mirror-linux/kernel
Ilias Stamatis 6fb3acdebf Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()"
Commit 97523a4edb ("kernel/resource: remove first_lvl / siblings_only
logic") removed an optimization introduced by commit 756398750e
("resource: avoid unnecessary lookups in find_next_iomem_res()").  That
was not called out in the message of the first commit explicitly so it's
not entirely clear whether removing the optimization happened
inadvertently or not.

As the original commit message of the optimization explains there is no
point considering the children of a subtree in find_next_iomem_res() if
the top level range does not match.

Reinstating the optimization results in performance improvements in
systems where /proc/iomem is ~5k lines long.  Calling mmap() on /dev/mem
in such platforms takes 700-1500μs without the optimisation and 10-50μs
with the optimisation.

Note that even though commit 97523a4edb removed the 'sibling_only'
parameter from next_resource(), newer kernels have basically reinstated it
under the name 'skip_children'.

Link: https://lore.kernel.org/all/20251124165349.3377826-1-ilstam@amazon.com/T/#u
Fixes: 97523a4edb ("kernel/resource: remove first_lvl / siblings_only logic")
Signed-off-by: Ilias Stamatis <ilstam@amazon.com>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: "Huang, Ying" <huang.ying.caritas@gmail.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-27 14:24:45 -08:00
..
bpf bpf: Conditionally include dynptr copy kfuncs 2025-10-24 09:44:47 -07:00
cgroup cgroup: Fixes for v6.18-rc2 2025-10-20 09:41:27 -10:00
configs hung_task: panic when there are more than N hung tasks at the same time 2025-11-12 10:00:14 -08:00
debug kdb: remove redundant check for scancode 0xe0 2025-09-20 21:19:09 +01:00
dma dma-debug: don't report false positives with DMA_BOUNCE_UNALIGNED_KMALLOC 2025-10-15 13:24:33 -07:00
entry hyperv-next for v6.18 2025-10-07 08:40:15 -07:00
events perf/core: Fix system hang caused by cpu-clock usage 2025-11-03 11:04:19 +01:00
futex futex: Optimize per-cpu reference counting 2025-11-06 12:30:54 +01:00
gcov gcov: add support for GCC 15 2025-11-09 21:19:44 -08:00
irq genirq/manage: Add buslock back in to enable_irq() 2025-10-24 11:38:39 +02:00
kcsan Kernel Concurrency Sanitizer (KCSAN) updates for v6.18 2025-10-02 08:31:44 -07:00
livepatch sched,livepatch: Untangle cond_resched() and live-patching 2025-05-14 13:16:24 +02:00
liveupdate kho: fix restoring of contiguous ranges of order-0 pages 2025-11-27 14:24:44 -08:00
locking locking/local_lock: Introduce local_lock_is_locked(). 2025-09-29 09:42:35 +02:00
module taint/module: remove unnecessary taint_flag.module field 2025-11-12 10:00:15 -08:00
power PM: sleep: Allow pm_restrict_gfp_mask() stacking 2025-10-29 18:55:32 +01:00
printk printk changes for 6.18 2025-10-04 11:13:11 -07:00
rcu hyperv-next for v6.18 2025-10-07 08:40:15 -07:00
sched sched/fair: Prevent cfs_rq from being unthrottled with zero runtime_remaining 2025-11-06 12:30:52 +01:00
time timekeeping: Fix aux clocks sysfs initialization loop bound 2025-10-20 19:56:12 +02:00
trace Fixes for tracing: 2025-11-07 08:07:11 -08:00
unwind unwind: Finish up unwind when a task exits 2025-07-31 10:20:11 -04:00
.gitignore kheaders: rebuild kheaders_data.tar.xz when a file is modified within a minute 2025-06-24 20:30:37 +09:00
Kconfig.freezer
Kconfig.hz kernel: Fix "select" wording on HZ_250 description 2025-02-21 09:20:30 +01:00
Kconfig.kexec liveupdate: kho: move to kernel/liveupdate 2025-11-27 14:24:33 -08:00
Kconfig.locks
Kconfig.preempt softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT 2025-09-17 16:25:41 +02:00
Makefile liveupdate: kho: move to kernel/liveupdate 2025-11-27 14:24:33 -08:00
acct.c kernel/acct.c: saner struct file treatment 2025-09-27 20:13:56 -04:00
async.c
audit.c audit: fix skb leak when audit rate limit is exceeded 2025-09-10 19:55:00 -04:00
audit.h audit: create audit_stamp structure 2025-08-30 10:15:28 -04:00
audit_fsnotify.c VFS/audit: introduce kern_path_parent() for audit 2025-09-23 12:37:35 +02:00
audit_tree.c mount-related stuff for this cycle 2025-10-03 10:19:44 -07:00
audit_watch.c VFS/audit: introduce kern_path_parent() for audit 2025-09-23 12:37:35 +02:00
auditfilter.c audit/stable-6.18 PR 20250926 2025-09-30 08:22:16 -07:00
auditsc.c audit: add record for multiple object contexts 2025-08-30 10:15:30 -04:00
backtracetest.c
bounds.c
capability.c capability: Remove unused has_capability 2025-03-07 22:03:09 -06:00
cfi.c cfi: Move BPF CFI types and helpers to generic code 2025-07-31 18:23:53 -07:00
compat.c
configs.c
context_tracking.c context_tracking: Make RCU watch ct_kernel_exit_state() warning 2025-03-04 18:44:29 -08:00
cpu.c cpu: Remove obsolete comment from takedown_cpu() 2025-08-06 22:48:12 +02:00
cpu_pm.c
crash_core.c crash: fix crashkernel resource shrink 2025-11-15 10:52:01 -08:00
crash_core_test.c crash: add KUnit tests for crash_exclude_mem_range 2025-09-13 17:32:55 -07:00
crash_dump_dm_crypt.c crash_dump: retrieve dm crypt keys in kdump kernel 2025-05-21 10:48:21 -07:00
crash_reserve.c crash: let architecture decide crash memory export to iomem_resource 2025-11-12 10:00:15 -08:00
cred.c copy_process: pass clone_flags as u64 across calltree 2025-09-01 15:31:34 +02:00
delayacct.c delayacct: remove redundant code and adjust indentation 2025-05-27 19:40:33 -07:00
dma.c
elfcorehdr.c
exec_domain.c
exit.c release_task: kill unnecessary rcu_read_lock() around dec_rlimit_ucounts() 2025-11-12 10:00:17 -08:00
exit.h
extable.c
fail_function.c
fork.c fork: stop ignoring NUMA while handling cached thread stacks 2025-11-27 14:24:31 -08:00
freezer.c mm/oom_kill: thaw the entire OOM victim process 2025-09-21 14:22:35 -07:00
gen_kheaders.sh kheaders: make it possible to override TAR 2025-08-06 10:23:36 +09:00
groups.c
hung_task.c hung_task: add hung_task_sys_info sysctl to dump sys info on task-hung 2025-11-20 14:03:43 -08:00
iomem.c mm/memremap: Pass down MEMREMAP_* flags to arch_memremap_wb() 2025-02-21 15:05:38 +01:00
irq_work.c
jump_label.c jump_label: Use RCU in all users of __module_text_address(). 2025-03-10 11:54:46 +01:00
kallsyms.c bpf: Clean up individual BTF_ID code 2025-07-16 18:34:42 -07:00
kallsyms_internal.h
kallsyms_selftest.c kallsyms: use kmalloc_array() instead of kmalloc() 2025-09-28 11:36:14 -07:00
kallsyms_selftest.h
kcmp.c kcmp: improve performance adding an unlikely hint to task comparisons 2025-02-21 10:25:33 +01:00
kcov.c kcov: use write memory barrier after memcpy() in kcov_move_area() 2025-09-13 17:32:44 -07:00
kexec.c kexec: enable CMA based contiguous allocation 2025-08-02 12:01:38 -07:00
kexec_core.c kexec: move sysfs entries to /sys/kernel/kexec 2025-11-27 14:24:42 -08:00
kexec_elf.c kexec: initialize ELF lowest address to ULONG_MAX 2025-03-16 22:30:47 -07:00
kexec_file.c x86/kexec: carry forward the boot DTB on kexec 2025-09-13 17:32:43 -07:00
kexec_internal.h kexec: enable CMA based contiguous allocation 2025-08-02 12:01:38 -07:00
kheaders.c
kprobes.c kprobes: Add missing kerneldoc for __get_insn_slot 2025-07-15 18:45:34 +09:00
kstack_erase.c stackleak: Rename stackleak_track_stack to __sanitizer_cov_stack_depth 2025-07-21 21:40:39 -07:00
ksyms_common.c
ksysfs.c kexec: move sysfs entries to /sys/kernel/kexec 2025-11-27 14:24:42 -08:00
kthread.c ipvs: Fix estimator kthreads preferred affinity 2025-08-13 08:34:33 +02:00
latencytop.c
module_signature.c
notifier.c
nscommon.c ns: drop assert 2025-09-25 09:23:54 +02:00
nsproxy.c namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
nstree.c ns: move ns type into struct ns_common 2025-09-25 09:23:54 +02:00
padata.c padata: WQ_PERCPU added to alloc_workqueue users 2025-09-13 12:11:06 +08:00
panic.c panic: sys_info: align constant definition names with parameters 2025-11-20 14:03:40 -08:00
params.c params: Replace deprecated strcpy() with strscpy() and memcpy() 2025-08-16 21:47:25 +02:00
pid.c namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
pid_namespace.c namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
pid_sysctl.h
profile.c
ptrace.c ptrace: introduce PTRACE_SET_SYSCALL_INFO request 2025-05-11 17:48:15 -07:00
range.c
reboot.c - The 7 patch series "powerpc/crash: use generic crashkernel 2025-04-01 10:06:52 -07:00
regset.c
relay.c relayfs: support a counter tracking if data is too big to write 2025-07-09 22:57:52 -07:00
resource.c Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()" 2025-11-27 14:24:45 -08:00
resource_kunit.c
rseq.c rseq: Protect event mask against membarrier IPI 2025-09-13 19:51:59 +02:00
scftorture.c
scs.c scs: fix a wrong parameter in __scs_magic 2025-11-12 10:00:13 -08:00
seccomp.c Performance events updates for v6.18: 2025-09-30 11:11:21 -07:00
signal.c signal: Fix memory leak for PIDFD_SELF* sentinels 2025-08-19 13:51:28 +02:00
smp.c smp: Fix up and expand the smp_call_function_many() kerneldoc 2025-09-18 22:21:28 +02:00
smpboot.c sched/smp: Use the SMP version of idle_thread_set_boot_cpu() 2025-06-13 08:47:20 +02:00
smpboot.h
softirq.c softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT 2025-09-17 16:25:41 +02:00
stacktrace.c
static_call.c
static_call_inline.c Modules changes for 6.15-rc1 2025-03-30 15:44:36 -07:00
stop_machine.c sched/core: Fix migrate_swap() vs. hotplug 2025-07-01 15:02:03 +02:00
sys.c Patch series in this pull request: 2025-10-02 18:44:54 -07:00
sys_ni.c uprobes/x86: Add uprobe syscall to speed up uprobe 2025-08-21 20:09:20 +02:00
sysctl-test.c sysctl: move u8 register test to lib/test_sysctl.c 2025-04-14 14:13:41 +02:00
sysctl.c sysctl: rename kern_table -> sysctl_subsys_table 2025-07-23 11:56:02 +02:00
task_work.c
taskstats.c
torture.c torture: Delay CPU-hotplug operations until boot completes 2025-08-14 15:26:30 -07:00
tracepoint.c tracepoint: Print the function symbol when tracepoint_debug is set 2025-03-21 15:30:10 -04:00
tsacct.c pid: change bacct_add_tsk() to use task_ppid_nr_ns() 2025-08-19 13:38:20 +02:00
ucount.c ucount: use atomic_long_try_cmpxchg() in atomic_long_inc_below() 2025-08-02 12:01:38 -07:00
uid16.c
uid16.h
umh.c
up.c
user-return-notifier.c
user.c ns: move ns type into struct ns_common 2025-09-25 09:23:54 +02:00
user_namespace.c ns: move ns type into struct ns_common 2025-09-25 09:23:54 +02:00
utsname.c namespace-6.18-rc1 2025-09-29 11:20:29 -07:00
utsname_sysctl.c
vhost_task.c vhost: Take a reference on the task in struct vhost_task. 2025-09-21 17:44:20 -04:00
vmcore_info.c vmcoreinfo: track and log recoverable hardware errors 2025-11-27 14:24:44 -08:00
watch_queue.c vfs-6.15-rc1.pipe 2025-03-24 09:52:37 -07:00
watchdog.c watchdog: add sys_info sysctls to dump sys info on system lockup 2025-11-20 14:03:43 -08:00
watchdog_buddy.c watchdog: fix opencoded cpumask_next_wrap() in watchdog_next_cpu() 2025-07-31 11:28:03 -04:00
watchdog_perf.c watchdog: skip checks when panic is in progress 2025-09-13 17:32:53 -07:00
workqueue.c workqueue: WQ_PERCPU added to alloc_workqueue users 2025-09-16 10:33:53 -10:00
workqueue_internal.h