduler_params(p, attr); + p->sched_class =3D next_class; + p->prio =3D newprio; + } + __setscheduler_uclamp(p, attr); + check_class_changing(rq, p, prev_class); =20 - enqueue_task(rq, p, queue_flags); + if (scope.queued) { + /* + * We enqueue to tail when the priority of a task is + * increased (user space view). + */ + if (oldprio < p->prio) + scope.flags |=3D ENQUEUE_HEAD; + } } - if (running) - set_next_task(rq, p); =20 check_class_changed(rq, p, prev_class, oldprio);