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ae7927023243dcc7389b2d59b16c09cbbeaecc36
linux/kernel
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Peter Zijlstra ae79270232 sched: Optimize finish_lock_switch() 
The kernel test robot measured a -1.6% performance regression on
will-it-scale/sched_yield due to commit:

  2558aacff8 ("sched/hotplug: Ensure only per-cpu kthreads run during hotplug")

Even though we were careful to replace a single load with another
single load from the same cacheline.

Restore finish_lock_switch() to the exact state before the offending
patch and solve the problem differently.

Fixes: 2558aacff8 ("sched/hotplug: Ensure only per-cpu kthreads run during hotplug")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201210161408.GX3021@hirez.programming.kicks-ass.net
2020-12-15 11:27:53 +01:00
..
bpf
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
cgroup
cpuset: fix race between hotplug work and later CPU offline
2020-11-19 11:25:45 +01:00
configs
…
debug
smp: Cleanup smp_call_function*()
2020-11-24 16:47:49 +01:00
dma
swiotlb: remove the tbl_dma_addr argument to swiotlb_tbl_map_single
2020-11-02 10:10:39 -05:00
entry
entry: Fix the incorrect ordering of lockdep and RCU check
2020-11-04 18:06:14 +01:00
events
perf: Tweak perf_event_attr::exclusive semantics
2020-11-09 18:12:36 +01:00
gcov
gcov: add support for GCC 10.1
2020-09-11 09:33:54 -07:00
irq
Merge tag 'irq-urgent-2020-11-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2020-11-08 09:52:57 -08:00
kcsan
kernel/: fix repeated words in comments
2020-10-16 11:11:19 -07:00
livepatch
kernel/: fix repeated words in comments
2020-10-16 11:11:19 -07:00
locking
lockdep: Put graph lock/unlock under lock_recursion protection
2020-11-17 13:15:35 +01:00
power
PM: sleep: fix typo in kernel/power/process.c
2020-10-27 19:11:44 +01:00
printk
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
rcu
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
sched
sched: Optimize finish_lock_switch()
2020-12-15 11:27:53 +01:00
time
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
trace
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
.gitignore
…
acct.c
kernel: acct.c: fix some kernel-doc nits
2020-10-16 11:11:19 -07:00
async.c
treewide: Remove uninitialized_var() usage
2020-07-16 12:35:15 -07:00
audit_fsnotify.c
fsnotify: create method handle_inode_event() in fsnotify_operations
2020-07-27 23:25:50 +02:00
audit_tree.c
Merge tag 'fsnotify_for_v5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
2020-08-06 19:29:51 -07:00
audit_watch.c
fsnotify: create method handle_inode_event() in fsnotify_operations
2020-07-27 23:25:50 +02:00
audit.c
audit: Remove redundant null check
2020-08-26 09:10:39 -04:00
audit.h
audit: change unnecessary globals into statics
2020-08-17 20:26:58 -04:00
auditfilter.c
treewide: Use fallthrough pseudo-keyword
2020-08-23 17:36:59 -05:00
auditsc.c
Merge tag 'audit-pr-20200803' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
2020-08-04 14:20:26 -07:00
backtracetest.c
treewide: Replace DECLARE_TASKLET() with DECLARE_TASKLET_OLD()
2020-07-30 11:15:58 -07:00
bounds.c
…
capability.c
LSM: Signal to SafeSetID when setting group IDs
2020-10-13 09:17:34 -07:00
compat.c
treewide: Use fallthrough pseudo-keyword
2020-08-23 17:36:59 -05:00
configs.c
…
context_tracking.c
context_tracking: Ensure that the critical path cannot be instrumented
2020-06-11 15:14:36 +02:00
cpu_pm.c
notifier: Fix broken error handling pattern
2020-09-01 09:58:03 +02:00
cpu.c
sched/hotplug: Consolidate task migration on CPU unplug
2020-11-10 18:38:58 +01:00
crash_core.c
kdump: append kernel build-id string to VMCOREINFO
2020-08-12 10:58:01 -07:00
crash_dump.c
…
cred.c
exec: Teach prepare_exec_creds how exec treats uids & gids
2020-05-20 14:44:21 -05:00
delayacct.c
…
dma.c
…
elfcore.c
…
exec_domain.c
…
exit.c
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
extable.c
…
fail_function.c
fail_function: Remove a redundant mutex unlock
2020-11-19 11:58:16 -08:00
fork.c
fork: fix copy_process(CLONE_PARENT) race with the exiting ->real_parent
2020-11-08 11:18:39 -08:00
freezer.c
…
futex.c
futex: Don't enable IRQs unconditionally in put_pi_state()
2020-11-09 14:30:30 +01:00
gen_kheaders.sh
kbuild: add variables for compression tools
2020-06-06 23:42:01 +09:00
groups.c
LSM: Signal to SafeSetID when setting group IDs
2020-10-13 09:17:34 -07:00
hung_task.c
kernel/hung_task.c: make type annotations consistent
2020-11-02 12:14:19 -08:00
iomem.c
…
irq_work.c
irq_work: Optimize irq_work_single()
2020-11-24 16:47:49 +01:00
jump_label.c
kernel/: fix repeated words in comments
2020-10-16 11:11:19 -07:00
kallsyms.c
treewide: Convert macro and uses of __section(foo) to __section("foo")
2020-10-25 14:51:49 -07:00
kcmp.c
…
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.locks
…
Kconfig.preempt
…
kcov.c
kcov: make some symbols static
2020-08-12 10:58:02 -07:00
kexec_core.c
kernel/: fix repeated words in comments
2020-10-16 11:11:19 -07:00
kexec_elf.c
…
kexec_file.c
kernel/resource: move and rename IORESOURCE_MEM_DRIVER_MANAGED
2020-10-16 11:11:18 -07:00
kexec_internal.h
…
kexec.c
LSM: Introduce kernel_post_load_data() hook
2020-10-05 13:37:03 +02:00
kheaders.c
…
kmod.c
kmod: remove redundant "be an" in the comment
2020-08-12 10:58:01 -07:00
kprobes.c
kprobes: Tell lockdep about kprobe nesting
2020-11-04 09:46:06 -05:00
ksysfs.c
…
kthread.c
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
latencytop.c
…
Makefile
Merge tag 'kbuild-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
2020-10-22 13:13:57 -07:00
module_signature.c
…
module_signing.c
…
module-internal.h
…
module.c
Merge tag 'modules-for-v5.10' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux
2020-10-22 13:08:57 -07:00
notifier.c
notifier: Fix broken error handling pattern
2020-09-01 09:58:03 +02:00
nsproxy.c
nsproxy: support CLONE_NEWTIME with setns()
2020-07-08 11:14:22 +02:00
padata.c
padata: fix possible padata_works_lock deadlock
2020-09-04 17:51:55 +10:00
panic.c
panic: don't dump stack twice on warn
2020-11-14 11:26:04 -08:00
params.c
params: Replace zero-length array with flexible-array member
2020-10-29 17:22:59 -05:00
pid_namespace.c
kernel/: fix repeated words in comments
2020-10-16 11:11:19 -07:00
pid.c
pid: move pidfd_get_pid() to pid.c
2020-10-18 09:27:10 -07:00
profile.c
…
ptrace.c
ptrace: Set PF_SUPERPRIV when checking capability
2020-11-17 12:53:22 -08:00
range.c
kernel.h: split out min()/max() et al. helpers
2020-10-16 11:11:19 -07:00
reboot.c
reboot: fix overflow parsing reboot cpu number
2020-11-14 11:26:03 -08:00
regset.c
regset: kill ->get()
2020-07-27 14:31:12 -04:00
relay.c
kernel/relay.c: drop unneeded initialization
2020-10-16 11:11:22 -07:00
resource.c
kernel/resource: make iomem_resource implicit in release_mem_region_adjustable()
2020-10-16 11:11:18 -07:00
rseq.c
…
scftorture.c
scftorture: Add cond_resched() to test loop
2020-08-24 18:38:38 -07:00
scs.c
mm: memcontrol: account kernel stack per node
2020-08-07 11:33:25 -07:00
seccomp.c
seccomp: Set PF_SUPERPRIV when checking capability
2020-11-17 12:53:22 -08:00
signal.c
ptrace: fix task_join_group_stop() for the case when current is traced
2020-11-02 12:14:19 -08:00
smp.c
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
smpboot.c
…
smpboot.h
…
softirq.c
softirq: Add debug check to __raise_softirq_irqoff()
2020-09-16 15:18:56 +02:00
stackleak.c
stackleak: let stack_erasing_sysctl take a kernel pointer buffer
2020-09-19 13:13:39 -07:00
stacktrace.c
stacktrace: Remove reliable argument from arch_stack_walk() callback
2020-09-18 14:24:16 +01:00
static_call.c
static_call: Fix return type of static_call_init
2020-10-02 21:18:25 +02:00
stop_machine.c
Merge branch 'linus' into sched/core, to resolve semantic conflict
2020-11-27 11:10:50 +01:00
sys_ni.c
mm/madvise: introduce process_madvise() syscall: an external memory hinting API
2020-10-18 09:27:10 -07:00
sys.c
kernel/sys.c: fix prototype of prctl_get_tid_address()
2020-10-25 11:44:16 -07:00
sysctl-test.c
…
sysctl.c
mm: allow a controlled amount of unfairness in the page lock
2020-09-17 10:26:41 -07:00
task_work.c
task_work: cleanup notification modes
2020-10-17 15:05:30 -06:00
taskstats.c
taskstats: move specifying netlink policy back to ops
2020-10-02 19:11:12 -07:00
test_kprobes.c
…
torture.c
torture: Dump ftrace at shutdown only if requested
2020-06-29 12:01:45 -07:00
tracepoint.c
tracepoint: Replace zero-length array with flexible-array member
2020-10-29 17:22:59 -05:00
tsacct.c
…
ucount.c
…
uid16.c
…
uid16.h
…
umh.c
usermodehelper: reset umask to default before executing user process
2020-10-06 10:31:52 -07:00
up.c
…
user_namespace.c
kernel/: fix repeated words in comments
2020-10-16 11:11:19 -07:00
user-return-notifier.c
…
user.c
user.c: make uidhash_table static
2020-06-04 19:06:24 -07:00
usermode_driver.c
umd: Stop using split_argv
2020-07-07 11:58:59 -05:00
utsname_sysctl.c
…
utsname.c
nsproxy: add struct nsset
2020-05-09 13:57:12 +02:00
watch_queue.c
watch_queue: Limit the number of watches a user can hold
2020-08-17 09:39:18 -07:00
watchdog_hld.c
…
watchdog.c
kernel/watchdog: fix watchdog_allowed_mask not used warning
2020-11-14 11:26:03 -08:00
workqueue_internal.h
…
workqueue.c
workqueue: Manually break affinity on hotplug
2020-11-10 18:38:58 +01:00