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Linus Torvalds 37407ea7f9 Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations" 
This reverts commit 970e178985cadbca660feb02f4d2ee3a09f7fdda.

Nikolay Ulyanitsky reported thatthe 3.6-rc5 kernel has a 15-20%
performance drop on PostgreSQL 9.2 on his machine (running "pgbench").

Borislav Petkov was able to reproduce this, and bisected it to this
commit 970e178985ca ("sched: Improve scalability via 'CPU buddies' ...")
apparently because the new single-idle-buddy model simply doesn't find
idle CPU's to reschedule on aggressively enough.

Mike Galbraith suspects that it is likely due to the user-mode spinlocks
in PostgreSQL not reacting well to preemption, but we don't really know
the details - I'll just revert the commit for now.

There are hopefully other approaches to improve scheduler scalability
without it causing these kinds of downsides.

Reported-by: Nikolay Ulyanitsky <lystor@gmail.com>
Bisected-by: Borislav Petkov <bp@alien8.de>
Acked-by: Mike Galbraith <efault@gmx.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-09-16 12:29:43 -07:00
..
debug
kernel/debug: Make use of KGDB_REASON_NMI
2012-07-31 08:16:43 -05:00
events
perf/hwpb: Invoke __perf_event_disable() if interrupts are already disabled
2012-09-04 17:29:53 +02:00
gcov
gcov: disable CONSTRUCTORS for UML
2011-07-26 16:49:45 -07:00
irq
Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2012-08-03 10:56:44 -07:00
power
Revert "NMI watchdog: fix for lockup detector breakage on resume"
2012-08-08 20:49:45 +02:00
sched
Revert "sched: Improve scalability via 'CPU buddies', which withstand random perturbations"
2012-09-16 12:29:43 -07:00
time
sched: Add missing call to calc_load_exit_idle()
2012-09-04 14:30:29 +02:00
trace
tracing/syscalls: Fix perf syscall tracing when syscall_nr == -1
2012-08-17 15:19:46 -04:00
.gitignore
…
acct.c
Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2012-01-08 12:19:57 -08:00
async.c
[SCSI] async: make async_synchronize_full() flush all work regardless of domain
2012-07-20 09:07:37 +01:00
audit_tree.c
audit: clean up refcounting in audit-tree
2012-08-15 12:55:22 +02:00
audit_watch.c
get rid of kern_path_parent()
2012-07-14 16:35:02 +04:00
audit.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2012-08-01 10:26:23 -07:00
audit.h
audit: remove AUDIT_SETUP_CONTEXT as it isn't used
2012-01-17 16:16:57 -05:00
auditfilter.c
audit: allow interfield comparison in audit rules
2012-01-17 16:17:01 -05:00
auditsc.c
seccomp: remove duplicated failure logging
2012-04-14 11:13:20 +10:00
backtracetest.c
…
bounds.c
memcg: remove direct page_cgroup-to-page pointer
2011-03-23 19:46:28 -07:00
capability.c
userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
2012-05-15 14:59:24 -07:00
cgroup_freezer.c
cgroup: convert all non-memcg controllers to the new cftype interface
2012-04-01 12:09:55 -07:00
cgroup.c
Merge branch 'for-3.6' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2012-07-24 17:47:44 -07:00
compat.c
new helper: sigsuspend()
2012-05-21 23:52:30 -04:00
configs.c
kernel/configs.c: include MODULE_*() when CONFIG_IKCONFIG_PROC=n
2011-07-25 20:57:15 -07:00
cpu_pm.c
kernel/cpu_pm.c: fix various typos
2012-05-31 17:49:27 -07:00
cpu.c
mm/hotplug: correctly setup fallback zonelists when creating new pgdat
2012-07-31 18:42:44 -07:00
cpuset.c
cpusets: Remove/update outdated comments
2012-07-24 13:53:28 +02:00
crash_dump.c
Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
2011-11-06 19:44:47 -08:00
cred.c
keys: kill task_struct->replacement_session_keyring
2012-05-23 22:11:41 -04:00
delayacct.c
KVM: Steal time implementation
2011-07-14 12:59:14 +03:00
dma.c
Remove all #inclusions of asm/system.h
2012-03-28 18:30:03 +01:00
elfcore.c
…
exec_domain.c
sys_personality: remove the bogus checks in sys_personality()->__set_personality() path
2010-08-09 20:45:05 -07:00
exit.c
posix_types.h: Cleanup stale __NFDBITS and related definitions
2012-07-26 13:36:43 -07:00
extable.c
extable: Skip sorting if sorted at build time.
2012-04-19 15:06:55 -07:00
fork.c
uprobes: Fix mmap_region()'s mm->mm_rb corruption if uprobe_mmap() fails
2012-08-21 11:48:12 +02:00
freezer.c
PM / Freezer: Remove references to TIF_FREEZE in comments
2012-03-04 23:08:54 +01:00
futex_compat.c
futex: Mark get_robust_list as deprecated
2012-03-29 11:37:17 +02:00
futex.c
futex: Forbid uaddr == uaddr2 in futex_wait_requeue_pi()
2012-07-24 16:02:57 +02:00
groups.c
userns: Convert in_group_p and in_egroup_p to use kgid_t
2012-05-03 03:29:33 -07:00
hrtimer.c
hrtimer: Update hrtimer base offsets each hrtimer_interrupt
2012-07-11 23:34:39 +02:00
hung_task.c
hung task debugging: Inject NMI when hung and going to panic
2012-04-25 12:39:25 +02:00
irq_work.c
irq_work: fix compile failure on tile from missing include
2012-04-13 13:15:16 -04:00
itimer.c
itimer: Use printk_once instead of WARN_ONCE
2012-04-10 11:00:30 +02:00
jump_label.c
static keys: Inline the static_key_enabled() function
2012-02-28 20:01:08 +01:00
kallsyms.c
vsprintf: fix %ps on non symbols when using kallsyms
2012-05-29 16:22:32 -07:00
kcmp.c
syscalls, x86: add __NR_kcmp syscall
2012-05-31 17:49:32 -07:00
Kconfig.freezer
…
Kconfig.hz
…
Kconfig.locks
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
2012-03-23 13:18:57 +01:00
Kconfig.preempt
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
2012-03-23 13:18:57 +01:00
kexec.c
kdump: append newline to the last lien of vmcoreinfo note
2012-07-30 17:25:20 -07:00
kfifo.c
[media] kernel:kfifo: export __kfifo_max_r symbol
2012-04-11 18:24:37 -03:00
kmod.c
kmod: avoid deadlock from recursive kmod call
2012-07-30 17:25:20 -07:00
kprobes.c
kprobes: return proper error code from register_kprobe()
2012-03-05 15:49:42 -08:00
ksysfs.c
kernel: ksysfs.c is implicitly using stat.h
2011-10-31 09:20:13 -04:00
kthread.c
kthread_worker: reimplement flush_kthread_work() to allow freeing the work item being executed
2012-07-22 10:15:28 -07:00
latencytop.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
lglock.c
brlocks/lglocks: turn into functions
2012-05-29 23:28:41 -04:00
lockdep_internals.h
…
lockdep_proc.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
lockdep_states.h
…
lockdep.c
lockdep: Add CPU-idle/offline warning to lockdep-RCU splat
2012-02-21 09:06:06 -08:00
Makefile
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2012-06-01 10:34:35 -07:00
module.c
Guard check in module loader against integer overflow
2012-05-23 22:28:53 +09:30
mutex-debug.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
mutex-debug.h
mutex: Use p->on_cpu for the adaptive spin
2011-04-14 08:52:33 +02:00
mutex.c
sched/rt: Use schedule_preempt_disabled()
2012-03-01 10:28:03 +01:00
mutex.h
mutex: Use p->on_cpu for the adaptive spin
2011-04-14 08:52:33 +02:00
notifier.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
nsproxy.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
padata.c
padata: Fix cpu hotplug
2012-03-29 19:52:46 +08:00
panic.c
panic: fix a possible deadlock in panic()
2012-07-30 17:25:13 -07:00
params.c
params: replace printk(KERN_<LVL>...) with pr_<lvl>(...)
2012-05-04 17:28:18 -07:00
pid_namespace.c
pidns: guarantee that the pidns init will be the last pidns process reaped
2012-06-20 14:39:36 -07:00
pid.c
mm: add a low limit to alloc_large_system_hash
2012-05-24 00:28:21 -04:00
posix-cpu-timers.c
[S390] cputime: add sparse checking and cleanup
2011-12-15 14:56:19 +01:00
posix-timers.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
printk.c
printk: Fix calculation of length used to discard records
2012-08-12 21:25:50 +03:00
profile.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
ptrace.c
userns: Convert ptrace, kill, set_priority permission checks to work with kuids and kgids
2012-05-03 03:28:51 -07:00
range.c
range: fix bogus misuse of module.h to get printk()
2011-10-31 09:20:11 -04:00
rcu.h
rcu: Allow nesting of rcu_idle_enter() and rcu_idle_exit()
2012-02-21 09:06:12 -08:00
rcupdate.c
rcu: Consolidate tree/tiny __rcu_read_{,un}lock() implementations
2012-07-02 12:34:23 -07:00
rcutiny_plugin.h
rcu: Fix code-style issues involving "else"
2012-07-06 06:01:48 -07:00
rcutiny.c
rcu: Fix rcu_is_cpu_idle() #ifdef in TINY_RCU
2012-07-02 12:34:25 -07:00
rcutorture.c
rcu: Fix broken strings in RCU's source code.
2012-07-06 06:01:49 -07:00
rcutree_plugin.h
rcu: Fix code-style issues involving "else"
2012-07-06 06:01:48 -07:00
rcutree_trace.c
rcu: Fix broken strings in RCU's source code.
2012-07-06 06:01:49 -07:00
rcutree.c
rcu: Fix code-style issues involving "else"
2012-07-06 06:01:48 -07:00
rcutree.h
Merge branches 'bigrtm.2012.07.04a', 'doctorture.2012.07.02a', 'fixes.2012.07.06a' and 'fnh.2012.07.02a' into HEAD
2012-07-06 05:59:30 -07:00
relay.c
splice: fix racy pipe->buffers uses
2012-06-13 21:16:42 +02:00
res_counter.c
rescounters: add res_counter_uncharge_until()
2012-05-29 16:22:27 -07:00
resource.c
resource: make sure requested range is included in the root range
2012-07-30 17:25:21 -07:00
rtmutex_common.h
rtmutex: Simplify PI algorithm and make highest prio task get lock
2011-01-27 21:13:51 -05:00
rtmutex-debug.c
lockdep, rtmutex, bug: Show taint flags on error
2011-12-06 08:16:49 +01:00
rtmutex-debug.h
…
rtmutex-tester.c
rtmutex-tester: convert sysdev_class to a regular subsystem
2011-12-14 14:54:22 -08:00
rtmutex.c
Revert "rcu: Permit rt_mutex_unlock() with irqs disabled"
2011-12-11 10:33:18 -08:00
rtmutex.h
…
rwsem.c
Remove all #inclusions of asm/system.h
2012-03-28 18:30:03 +01:00
seccomp.c
seccomp: fix build warnings when there is no CONFIG_SECCOMP_FILTER
2012-04-18 12:24:52 +10:00
semaphore.c
semaphore: fix improper comment reference to mutex
2012-04-05 17:15:55 -07:00
signal.c
signal: make sure we don't get stopped with pending task_work
2012-07-22 23:57:54 +04:00
smp.c
smp: Remove ipi_call_lock[_irq]()/ipi_call_unlock[_irq]()
2012-06-05 17:27:14 +02:00
smpboot.c
smpboot, idle: Fix comment mismatch over idle_threads_init()
2012-05-24 22:58:08 +02:00
smpboot.h
smpboot: Remove leftover declaration
2012-06-11 15:07:52 +02:00
softirq.c
mm: allow PF_MEMALLOC from softirq context
2012-07-31 18:42:45 -07:00
spinlock.c
locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
2012-03-23 13:18:57 +01:00
srcu.c
rcu: Implement per-domain single-threaded call_srcu() state machine
2012-04-30 10:48:25 -07:00
stacktrace.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
stop_machine.c
Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
2011-11-06 19:44:47 -08:00
sys_ni.c
syscalls, x86: add __NR_kcmp syscall
2012-05-31 17:49:32 -07:00
sys.c
kernel/sys.c: avoid argv_free(NULL)
2012-07-30 17:25:13 -07:00
sysctl_binary.c
mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads
2012-07-31 18:42:40 -07:00
sysctl.c
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2012-08-01 10:26:23 -07:00
task_work.c
task_work: add a scheduling point in task_work_run()
2012-08-21 09:11:44 -07:00
taskstats.c
taskstats: check nla_reserve() return
2012-07-30 17:25:21 -07:00
test_kprobes.c
kprobes: Fix selftest to clear flags field for reusing probes
2010-10-14 08:55:27 +02:00
time.c
time: Remove bogus comments
2012-03-15 18:17:55 -07:00
timeconst.pl
…
timer.c
alpha: take a bunch of syscalls into osf_sys.c
2012-08-19 08:41:19 -07:00
tracepoint.c
static keys: Introduce 'struct static_key', static_key_true()/false() and static_key_slow_[inc|dec]()
2012-02-24 10:05:59 +01:00
tsacct.c
[S390] cputime: add sparse checking and cleanup
2011-12-15 14:56:19 +01:00
uid16.c
userns: Convert setting and getting uid and gid system calls to use kuid and kgid
2012-05-03 03:28:41 -07:00
up.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
user_namespace.c
userns: Store uid and gid values in struct cred with kuid_t and kgid_t types
2012-05-03 03:28:38 -07:00
user-return-notifier.c
kernel: Map most files to use export.h instead of module.h
2011-10-31 09:20:12 -04:00
user.c
userns: Silence silly gcc warning.
2012-05-19 15:44:40 -06:00
utsname_sysctl.c
Merge branch 'modsplit-Oct31_2011' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
2011-11-06 19:44:47 -08:00
utsname.c
userns: Use cred->user_ns instead of cred->user->user_ns
2012-04-07 16:55:51 -07:00
wait.c
lockdep/waitqueues: Add better annotation
2011-12-21 10:07:39 +01:00
watchdog.c
Revert "NMI watchdog: fix for lockup detector breakage on resume"
2012-08-08 20:49:45 +02:00
workqueue_sched.h
workqueue: implement concurrency managed dynamic worker pool
2010-06-29 10:07:14 +02:00
workqueue.c
workqueue: fix possible idle worker depletion across CPU hotplug
2012-09-10 10:05:54 -07:00