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43b3f02899f74ae9914a39547cc5492156f0027a
linux/kernel
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Peter Zijlstra 43b3f02899 locking/qspinlock/x86: Fix performance regression under unaccelerated VMs 
Dave ran into horrible performance on a VM without PARAVIRT_SPINLOCKS
set and Linus noted that the test-and-set implementation was retarded.

One should spin on the variable with a load, not a RMW.

While there, remove 'queued' from the name, as the lock isn't queued
at all, but a simple test-and-set.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Dave Chinner <david@fromorbit.com>
Tested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <Waiman.Long@hp.com>
Cc: stable@vger.kernel.org # v4.2+
Link: http://lkml.kernel.org/r/20150904152523.GR18673@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2015-09-11 07:49:42 +02:00
..
bpf
bpf: allow networking programs to use bpf_trace_printk() for debugging
2015-06-15 15:53:50 -07:00
configs
kconfig: add xenconfig defconfig helper
2015-06-16 11:04:29 +01:00
debug
debug: prevent entering debug mode on panic/exception.
2015-02-19 12:39:03 -06:00
events
perf: Fix AUX buffer refcounting
2015-07-06 14:08:30 +02:00
gcov
gcov: add support for GCC 5.1
2015-06-30 19:44:57 -07:00
irq
genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD
2015-07-17 11:29:34 +02:00
livepatch
Merge branches 'for-4.1/upstream-fixes', 'for-4.2/kaslr' and 'for-4.2/upstream' into for-linus
2015-06-22 16:26:56 +02:00
locking
locking/qspinlock/x86: Fix performance regression under unaccelerated VMs
2015-09-11 07:49:42 +02:00
power
Merge tag 'pm+acpi-4.2-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
2015-07-01 14:17:44 -07:00
printk
printk: improve the description of /dev/kmsg line format
2015-06-30 19:44:59 -07:00
rcu
Merge tag 'trace-v4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
2015-06-26 14:02:43 -07:00
sched
locking/static_keys: Add static_key_{en,dis}able() helpers
2015-08-03 11:34:14 +02:00
time
tick: Move the export of tick_broadcast_oneshot_control to the proper place
2015-07-14 12:01:04 +02:00
trace
ftrace: Fix breakage of set_ftrace_pid
2015-07-24 13:58:14 -04:00
.gitignore
…
acct.c
acct: check FMODE_CAN_WRITE
2015-04-11 22:27:55 -04:00
async.c
…
audit_tree.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2015-04-26 17:22:07 -07:00
audit_watch.c
VFS: audit: d_backing_inode() annotations
2015-04-15 15:06:55 -04:00
audit.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-06-27 13:53:16 -07:00
audit.h
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-04-22 14:49:23 -07:00
auditfilter.c
Merge branch 'upstream' of git://git.infradead.org/users/pcmoore/audit
2015-02-11 20:07:47 -08:00
auditsc.c
Fix broken audit tests for exec arg len
2015-07-08 09:33:38 -07:00
backtracetest.c
…
bounds.c
…
capability.c
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
cgroup_freezer.c
…
cgroup.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2015-07-03 15:20:57 -07:00
compat.c
compat: cleanup coding in compat_get_bitmap() and compat_put_bitmap()
2015-06-04 23:57:18 +02:00
configs.c
…
context_tracking.c
context_tracking: Inherit TIF_NOHZ through forks instead of context switches
2015-05-07 12:02:51 +02:00
cpu_pm.c
…
cpu.c
genirq: Revert sparse irq locking around __cpu_up() and move it to x86 for now
2015-07-15 10:39:17 +02:00
cpuset.c
kernel, cpuset: remove exception for __GFP_THISNODE
2015-04-14 16:49:03 -07:00
crash_dump.c
…
cred.c
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
delayacct.c
…
dma.c
…
elfcore.c
…
exec_domain.c
Remove rest of exec domains.
2015-04-12 21:03:31 +02:00
exit.c
exit,stats: /* obey this comment */
2015-06-25 17:00:43 -07:00
extable.c
ftrace/x86/extable: Add is_ftrace_trampoline() function
2014-11-19 15:25:26 -05:00
fork.c
x86/fpu, sched: Introduce CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT and use it on x86
2015-07-18 03:42:51 +02:00
freezer.c
freezer: remove obsolete comments in __thaw_task()
2014-10-21 23:44:20 +02:00
futex_compat.c
…
futex.c
futex: Make should_fail_futex() static
2015-07-20 21:43:54 +02:00
groups.c
kernel: conditionally support non-root users, groups and capabilities
2015-04-15 16:35:22 -07:00
hung_task.c
kernel/hung_task.c: change hung_task.c to use for_each_process_thread()
2015-04-15 16:35:22 -07:00
irq_work.c
percpu: Convert remaining __get_cpu_var uses in 3.18-rcX
2014-10-29 11:18:18 -04:00
jump_label.c
locking/static_keys: Add selftest
2015-08-03 11:34:16 +02:00
kallsyms.c
…
kcmp.c
…
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.locks
locking/qrwlock: Rename QUEUE_RWLOCK to QUEUED_RWLOCKS
2015-05-12 09:46:00 +02:00
Kconfig.preempt
…
kexec.c
kernel/panic/kexec: fix "crash_kexec_post_notifiers" option issue in oops path
2015-06-30 19:44:57 -07:00
kmod.c
usermodehelper: kill the kmod_thread_locker logic
2014-12-10 17:41:17 -08:00
kprobes.c
kprobes: makes kprobes/enabled works correctly for optimized kprobes.
2015-02-13 21:21:42 -08:00
ksysfs.c
…
kthread.c
…
latencytop.c
…
Makefile
make certificate list change message more useful
2015-07-02 16:42:13 -07:00
module_signing.c
…
module-internal.h
…
module.c
module: Fix load_module() error path
2015-07-09 06:57:12 +09:30
notifier.c
notifiers, RCU: Assert that RCU is watching in notify_die()
2015-07-07 10:59:04 +02:00
nsproxy.c
bury struct proc_ns in fs/proc
2014-12-04 14:34:54 -05:00
padata.c
padata: use %*pb[l] to print bitmaps including cpumasks and nodemasks
2015-02-13 21:21:38 -08:00
panic.c
kernel/panic/kexec: fix "crash_kexec_post_notifiers" option issue in oops path
2015-06-30 19:44:57 -07:00
params.c
Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
2015-07-01 10:49:25 -07:00
pid_namespace.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2014-12-16 15:53:03 -08:00
pid.c
fork: report pid reservation failure properly
2015-04-17 09:04:06 -04:00
profile.c
profile: use %*pb[l] to print bitmaps including cpumasks and nodemasks
2015-02-13 21:21:38 -08:00
ptrace.c
ptrace: ptrace_detach() can no longer race with SIGKILL
2015-04-17 09:04:06 -04:00
range.c
kernel: avoid overflow in cmp_range
2015-01-17 10:02:23 +13:00
reboot.c
kernel/reboot.c: add orderly_reboot for graceful reboot
2015-04-15 16:35:23 -07:00
relay.c
kernel/relay.c: use kvfree() in relay_free_page_array()
2015-06-30 19:44:59 -07:00
resource.c
mm: Fix bugs in region_is_ram()
2015-07-22 17:20:34 +02:00
seccomp.c
seccomp, filter: add and use bpf_prog_create_from_user from seccomp
2015-05-09 17:35:05 -04:00
signal.c
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2015-06-27 13:26:03 -07:00
smp.c
smp: Fix error case handling in smp_call_function_*()
2015-04-19 13:19:23 -07:00
smpboot.c
watchdog: add watchdog_cpumask sysctl to assist nohz
2015-06-24 17:49:40 -07:00
smpboot.h
…
softirq.c
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2015-02-09 15:24:03 -08:00
stacktrace.c
stacktrace: introduce snprint_stack_trace for buffer output
2014-12-13 12:42:48 -08:00
stop_machine.c
sched/stop_machine: Fix deadlock between multiple stop_two_cpus()
2015-06-19 10:03:12 +02:00
sys_ni.c
x86/ldt: Make modify_ldt() optional
2015-07-31 13:30:45 +02:00
sys.c
prctl: more prctl(PR_SET_MM_*) checks
2015-06-25 17:00:37 -07:00
sysctl_binary.c
kernel: add panic_on_warn
2014-12-10 17:41:10 -08:00
sysctl.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2015-07-03 15:20:57 -07:00
system_certificates.S
…
system_keyring.c
…
task_work.c
…
taskstats.c
netlink: make nlmsg_end() and genlmsg_end() void
2015-01-18 01:03:45 -05:00
test_kprobes.c
…
torture.c
rcu: Convert ACCESS_ONCE() to READ_ONCE() and WRITE_ONCE()
2015-05-27 12:56:15 -07:00
tracepoint.c
…
tsacct.c
…
uid16.c
groups: Consolidate the setgroups permission checks
2014-12-05 17:19:27 -06:00
up.c
…
user_namespace.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2014-12-17 12:31:40 -08:00
user-return-notifier.c
…
user.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
2014-12-17 12:31:40 -08:00
utsname_sysctl.c
…
utsname.c
copy address of proc_ns_ops into ns_common
2014-12-04 14:34:47 -05:00
watchdog.c
watchdog: add watchdog_cpumask sysctl to assist nohz
2015-06-24 17:49:40 -07:00
workqueue_internal.h
…
workqueue.c
Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux
2015-07-01 10:49:25 -07:00