Merge tag 'sched-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - The biggest change is introduction of a new iteration of the
   SCHED_FAIR interactivity code: the EEVDF ("Earliest Eligible Virtual
   Deadline First") scheduler

   EEVDF too is a virtual-time scheduler, with two parameters (weight
   and relative deadline), compared to CFS that had weight only. It
   completely reworks the base scheduler: placement, preemption, picking
   -- everything

   LWN.net, as usual, has a terrific writeup about EEVDF:

      https://lwn.net/Articles/925371/

   Preemption (both tick and wakeup) is driven by testing against a
   fresh pick. Because the tree is now effectively an interval tree, and
   the selection is no longer the 'leftmost' task, over-scheduling is
   less of a problem. A lot of the CFS heuristics are removed or
   replaced by more natural latency-space parameters & constructs

   In terms of expected performance regressions: we will and can fix
   everything where a 'good' workload misbehaves with the new scheduler,
   but EEVDF inevitably changes workload scheduling in a binary fashion,
   hopefully for the better in the overwhelming majority of cases, but
   in some cases it won't, especially in adversarial loads that got
   lucky with the previous code, such as some variants of hackbench. We
   are trying hard to err on the side of fixing all performance
   regressions, but we expect some inevitable post-release iterations of
   that process

 - Improve load-balancing on hybrid x86 systems: enable cluster
   scheduling (again)

 - Improve & fix bandwidth-scheduling on nohz systems

 - Improve bandwidth-throttling

 - Use lock guards to simplify and de-goto-ify control flow

 - Misc improvements, cleanups and fixes

* tag 'sched-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (43 commits)
  sched/eevdf/doc: Modify the documented knob to base_slice_ns as well
  sched/eevdf: Curb wakeup-preemption
  sched: Simplify sched_core_cpu_{starting,deactivate}()
  sched: Simplify try_steal_cookie()
  sched: Simplify sched_tick_remote()
  sched: Simplify sched_exec()
  sched: Simplify ttwu()
  sched: Simplify wake_up_if_idle()
  sched: Simplify: migrate_swap_stop()
  sched: Simplify sysctl_sched_uclamp_handler()
  sched: Simplify get_nohz_timer_target()
  sched/rt: sysctl_sched_rr_timeslice show default timeslice after reset
  sched/rt: Fix sysctl_sched_rr_timeslice intial value
  sched/fair: Block nohz tick_stop when cfs bandwidth in use
  sched, cgroup: Restore meaning to hierarchical_quota
  MAINTAINERS: Add Peter explicitly to the psi section
  sched/psi: Select KERNFS as needed
  sched/topology: Align group flags when removing degenerate domain
  sched/fair: remove util_est boosting
  sched/fair: Propagate enqueue flags into place_entity()
  ...

1 files changed, 1 insertions, 0 deletions

diff --git a/init/Kconfig b/init/Kconfig
index f7f65af4ee12..5e7d4885d1bf 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -629,6 +629,7 @@ config TASK_IO_ACCOUNTING
 
 config PSI
 	bool "Pressure stall information tracking"
+	select KERNFS
 	help
 	  Collect metrics that indicate how overcommitted the CPU, memory,
 	  and IO capacity are in the system.