From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu, 19 Sep 2024 13:55:58 +0000 (+0200)
Subject: Merge tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git... 
X-Git-Tag: v6.12-rc1~120
X-Git-Url: https://repo.jachan.dev/linux.git/commitdiff_plain/2004cef11ea072838f99bd95cefa5c8e45df0847

Merge tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Implement the SCHED_DEADLINE server infrastructure - Daniel Bristot
   de Oliveira's last major contribution to the kernel:

     "SCHED_DEADLINE servers can help fixing starvation issues of low
      priority tasks (e.g., SCHED_OTHER) when higher priority tasks
      monopolize CPU cycles. Today we have RT Throttling; DEADLINE
      servers should be able to replace and improve that."

   (Daniel Bristot de Oliveira, Peter Zijlstra, Joel Fernandes, Youssef
   Esmat, Huang Shijie)

 - Preparatory changes for sched_ext integration:
     - Use set_next_task(.first) where required
     - Fix up set_next_task() implementations
     - Clean up DL server vs. core sched
     - Split up put_prev_task_balance()
     - Rework pick_next_task()
     - Combine the last put_prev_task() and the first set_next_task()
     - Rework dl_server
     - Add put_prev_task(.next)

   (Peter Zijlstra, with a fix by Tejun Heo)

 - Complete the EEVDF transition and refine EEVDF scheduling:
     - Implement delayed dequeue
     - Allow shorter slices to wakeup-preempt
     - Use sched_attr::sched_runtime to set request/slice suggestion
     - Document the new feature flags
     - Remove unused and duplicate-functionality fields
     - Simplify & unify pick_next_task_fair()
     - Misc debuggability enhancements

   (Peter Zijlstra, with fixes/cleanups by Dietmar Eggemann, Valentin
   Schneider and Chuyi Zhou)

 - Initialize the vruntime of a new task when it is first enqueued,
   resulting in significant decrease in latency of newly woken tasks
   (Zhang Qiao)

 - Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
   (K Prateek Nayak, Peter Zijlstra)

 - Clean up and clarify the usage of Clean up usage of rt_task()
   (Qais Yousef)

 - Preempt SCHED_IDLE entities in strict cgroup hierarchies
   (Tianchen Ding)

 - Clarify the documentation of time units for deadline scheduler
   parameters (Christian Loehle)

 - Remove the HZ_BW chicken-bit feature flag introduced a year ago,
   the original change seems to be working fine (Phil Auld)

 - Misc fixes and cleanups (Chen Yu, Dan Carpenter, Huang Shijie,
   Peilin He, Qais Yousefm and Vincent Guittot)

* tag 'sched-core-2024-09-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits)
  sched/cpufreq: Use NSEC_PER_MSEC for deadline task
  cpufreq/cppc: Use NSEC_PER_MSEC for deadline task
  sched/deadline: Clarify nanoseconds in uapi
  sched/deadline: Convert schedtool example to chrt
  sched/debug: Fix the runnable tasks output
  sched: Fix sched_delayed vs sched_core
  kernel/sched: Fix util_est accounting for DELAY_DEQUEUE
  kthread: Fix task state in kthread worker if being frozen
  sched/pelt: Use rq_clock_task() for hw_pressure
  sched/fair: Move effective_cpu_util() and effective_cpu_util() in fair.c
  sched/core: Introduce SM_IDLE and an idle re-entry fast-path in __schedule()
  sched: Add put_prev_task(.next)
  sched: Rework dl_server
  sched: Combine the last put_prev_task() and the first set_next_task()
  sched: Rework pick_next_task()
  sched: Split up put_prev_task_balance()
  sched: Clean up DL server vs core sched
  sched: Fixup set_next_task() implementations
  sched: Use set_next_task(.first) where required
  sched/fair: Properly deactivate sched_delayed task upon class change
  ...
---

2004cef11ea072838f99bd95cefa5c8e45df0847
diff --cc fs/proc/base.c
index e7810f3bd522,72a1acd03675..b31283d81c52
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@@ -2626,11 -2569,10 +2626,11 @@@ static ssize_t timerslack_ns_write(stru
  	}
  
  	task_lock(p);
- 	if (task_is_realtime(p))
 -	if (slack_ns == 0)
 -		p->timer_slack_ns = p->default_timer_slack_ns;
 -	else
 -		p->timer_slack_ns = slack_ns;
++	if (rt_or_dl_task_policy(p))
 +		slack_ns = 0;
 +	else if (slack_ns == 0)
 +		slack_ns = p->default_timer_slack_ns;
 +	p->timer_slack_ns = slack_ns;
  	task_unlock(p);
  
  out:
diff --cc kernel/sched/syscalls.c
index 195d2f2834a9,c62acf509b74..cb03c790c27a
--- a/kernel/sched/syscalls.c
+++ b/kernel/sched/syscalls.c
@@@ -401,19 -300,21 +300,29 @@@ static void __setscheduler_params(struc
  
  	p->policy = policy;
  
- 	if (dl_policy(policy))
+ 	if (dl_policy(policy)) {
  		__setparam_dl(p, attr);
- 	else if (fair_policy(policy))
+ 	} else if (fair_policy(policy)) {
  		p->static_prio = NICE_TO_PRIO(attr->sched_nice);
+ 		if (attr->sched_runtime) {
+ 			p->se.custom_slice = 1;
+ 			p->se.slice = clamp_t(u64, attr->sched_runtime,
+ 					      NSEC_PER_MSEC/10,   /* HZ=1000 * 10 */
+ 					      NSEC_PER_MSEC*100); /* HZ=100  / 10 */
+ 		} else {
+ 			p->se.custom_slice = 0;
+ 			p->se.slice = sysctl_sched_base_slice;
+ 		}
+ 	}
  
 +	/* rt-policy tasks do not have a timerslack */
- 	if (task_is_realtime(p)) {
++	if (rt_or_dl_task_policy(p)) {
 +		p->timer_slack_ns = 0;
 +	} else if (p->timer_slack_ns == 0) {
 +		/* when switching back to non-rt policy, restore timerslack */
 +		p->timer_slack_ns = p->default_timer_slack_ns;
 +	}
 +
  	/*
  	 * __sched_setscheduler() ensures attr->sched_priority == 0 when
  	 * !rt_policy. Always setting this ensures that things like
diff --cc kernel/sys.c
index e3c4cffb520c,3a2df1bd9f64..b7e096e1c3a1
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@@ -2557,8 -2557,6 +2557,8 @@@ SYSCALL_DEFINE5(prctl, int, option, uns
  			error = current->timer_slack_ns;
  		break;
  	case PR_SET_TIMERSLACK:
- 		if (task_is_realtime(current))
++		if (rt_or_dl_task_policy(current))
 +			break;
  		if (arg2 <= 0)
  			current->timer_slack_ns =
  					current->default_timer_slack_ns;