Merge tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:
 "Core scheduler changes:

   - Better tracking of maximum lag of tasks in presence of different
     slices duration, for better handling of lag in the fair scheduler
     (Vincent Guittot)

   - Clean up and standardize #if/#else/#endif markers throughout the
     entire scheduler code base (Ingo Molnar)

   - Make SMP unconditional: build the SMP scheduler's data structures
     and logic on UP kernel too, even though they are not used, to
     simplify the scheduler and remove around 200 #ifdef/[#else]/#endif
     blocks from the scheduler (Ingo Molnar)

   - Reorganize cgroup bandwidth control interface handling for better
     interfacing with sched_ext (Tejun Heo)

  Balancing:

   - Bump sd->max_newidle_lb_cost when newidle balance fails (Chris
     Mason)

   - Remove sched_domain_topology_level::flags to simplify the code
     (Prateek Nayak)

   - Simplify and clean up build_sched_topology() (Li Chen)

   - Optimize build_sched_topology() on large machines (Li Chen)

  Real-time scheduling:

   - Add initial version of proxy execution: a mechanism for
     mutex-owning tasks to inherit the scheduling context of higher
     priority waiters.

     Currently limited to a single runqueue and conditional on
     CONFIG_EXPERT, and other limitations (John Stultz, Peter Zijlstra,
     Valentin Schneider)

   - Deadline scheduler (Juri Lelli):
      - Fix dl_servers initialization order (Juri Lelli)
      - Fix DL scheduler's root domain reinitialization logic (Juri
        Lelli)
      - Fix accounting bugs after global limits change (Juri Lelli)
      - Fix scalability regression by implementing less agressive
        dl_server handling (Peter Zijlstra)

  PSI:

   - Improve scalability by optimizing psi_group_change() cpu_clock()
     usage (Peter Zijlstra)

  Rust changes:

   - Make Task, CondVar and PollCondVar methods inline to avoid
     unnecessary function calls (Kunwu Chan, Panagiotis Foliadis)

   - Add might_sleep() support for Rust code: Rust's "#[track_caller]"
     mechanism is used so that Rust's might_sleep() doesn't need to be
     defined as a macro (Fujita Tomonori)

   - Introduce file_from_location() (Boqun Feng)

  Debugging & instrumentation:

   - Make clangd usable with scheduler source code files again (Peter
     Zijlstra)

   - tools: Add root_domains_dump.py which dumps root domains info (Juri
     Lelli)

   - tools: Add dl_bw_dump.py for printing bandwidth accounting info
     (Juri Lelli)

  Misc cleanups & fixes:

   - Remove play_idle() (Feng Lee)

   - Fix check_preemption_disabled() (Sebastian Andrzej Siewior)

   - Do not call __put_task_struct() on RT if pi_blocked_on is set (Luis
     Claudio R. Goncalves)

   - Correct the comment in place_entity() (wang wei)"

* tag 'sched-core-2025-07-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (84 commits)
  sched/idle: Remove play_idle()
  sched: Do not call __put_task_struct() on rt if pi_blocked_on is set
  sched: Start blocked_on chain processing in find_proxy_task()
  sched: Fix proxy/current (push,pull)ability
  sched: Add an initial sketch of the find_proxy_task() function
  sched: Fix runtime accounting w/ split exec & sched contexts
  sched: Move update_curr_task logic into update_curr_se
  locking/mutex: Add p->blocked_on wrappers for correctness checks
  locking/mutex: Rework task_struct::blocked_on
  sched: Add CONFIG_SCHED_PROXY_EXEC & boot argument to enable/disable
  sched/topology: Remove sched_domain_topology_level::flags
  x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled
  x86/smpboot: moves x86_topology to static initialize and truncate
  x86/smpboot: remove redundant CONFIG_SCHED_SMT
  smpboot: introduce SDTL_INIT() helper to tidy sched topology setup
  tools/sched: Add dl_bw_dump.py for printing bandwidth accounting info
  tools/sched: Add root_domains_dump.py which dumps root domains info
  sched/deadline: Fix accounting after global limits change
  sched/deadline: Reset extra_bw to max_bw when clearing root domains
  sched/deadline: Initialize dl_servers after SMP
  ...

1 files changed, 68 insertions, 0 deletions

diff --git a/tools/sched/root_domains_dump.py b/tools/sched/root_domains_dump.py
new file mode 100644
index 0000000000000..56dc91f017b20
--- /dev/null
+++ b/tools/sched/root_domains_dump.py
@@ -0,0 +1,68 @@
+#!/usr/bin/env drgn
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2025 Juri Lelli <juri.lelli@redhat.com>
+# Copyright (C) 2025 Red Hat, Inc.
+
+desc = """
+This is a drgn script to show the current root domains configuration. For more
+info on drgn, visit https://github.com/osandov/drgn.
+
+Root domains are only printed once, as multiple CPUs might be attached to the
+same root domain.
+"""
+
+import os
+import argparse
+
+import drgn
+from drgn import FaultError
+from drgn.helpers.common import *
+from drgn.helpers.linux import *
+
+def print_root_domains_info():
+
+    # To store unique root domains found
+    seen_root_domains = set()
+
+    print("Retrieving (unique) Root Domain Information:")
+
+    runqueues = prog['runqueues']
+    def_root_domain = prog['def_root_domain']
+
+    for cpu_id in for_each_possible_cpu(prog):
+        try:
+            rq = per_cpu(runqueues, cpu_id)
+
+            root_domain = rq.rd
+
+            # Check if we've already processed this root domain to avoid duplicates
+            # Use the memory address of the root_domain as a unique identifier
+            root_domain_cast = int(root_domain)
+            if root_domain_cast in seen_root_domains:
+                continue
+            seen_root_domains.add(root_domain_cast)
+
+            if root_domain_cast == int(def_root_domain.address_):
+                print(f"\n--- Root Domain @ def_root_domain ---")
+            else:
+                print(f"\n--- Root Domain @ 0x{root_domain_cast:x} ---")
+
+            print(f"  From CPU: {cpu_id}") # This CPU belongs to this root domain
+
+            # Access and print relevant fields from struct root_domain
+            print(f"  Span       : {cpumask_to_cpulist(root_domain.span[0])}")
+            print(f"  Online     : {cpumask_to_cpulist(root_domain.span[0])}")
+
+        except drgn.FaultError as fe:
+            print(f"  (CPU {cpu_id}: Fault accessing kernel memory: {fe})")
+        except AttributeError as ae:
+            print(f"  (CPU {cpu_id}: Missing attribute for root_domain (kernel struct change?): {ae})")
+        except Exception as e:
+            print(f"  (CPU {cpu_id}: An unexpected error occurred: {e})")
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description=desc,
+                                     formatter_class=argparse.RawTextHelpFormatter)
+    args = parser.parse_args()
+
+    print_root_domains_info()