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9fdb12c88e
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: Juri Lelli <juri.lelli@redhat.com> Signed-off-by: Peter 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
69 lines
2.3 KiB
Python
69 lines
2.3 KiB
Python
#!/usr/bin/env drgn
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# SPDX-License-Identifier: GPL-2.0
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# Copyright (C) 2025 Juri Lelli <juri.lelli@redhat.com>
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# Copyright (C) 2025 Red Hat, Inc.
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desc = """
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This is a drgn script to show the current root domains configuration. For more
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info on drgn, visit https://github.com/osandov/drgn.
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Root domains are only printed once, as multiple CPUs might be attached to the
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same root domain.
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"""
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import os
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import argparse
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import drgn
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from drgn import FaultError
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from drgn.helpers.common import *
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from drgn.helpers.linux import *
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def print_root_domains_info():
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# To store unique root domains found
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seen_root_domains = set()
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print("Retrieving (unique) Root Domain Information:")
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runqueues = prog['runqueues']
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def_root_domain = prog['def_root_domain']
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for cpu_id in for_each_possible_cpu(prog):
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try:
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rq = per_cpu(runqueues, cpu_id)
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root_domain = rq.rd
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# Check if we've already processed this root domain to avoid duplicates
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# Use the memory address of the root_domain as a unique identifier
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root_domain_cast = int(root_domain)
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if root_domain_cast in seen_root_domains:
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continue
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seen_root_domains.add(root_domain_cast)
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if root_domain_cast == int(def_root_domain.address_):
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print(f"\n--- Root Domain @ def_root_domain ---")
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else:
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print(f"\n--- Root Domain @ 0x{root_domain_cast:x} ---")
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print(f" From CPU: {cpu_id}") # This CPU belongs to this root domain
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# Access and print relevant fields from struct root_domain
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print(f" Span : {cpumask_to_cpulist(root_domain.span[0])}")
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print(f" Online : {cpumask_to_cpulist(root_domain.span[0])}")
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except drgn.FaultError as fe:
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print(f" (CPU {cpu_id}: Fault accessing kernel memory: {fe})")
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except AttributeError as ae:
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print(f" (CPU {cpu_id}: Missing attribute for root_domain (kernel struct change?): {ae})")
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except Exception as e:
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print(f" (CPU {cpu_id}: An unexpected error occurred: {e})")
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if __name__ == "__main__":
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parser = argparse.ArgumentParser(description=desc,
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formatter_class=argparse.RawTextHelpFormatter)
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args = parser.parse_args()
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print_root_domains_info()
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