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Peter Williams a4ac01c36e sched: fix bug in balance_tasks() 
There are two problems with balance_tasks() and how it used:

1. The variables best_prio and best_prio_seen (inherited from the old
move_tasks()) were only required to handle problems caused by the
active/expired arrays, the order in which they were processed and the
possibility that the task with the highest priority could be on either.
  These issues are no longer present and the extra overhead associated
with their use is unnecessary (and possibly wrong).

2. In the absence of CONFIG_FAIR_GROUP_SCHED being set, the same
this_best_prio variable needs to be used by all scheduling classes or
there is a risk of moving too much load.  E.g. if the highest priority
task on this at the beginning is a fairly low priority task and the rt
class migrates a task (during its turn) then that moved task becomes the
new highest priority task on this_rq but when the sched_fair class
initializes its copy of this_best_prio it will get the priority of the
original highest priority task as, due to the run queue locks being
held, the reschedule triggered by pull_task() will not have taken place.
  This could result in inappropriate overriding of skip_for_load and
excessive load being moved.

The attached patch addresses these problems by deleting all reference to
best_prio and best_prio_seen and making this_best_prio a reference
parameter to the various functions involved.

load_balance_fair() has also been modified so that this_best_prio is
only reset (in the loop) if CONFIG_FAIR_GROUP_SCHED is set.  This should
preserve the effect of helping spread groups' higher priority tasks
around the available CPUs while improving system performance when
CONFIG_FAIR_GROUP_SCHED isn't set.

Signed-off-by: Peter Williams <pwil3058@bigpond.net.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-08-09 11:16:46 +02:00
..
irq genirq: temporary fix for level-triggered IRQ resend 2007-08-01 20:46:22 -07:00
power Introduce CONFIG_SUSPEND for suspend-to-Ram and standby 2007-07-29 16:45:38 -07:00
time Fix leaks on /proc/{*/sched,sched_debug,timer_list,timer_stats} 2007-07-31 15:39:40 -07:00
.gitignore
acct.c Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time(). 2007-07-25 10:09:20 -07:00
audit.c Freezer: make kernel threads nonfreezable by default 2007-07-17 10:23:02 -07:00
audit.h Audit: add TTY input auditing 2007-07-16 09:05:47 -07:00
auditfilter.c [PATCH] allow audit filtering on bit & operations 2007-07-22 09:57:02 -04:00
auditsc.c audit: fix two bugs in the new execve audit code 2007-07-28 19:42:22 -07:00
capability.c [PATCH] pid: replace do/while_each_task_pid with do/while_each_pid_task 2007-02-12 09:48:32 -08:00
compat.c signal/timer/event: timerfd compat code 2007-05-11 08:29:36 -07:00
configs.c use simple_read_from_buffer in kernel/ 2007-05-09 12:30:49 -07:00
cpu.c HOTPLUG: Add CPU_DYING notifier 2007-07-16 12:05:49 +03:00
cpuset.c usermodehelper: Tidy up waiting 2007-07-18 08:47:40 -07:00
delayacct.c sched: update delay-accounting to use CFS's precise stats 2007-07-09 18:52:00 +02:00
die_notifier.c move die notifier handling to common code 2007-05-08 11:15:04 -07:00
dma.c [PATCH] struct seq_operations and struct file_operations constification 2006-12-07 08:39:46 -08:00
exec_domain.c Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
exit.c Kill some obsolete sub-thread-ptrace stuff 2007-08-03 15:06:33 -07:00
extable.c [PATCH] symbol_put_addr() locks kernel 2006-05-15 11:20:55 -07:00
fork.c mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
futex_compat.c Revert "futex_requeue_pi optimization" 2007-06-18 09:48:41 -07:00
futex.c futex: pass nr_wake2 to futex_wake_op 2007-07-31 15:39:40 -07:00
hrtimer.c Cache xtime every call to update_wall_time 2007-07-25 10:17:44 -07:00
itimer.c The scheduled -EINVAL for invalid timevals in setitimer 2007-05-08 11:15:13 -07:00
kallsyms.c kallsyms: make KSYM_NAME_LEN include space for trailing '\0' 2007-07-17 10:23:03 -07:00
Kconfig.hz [PATCH] HZ: 300Hz support 2006-12-07 08:39:36 -08:00
Kconfig.preempt [PATCH] sched: arch preempt notifier mechanism 2007-07-26 13:40:43 +02:00
kexec.c kdump/kexec: calculate note size at compile time 2007-05-08 11:15:07 -07:00
kfifo.c is_power_of_2: kernel/kfifo.c 2007-07-16 09:05:50 -07:00
kmod.c kernel-doc fix for kmod.c 2007-07-26 11:33:06 -07:00
kprobes.c jprobes: make jprobes a little safer for users 2007-07-19 10:04:44 -07:00
ksysfs.c FRV: Fix linkage problems 2007-07-20 12:01:34 -07:00
kthread.c kthread: silence bogus section mismatch warning 2007-07-31 15:39:42 -07:00
latency.c [PATCH] severing module.h->sched.h 2006-12-04 02:00:22 -05:00
lockdep_internals.h [PATCH] lockdep: more chains 2006-12-07 08:39:43 -08:00
lockdep_proc.c Fix leak on /proc/lockdep_stats 2007-07-31 15:39:40 -07:00
lockdep.c lockdep debugging: give stacktrace for init_error 2007-07-19 10:04:49 -07:00
Makefile user namespace: add the framework 2007-07-16 09:05:47 -07:00
module.c kallsyms: make KSYM_NAME_LEN include space for trailing '\0' 2007-07-17 10:23:03 -07:00
mutex-debug.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00
mutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
mutex.c lockstat: measure lock bouncing 2007-07-19 10:04:49 -07:00
mutex.h [PATCH] lockdep: prove mutex locking correctness 2006-07-03 15:27:04 -07:00
nsproxy.c mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
panic.c Report that kernel is tainted if there was an OOPS 2007-07-17 10:23:02 -07:00
params.c modules: better error messages when modules fail to load due to a sysfs problem. 2007-07-30 14:25:23 -07:00
pid.c namespace: ensure clone_flags are always stored in an unsigned long 2007-07-16 09:05:48 -07:00
posix-cpu-timers.c sched: make posix-cpu-timers use CFS's accounting information 2007-07-09 18:51:58 +02:00
posix-timers.c mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
printk.c serial: fix 8250 early console setup 2007-08-03 15:02:56 -07:00
profile.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
ptrace.c coredump masking: reimplementation of dumpable using two flags 2007-07-19 10:04:46 -07:00
rcupdate.c Add suspend-related notifications for CPU hotplug 2007-05-09 12:30:56 -07:00
rcutorture.c Freezer: make kernel threads nonfreezable by default 2007-07-17 10:23:02 -07:00
relay.c Fix a use after free bug in kernel->userspace relay file support 2007-07-31 15:39:42 -07:00
resource.c libata/IDE: remove combined mode quirk 2007-04-28 14:15:59 -04:00
rtmutex_common.h FUTEX: Tidy up the code 2007-07-16 09:05:49 -07:00
rtmutex-debug.c FUTEX: Tidy up the code 2007-07-16 09:05:49 -07:00
rtmutex-debug.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rtmutex-tester.c Freezer: make kernel threads nonfreezable by default 2007-07-17 10:23:02 -07:00
rtmutex.c FUTEX: Tidy up the code 2007-07-16 09:05:49 -07:00
rtmutex.h [PATCH] lockdep: better lock debugging 2006-07-03 15:27:01 -07:00
rwsem.c lockstat: hook into spinlock_t, rwlock_t, rwsem and mutex 2007-07-19 10:04:49 -07:00
sched_debug.c take sched_debug.c out of nasal demon territory 2007-08-06 18:22:27 -07:00
sched_fair.c sched: fix bug in balance_tasks() 2007-08-09 11:16:46 +02:00
sched_idletask.c sched: fix bug in balance_tasks() 2007-08-09 11:16:46 +02:00
sched_rt.c sched: fix bug in balance_tasks() 2007-08-09 11:16:46 +02:00
sched_stats.h [PATCH] sched: add schedstat_set() API 2007-08-02 17:41:40 +02:00
sched.c sched: fix bug in balance_tasks() 2007-08-09 11:16:46 +02:00
seccomp.c make seccomp zerocost in schedule 2007-07-16 09:05:50 -07:00
signal.c Kill some obsolete sub-thread-ptrace stuff 2007-08-03 15:06:33 -07:00
softirq.c Freezer: make kernel threads nonfreezable by default 2007-07-17 10:23:02 -07:00
softlockup.c Freezer: make kernel threads nonfreezable by default 2007-07-17 10:23:02 -07:00
spinlock.c lockstat: hook into spinlock_t, rwlock_t, rwsem and mutex 2007-07-19 10:04:49 -07:00
srcu.c [PATCH] SRCU: report out-of-memory errors 2006-10-04 07:55:30 -07:00
stacktrace.c [PATCH] lockdep: stacktrace subsystem, core 2006-07-03 15:27:02 -07:00
stop_machine.c Fix stop_machine_run problem with naughty real time process 2007-07-16 09:05:41 -07:00
sys_ni.c diskquota: 32bit quota tools on 64bit architectures 2007-07-16 09:05:48 -07:00
sys.c Replace CONFIG_SOFTWARE_SUSPEND with CONFIG_HIBERNATION 2007-07-29 16:45:38 -07:00
sysctl.c ACPI: restore CONFIG_ACPI_SLEEP 2007-07-29 16:53:59 -07:00
taskstats.c taskstats: add context-switch counters 2007-07-16 09:05:46 -07:00
time.c Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time(). 2007-07-25 10:09:20 -07:00
timer.c Pull ia64-clocksource into release branch 2007-07-20 11:26:47 -07:00
tsacct.c Cleanup non-arch xtime uses, use get_seconds() or current_kernel_time(). 2007-07-25 10:09:20 -07:00
uid16.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
user_namespace.c fix create_new_namespaces() return value 2007-07-16 09:05:47 -07:00
user.c mm: Remove slab destructors from kmem_cache_create(). 2007-07-20 10:11:58 +09:00
utsname_sysctl.c remove CONFIG_UTS_NS and CONFIG_IPC_NS 2007-07-16 09:05:47 -07:00
utsname.c namespace: ensure clone_flags are always stored in an unsigned long 2007-07-16 09:05:48 -07:00
wait.c Fix occurrences of "the the " 2007-05-09 08:57:56 +02:00
workqueue.c destroy_workqueue() can livelock 2007-07-17 10:23:03 -07:00