Gregory Haskins 73fe6aae84 sched: add RT-balance cpu-weight ... Some RT tasks (particularly kthreads) are bound to one specific CPU. It is fairly common for two or more bound tasks to get queued up at the same time. Consider, for instance, softirq_timer and softirq_sched. A timer goes off in an ISR which schedules softirq_thread to run at RT50. Then the timer handler determines that it's time to smp-rebalance the system so it schedules softirq_sched to run. So we are in a situation where we have two RT50 tasks queued, and the system will go into rt-overload condition to request other CPUs for help. This causes two problems in the current code: 1) If a high-priority bound task and a low-priority unbounded task queue up behind the running task, we will fail to ever relocate the unbounded task because we terminate the search on the first unmovable task. 2) We spend precious futile cycles in the fast-path trying to pull overloaded tasks over. It is therefore optimial to strive to avoid the overhead all together if we can cheaply detect the condition before overload even occurs. This patch tries to achieve this optimization by utilizing the hamming weight of the task->cpus_allowed mask. A weight of 1 indicates that the task cannot be migrated. We will then utilize this information to skip non-migratable tasks and to eliminate uncessary rebalance attempts. We introduce a per-rq variable to count the number of migratable tasks that are currently running. We only go into overload if we have more than one rt task, AND at least one of them is migratable. In addition, we introduce a per-task variable to cache the cpus_allowed weight, since the hamming calculation is probably relatively expensive. We only update the cached value when the mask is updated which should be relatively infrequent, especially compared to scheduling frequency in the fast path. Signed-off-by: Gregory Haskins <ghaskins@novell.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2008-01-25 21:08:07 +01:00
..
irq	genirq: revert lazy irq disable for simple irqs	2007-12-18 18:05:58 +01:00
power	driver core: make /sys/power a kobject	2008-01-24 20:40:25 -08:00
time	Driver core: change sysdev classes to use dynamic kobject names	2008-01-24 20:40:40 -08:00
.gitignore
acct.c	acct: real_parent ppid	2008-01-07 14:55:37 -08:00
audit_tree.c	[PATCH] audit: watching subtrees	2007-10-21 02:37:45 -04:00
audit.c	[PATCH] audit: watching subtrees	2007-10-21 02:37:45 -04:00
audit.h	[PATCH] audit: watching subtrees	2007-10-21 02:37:45 -04:00
auditfilter.c	[PATCH] audit: watching subtrees	2007-10-21 02:37:45 -04:00
auditsc.c	auditsc: fix kernel-doc param warnings	2007-10-22 19:40:02 -07:00
capability.c	Uninline find_pid etc set of functions	2007-10-19 11:53:41 -07:00
cgroup_debug.c	Task Control Groups: simple task cgroup debug info subsystem	2007-10-19 11:53:36 -07:00
cgroup.c	Improve cgroup printks	2007-11-14 18:45:37 -08:00
compat.c	Merge ssh://master.kernel.org/pub/scm/linux/kernel/git/tglx/linux-2.6-hrt	2007-10-18 15:12:41 -07:00
configs.c	use simple_read_from_buffer in kernel/	2007-05-09 12:30:49 -07:00
cpu.c	cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()	2008-01-25 21:08:02 +01:00
cpuset.c	cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()	2008-01-25 21:08:02 +01:00
delayacct.c	Add scaled time to taskstats based process accounting	2007-10-18 14:37:28 -07:00
dma.c	whitespace fixes: DMA channel allocator	2007-10-18 14:37:24 -07:00
exec_domain.c	whitespace fixes: execution domains	2007-10-18 14:37:26 -07:00
exit.c	wait_task_stopped(): pass correct exit_code to wait_noreap_copyout()	2007-11-29 09:24:55 -08:00
extable.c
fork.c	sched: add RT-balance cpu-weight	2008-01-25 21:08:07 +01:00
futex_compat.c	[FUTEX] Fix address computation in compat code.	2007-11-09 16:13:08 -08:00
futex.c	futex: Prevent stale futex owner when interrupted/timeout	2008-01-08 16:21:39 -08:00
hrtimer.c	hrtimer: fix section mismatch	2008-01-21 19:39:41 -08:00
itimer.c	whitespace fixes: interval timers	2007-10-18 14:37:26 -07:00
kallsyms.c	FRV: fix the extern declaration of kallsyms_num_syms	2007-11-29 09:24:54 -08:00
Kconfig.hz	[PATCH] HZ: 300Hz support	2006-12-07 08:39:36 -08:00
Kconfig.instrumentation	Tiny clean-up of OPROFILE/KPROBES configuration	2007-12-06 09:41:12 -08:00
Kconfig.preempt	Move PREEMPT_NOTIFIERS into an always-included Kconfig	2007-10-17 08:42:55 -07:00
kexec.c	vmcoreinfo: add the array length of "free_list" for filtering free pages	2008-01-08 16:10:36 -08:00
kfifo.c	is_power_of_2: kernel/kfifo.c	2007-07-16 09:05:50 -07:00
kmod.c	Fix unbalanced helper_lock in kernel/kmod.c	2008-01-17 15:38:59 -08:00
kprobes.c	kprobes: support kretprobe blacklist	2007-10-16 09:43:10 -07:00
ksysfs.c	Kobject: convert remaining kobject_unregister() to kobject_put()	2008-01-24 20:40:40 -08:00
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	lockdep: Avoid /proc/lockdep & lock_stat infinite output	2007-10-11 22:11:11 +02:00
lockdep.c	softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks	2008-01-25 21:08:02 +01:00
Makefile	revert "Task Control Groups: example CPU accounting subsystem"	2007-11-14 18:45:40 -08:00
marker.c	Linux Kernel Markers: fix marker mutex not taken upon module load	2007-11-14 18:45:40 -08:00
module.c	Kobject: convert remaining kobject_unregister() to kobject_put()	2008-01-24 20:40:40 -08:00
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	lockdep: fixup mutex annotations	2007-10-11 22:11:12 +02:00
mutex.h	[PATCH] lockdep: prove mutex locking correctness	2006-07-03 15:27:04 -07:00
notifier.c	Add kernel/notifier.c	2007-10-19 11:53:34 -07:00
ns_cgroup.c	cgroups: implement namespace tracking subsystem	2007-10-19 11:53:37 -07:00
nsproxy.c	pid namespaces: allow cloning of new namespace	2007-10-19 11:53:39 -07:00
panic.c	debug: add end-of-oops marker	2007-12-20 15:01:17 +01:00
params.c	Modules: remove unneeded release function	2008-01-24 20:40:39 -08:00
pid.c	pidns: Place under CONFIG_EXPERIMENTAL	2007-11-14 18:45:43 -08:00
posix-cpu-timers.c	Isolate some explicit usage of task->tgid	2007-10-19 11:53:40 -07:00
posix-timers.c	Isolate some explicit usage of task->tgid	2007-10-19 11:53:40 -07:00
printk.c	sched: remove printk_clock()	2008-01-25 21:07:59 +01:00
profile.c	sched: document profile=sleep requiring CONFIG_SCHEDSTATS	2007-10-24 18:23:50 +02:00
ptrace.c	ptrace: Call arch_ptrace_attach() when request=PTRACE_TRACEME	2008-01-25 08:31:39 +01:00
rcupdate.c	rcu: fix section mismatch	2008-01-22 09:17:48 -08:00
rcutorture.c	cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()	2008-01-25 21:08:02 +01:00
relay.c	whitespace fixes: relayfs	2007-10-18 14:37:24 -07:00
resource.c	Add IORESOUCE_BUSY flag for System RAM	2007-11-14 18:45:39 -08:00
rtmutex_common.h	FUTEX: Tidy up the code	2007-07-16 09:05:49 -07:00
rtmutex-debug.c	Use helpers to obtain task pid in printks	2007-10-19 11:53:43 -07:00
rtmutex-debug.h	[PATCH] lockdep: better lock debugging	2006-07-03 15:27:01 -07:00
rtmutex-tester.c	Driver core: change sysdev classes to use dynamic kobject names	2008-01-24 20:40:40 -08:00
rtmutex.c	Use helpers to obtain task pid in printks	2007-10-19 11:53:43 -07:00
rtmutex.h	[PATCH] lockdep: better lock debugging	2006-07-03 15:27:01 -07:00
rwsem.c	sched: mark rwsem functions as __sched for wchan/profiling	2007-12-18 15:21:13 +01:00
sched_debug.c	sched: fix gcc warnings	2007-12-30 17:24:35 +01:00
sched_fair.c	sched: group scheduler, fix fairness of cpu bandwidth allocation for task groups	2008-01-25 21:08:00 +01:00
sched_idletask.c	sched: isolate SMP balancing code a bit more	2007-10-24 18:23:51 +02:00
sched_rt.c	sched: add RT-balance cpu-weight	2008-01-25 21:08:07 +01:00
sched_stats.h	sched: clean up kernel/sched_stat.h	2007-11-28 15:52:56 +01:00
sched.c	sched: add RT-balance cpu-weight	2008-01-25 21:08:07 +01:00
seccomp.c	make seccomp zerocost in schedule	2007-07-16 09:05:50 -07:00
signal.c	sigwait eats blocked default-ignore signals	2007-11-12 16:05:23 -08:00
softirq.c	[KERNEL]: Unexport raise_softirq_irqoff	2007-10-10 16:49:18 -07:00
softlockup.c	softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks	2008-01-25 21:08:02 +01:00
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	cpu-hotplug: replace lock_cpu_hotplug() with get_online_cpus()	2008-01-25 21:08:02 +01:00
sys_ni.c	[COMPAT]: Fix build on COMPAT platforms when CONFIG_NET is disabled.	2007-10-30 21:29:56 -07:00
sys.c	x86: ignore the sys_getcpu() tcache parameter	2007-11-17 16:27:00 +01:00
sysctl_check.c	sysctl: fix ax25 checks	2007-12-17 19:28:17 -08:00
sysctl.c	softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks	2008-01-25 21:08:02 +01:00
taskstats.c	kernel/taskstats.c: fix bogus nlmsg_free()	2007-11-14 18:45:44 -08:00
time.c	whitespace fixes: time syscalls	2007-10-18 14:37:24 -07:00
timer.c	timer: fix section mismatch	2008-01-21 19:39:41 -08:00
tsacct.c	Add scaled time to taskstats based process accounting	2007-10-18 14:37:28 -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 user namespace exiting OOPs	2007-09-19 11:24:18 -07:00
user.c	Kobject: convert kernel/user.c to use kobject_init/add_ng()	2008-01-24 20:40:31 -08:00
utsname_sysctl.c	Isolate the UTS namespace's domainname and hostname back	2007-11-29 09:24:53 -08:00
utsname.c	Fix UTS corruption during clone(CLONE_NEWUTS)	2007-09-19 11:24:17 -07:00
wait.c	Fix occurrences of "the the "	2007-05-09 08:57:56 +02:00
workqueue.c	cpu-hotplug: replace per-subsystem mutexes with get_online_cpus()	2008-01-25 21:08:02 +01:00