Commit 9fdb12c8 authored by Juri Lelli's avatar Juri Lelli Committed by Peter Zijlstra
Browse files

tools/sched: Add root_domains_dump.py which dumps root domains info 



Root domains information is somewhat hard to access at runtime. Even
with sched_debug and sched_verbose, such information is only printed
on kernel console when domains are modified.

Add a simple drgn script to more easily retrieve root domains
information at runtime.

Since tools/sched is a new directory, add it to MAINTAINERS as well.

Signed-off-by: default avatarJuri Lelli <juri.lelli@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Marcel Ziswiler <marcel.ziswiler@codethink.co.uk> # nuc & rock5b
Link: https://lore.kernel.org/r/20250627115118.438797-5-juri.lelli@redhat.com
parent 440989c1

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -22165,6 +22165,7 @@ F: include/linux/wait.h 
F:	include/uapi/linux/sched.h

F:	kernel/fork.c

F:	kernel/sched/

F:	tools/sched/









SCHEDULER - SCHED_EXT









R:	Tejun Heo <tj@kernel.org>

























tools/sched/root_domains_dump.py
0 → 100644



+68
−0






























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#!/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()