[git pull] scheduler fixes
From: Ingo Molnar
Date: Mon May 05 2008 - 18:59:13 EST
Linus, please pull the latest scheduler fixes git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/mingo/linux-2.6-sched-fixes.git for-linus
this tree got booted up ~10 times on x86. Thanks,
Ingo
------------------>
Andrew Morton (1):
sched: add debug checks to idle functions
David Simner (1):
sched: fix sched_info_switch not being called according to documentation
Gregory Haskins (2):
sched: fix RT task-wakeup logic
sched: fix SCHED_FAIR wake-idle logic error
Harvey Harrison (2):
sched: make rt_sched_class, idle_sched_class static
sched: add statics, don't return void expressions
Heiko Carstens (1):
sched: fix missing locking in sched_domains code
Ingo Molnar (4):
sched: remove old sched doc
sched: make clock sync tunable by architecture code
sched: fix cpu clock
sched, x86: add HAVE_UNSTABLE_SCHED_CLOCK
Miao Xie (1):
sched: fair-group: fix a Div0 error of the fair group scheduler
Mike Galbraith (1):
sched: fix debugging
Parag Warudkar (1):
sched: default to n for GROUP_SCHED and FAIR_GROUP_SCHED
Peter Zijlstra (4):
sched: fix normalized sleeper
sched: optimize calc_delta_mine()
sched: fix hrtick_start_fair and CPU-Hotplug
sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
Documentation/scheduler/sched-design.txt | 165 ---------------
arch/x86/Kconfig | 1 +
include/linux/sched.h | 38 ++++-
init/Kconfig | 11 +-
init/main.c | 1 +
kernel/Makefile | 2 +-
kernel/sched.c | 323 ++++++++++++------------------
kernel/sched_clock.c | 236 ++++++++++++++++++++++
kernel/sched_debug.c | 7 -
kernel/sched_fair.c | 39 +---
kernel/sched_idletask.c | 2 +-
kernel/sched_rt.c | 9 +-
12 files changed, 428 insertions(+), 406 deletions(-)
delete mode 100644 Documentation/scheduler/sched-design.txt
create mode 100644 kernel/sched_clock.c
diff --git a/Documentation/scheduler/sched-design.txt b/Documentation/scheduler/sched-design.txt
deleted file mode 100644
index 1605bf0..0000000
--- a/Documentation/scheduler/sched-design.txt
+++ /dev/null
@@ -1,165 +0,0 @@
- Goals, Design and Implementation of the
- new ultra-scalable O(1) scheduler
-
-
- This is an edited version of an email Ingo Molnar sent to
- lkml on 4 Jan 2002. It describes the goals, design, and
- implementation of Ingo's new ultra-scalable O(1) scheduler.
- Last Updated: 18 April 2002.
-
-
-Goal
-====
-
-The main goal of the new scheduler is to keep all the good things we know
-and love about the current Linux scheduler:
-
- - good interactive performance even during high load: if the user
- types or clicks then the system must react instantly and must execute
- the user tasks smoothly, even during considerable background load.
-
- - good scheduling/wakeup performance with 1-2 runnable processes.
-
- - fairness: no process should stay without any timeslice for any
- unreasonable amount of time. No process should get an unjustly high
- amount of CPU time.
-
- - priorities: less important tasks can be started with lower priority,
- more important tasks with higher priority.
-
- - SMP efficiency: no CPU should stay idle if there is work to do.
-
- - SMP affinity: processes which run on one CPU should stay affine to
- that CPU. Processes should not bounce between CPUs too frequently.
-
- - plus additional scheduler features: RT scheduling, CPU binding.
-
-and the goal is also to add a few new things:
-
- - fully O(1) scheduling. Are you tired of the recalculation loop
- blowing the L1 cache away every now and then? Do you think the goodness
- loop is taking a bit too long to finish if there are lots of runnable
- processes? This new scheduler takes no prisoners: wakeup(), schedule(),
- the timer interrupt are all O(1) algorithms. There is no recalculation
- loop. There is no goodness loop either.
-
- - 'perfect' SMP scalability. With the new scheduler there is no 'big'
- runqueue_lock anymore - it's all per-CPU runqueues and locks - two
- tasks on two separate CPUs can wake up, schedule and context-switch
- completely in parallel, without any interlocking. All
- scheduling-relevant data is structured for maximum scalability.
-
- - better SMP affinity. The old scheduler has a particular weakness that
- causes the random bouncing of tasks between CPUs if/when higher
- priority/interactive tasks, this was observed and reported by many
- people. The reason is that the timeslice recalculation loop first needs
- every currently running task to consume its timeslice. But when this
- happens on eg. an 8-way system, then this property starves an
- increasing number of CPUs from executing any process. Once the last
- task that has a timeslice left has finished using up that timeslice,
- the recalculation loop is triggered and other CPUs can start executing
- tasks again - after having idled around for a number of timer ticks.
- The more CPUs, the worse this effect.
-
- Furthermore, this same effect causes the bouncing effect as well:
- whenever there is such a 'timeslice squeeze' of the global runqueue,
- idle processors start executing tasks which are not affine to that CPU.
- (because the affine tasks have finished off their timeslices already.)
-
- The new scheduler solves this problem by distributing timeslices on a
- per-CPU basis, without having any global synchronization or
- recalculation.
-
- - batch scheduling. A significant proportion of computing-intensive tasks
- benefit from batch-scheduling, where timeslices are long and processes
- are roundrobin scheduled. The new scheduler does such batch-scheduling
- of the lowest priority tasks - so nice +19 jobs will get
- 'batch-scheduled' automatically. With this scheduler, nice +19 jobs are
- in essence SCHED_IDLE, from an interactiveness point of view.
-
- - handle extreme loads more smoothly, without breakdown and scheduling
- storms.
-
- - O(1) RT scheduling. For those RT folks who are paranoid about the
- O(nr_running) property of the goodness loop and the recalculation loop.
-
- - run fork()ed children before the parent. Andrea has pointed out the
- advantages of this a few months ago, but patches for this feature
- do not work with the old scheduler as well as they should,
- because idle processes often steal the new child before the fork()ing
- CPU gets to execute it.
-
-
-Design
-======
-
-The core of the new scheduler contains the following mechanisms:
-
- - *two* priority-ordered 'priority arrays' per CPU. There is an 'active'
- array and an 'expired' array. The active array contains all tasks that
- are affine to this CPU and have timeslices left. The expired array
- contains all tasks which have used up their timeslices - but this array
- is kept sorted as well. The active and expired array is not accessed
- directly, it's accessed through two pointers in the per-CPU runqueue
- structure. If all active tasks are used up then we 'switch' the two
- pointers and from now on the ready-to-go (former-) expired array is the
- active array - and the empty active array serves as the new collector
- for expired tasks.
-
- - there is a 64-bit bitmap cache for array indices. Finding the highest
- priority task is thus a matter of two x86 BSFL bit-search instructions.
-
-the split-array solution enables us to have an arbitrary number of active
-and expired tasks, and the recalculation of timeslices can be done
-immediately when the timeslice expires. Because the arrays are always
-access through the pointers in the runqueue, switching the two arrays can
-be done very quickly.
-
-this is a hybride priority-list approach coupled with roundrobin
-scheduling and the array-switch method of distributing timeslices.
-
- - there is a per-task 'load estimator'.
-
-one of the toughest things to get right is good interactive feel during
-heavy system load. While playing with various scheduler variants i found
-that the best interactive feel is achieved not by 'boosting' interactive
-tasks, but by 'punishing' tasks that want to use more CPU time than there
-is available. This method is also much easier to do in an O(1) fashion.
-
-to establish the actual 'load' the task contributes to the system, a
-complex-looking but pretty accurate method is used: there is a 4-entry
-'history' ringbuffer of the task's activities during the last 4 seconds.
-This ringbuffer is operated without much overhead. The entries tell the
-scheduler a pretty accurate load-history of the task: has it used up more
-CPU time or less during the past N seconds. [the size '4' and the interval
-of 4x 1 seconds was found by lots of experimentation - this part is
-flexible and can be changed in both directions.]
-
-the penalty a task gets for generating more load than the CPU can handle
-is a priority decrease - there is a maximum amount to this penalty
-relative to their static priority, so even fully CPU-bound tasks will
-observe each other's priorities, and will share the CPU accordingly.
-
-the SMP load-balancer can be extended/switched with additional parallel
-computing and cache hierarchy concepts: NUMA scheduling, multi-core CPUs
-can be supported easily by changing the load-balancer. Right now it's
-tuned for my SMP systems.
-
-i skipped the prev->mm == next->mm advantage - no workload i know of shows
-any sensitivity to this. It can be added back by sacrificing O(1)
-schedule() [the current and one-lower priority list can be searched for a
-that->mm == current->mm condition], but costs a fair number of cycles
-during a number of important workloads, so i wanted to avoid this as much
-as possible.
-
-- the SMP idle-task startup code was still racy and the new scheduler
-triggered this. So i streamlined the idle-setup code a bit. We do not call
-into schedule() before all processors have started up fully and all idle
-threads are in place.
-
-- the patch also cleans up a number of aspects of sched.c - moves code
-into other areas of the kernel where it's appropriate, and simplifies
-certain code paths and data constructs. As a result, the new scheduler's
-code is smaller than the old one.
-
- Ingo
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 845ea2b..bbcafaa 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -18,6 +18,7 @@ config X86_64
### Arch settings
config X86
def_bool y
+ select HAVE_UNSTABLE_SCHED_CLOCK
select HAVE_IDE
select HAVE_OPROFILE
select HAVE_KPROBES
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 03c2380..0c35b03 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -158,6 +158,8 @@ print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
}
#endif
+extern unsigned long long time_sync_thresh;
+
/*
* Task state bitmask. NOTE! These bits are also
* encoded in fs/proc/array.c: get_task_state().
@@ -1551,6 +1553,35 @@ static inline int set_cpus_allowed(struct task_struct *p, cpumask_t new_mask)
extern unsigned long long sched_clock(void);
+#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+static inline void sched_clock_init(void)
+{
+}
+
+static inline u64 sched_clock_cpu(int cpu)
+{
+ return sched_clock();
+}
+
+static inline void sched_clock_tick(void)
+{
+}
+
+static inline void sched_clock_idle_sleep_event(void)
+{
+}
+
+static inline void sched_clock_idle_wakeup_event(u64 delta_ns)
+{
+}
+#else
+extern void sched_clock_init(void);
+extern u64 sched_clock_cpu(int cpu);
+extern void sched_clock_tick(void);
+extern void sched_clock_idle_sleep_event(void);
+extern void sched_clock_idle_wakeup_event(u64 delta_ns);
+#endif
+
/*
* For kernel-internal use: high-speed (but slightly incorrect) per-cpu
* clock constructed from sched_clock():
@@ -1977,6 +2008,11 @@ static inline void clear_tsk_need_resched(struct task_struct *tsk)
clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
}
+static inline int test_tsk_need_resched(struct task_struct *tsk)
+{
+ return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
+}
+
static inline int signal_pending(struct task_struct *p)
{
return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
@@ -1991,7 +2027,7 @@ static inline int fatal_signal_pending(struct task_struct *p)
static inline int need_resched(void)
{
- return unlikely(test_thread_flag(TIF_NEED_RESCHED));
+ return unlikely(test_tsk_need_resched(current));
}
/*
diff --git a/init/Kconfig b/init/Kconfig
index f0e62e5..4c33316 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -316,9 +316,16 @@ config CPUSETS
Say N if unsure.
+#
+# Architectures with an unreliable sched_clock() should select this:
+#
+config HAVE_UNSTABLE_SCHED_CLOCK
+ bool
+
config GROUP_SCHED
bool "Group CPU scheduler"
- default y
+ depends on EXPERIMENTAL
+ default n
help
This feature lets CPU scheduler recognize task groups and control CPU
bandwidth allocation to such task groups.
@@ -326,7 +333,7 @@ config GROUP_SCHED
config FAIR_GROUP_SCHED
bool "Group scheduling for SCHED_OTHER"
depends on GROUP_SCHED
- default y
+ default GROUP_SCHED
config RT_GROUP_SCHED
bool "Group scheduling for SCHED_RR/FIFO"
diff --git a/init/main.c b/init/main.c
index a87d4ca..ddada7a 100644
--- a/init/main.c
+++ b/init/main.c
@@ -602,6 +602,7 @@ asmlinkage void __init start_kernel(void)
softirq_init();
timekeeping_init();
time_init();
+ sched_clock_init();
profile_init();
if (!irqs_disabled())
printk("start_kernel(): bug: interrupts were enabled early\n");
diff --git a/kernel/Makefile b/kernel/Makefile
index 188c432..1c9938a 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -9,7 +9,7 @@ obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
rcupdate.o extable.o params.o posix-timers.o \
kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
hrtimer.o rwsem.o nsproxy.o srcu.o semaphore.o \
- notifier.o ksysfs.o pm_qos_params.o
+ notifier.o ksysfs.o pm_qos_params.o sched_clock.o
obj-$(CONFIG_SYSCTL_SYSCALL_CHECK) += sysctl_check.o
obj-$(CONFIG_STACKTRACE) += stacktrace.o
diff --git a/kernel/sched.c b/kernel/sched.c
index 34bcc5b..58fb8af 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -75,16 +75,6 @@
#include <asm/irq_regs.h>
/*
- * Scheduler clock - returns current time in nanosec units.
- * This is default implementation.
- * Architectures and sub-architectures can override this.
- */
-unsigned long long __attribute__((weak)) sched_clock(void)
-{
- return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
-}
-
-/*
* Convert user-nice values [ -20 ... 0 ... 19 ]
* to static priority [ MAX_RT_PRIO..MAX_PRIO-1 ],
* and back.
@@ -242,6 +232,12 @@ static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
}
#endif
+/*
+ * sched_domains_mutex serializes calls to arch_init_sched_domains,
+ * detach_destroy_domains and partition_sched_domains.
+ */
+static DEFINE_MUTEX(sched_domains_mutex);
+
#ifdef CONFIG_GROUP_SCHED
#include <linux/cgroup.h>
@@ -308,9 +304,6 @@ static DEFINE_PER_CPU(struct rt_rq, init_rt_rq) ____cacheline_aligned_in_smp;
*/
static DEFINE_SPINLOCK(task_group_lock);
-/* doms_cur_mutex serializes access to doms_cur[] array */
-static DEFINE_MUTEX(doms_cur_mutex);
-
#ifdef CONFIG_FAIR_GROUP_SCHED
#ifdef CONFIG_USER_SCHED
# define INIT_TASK_GROUP_LOAD (2*NICE_0_LOAD)
@@ -318,7 +311,13 @@ static DEFINE_MUTEX(doms_cur_mutex);
# define INIT_TASK_GROUP_LOAD NICE_0_LOAD
#endif
+/*
+ * A weight of 0, 1 or ULONG_MAX can cause arithmetics problems.
+ * (The default weight is 1024 - so there's no practical
+ * limitation from this.)
+ */
#define MIN_SHARES 2
+#define MAX_SHARES (ULONG_MAX - 1)
static int init_task_group_load = INIT_TASK_GROUP_LOAD;
#endif
@@ -358,21 +357,9 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
#endif
}
-static inline void lock_doms_cur(void)
-{
- mutex_lock(&doms_cur_mutex);
-}
-
-static inline void unlock_doms_cur(void)
-{
- mutex_unlock(&doms_cur_mutex);
-}
-
#else
static inline void set_task_rq(struct task_struct *p, unsigned int cpu) { }
-static inline void lock_doms_cur(void) { }
-static inline void unlock_doms_cur(void) { }
#endif /* CONFIG_GROUP_SCHED */
@@ -560,13 +547,7 @@ struct rq {
unsigned long next_balance;
struct mm_struct *prev_mm;
- u64 clock, prev_clock_raw;
- s64 clock_max_delta;
-
- unsigned int clock_warps, clock_overflows, clock_underflows;
- u64 idle_clock;
- unsigned int clock_deep_idle_events;
- u64 tick_timestamp;
+ u64 clock;
atomic_t nr_iowait;
@@ -631,82 +612,6 @@ static inline int cpu_of(struct rq *rq)
#endif
}
-#ifdef CONFIG_NO_HZ
-static inline bool nohz_on(int cpu)
-{
- return tick_get_tick_sched(cpu)->nohz_mode != NOHZ_MODE_INACTIVE;
-}
-
-static inline u64 max_skipped_ticks(struct rq *rq)
-{
- return nohz_on(cpu_of(rq)) ? jiffies - rq->last_tick_seen + 2 : 1;
-}
-
-static inline void update_last_tick_seen(struct rq *rq)
-{
- rq->last_tick_seen = jiffies;
-}
-#else
-static inline u64 max_skipped_ticks(struct rq *rq)
-{
- return 1;
-}
-
-static inline void update_last_tick_seen(struct rq *rq)
-{
-}
-#endif
-
-/*
- * Update the per-runqueue clock, as finegrained as the platform can give
- * us, but without assuming monotonicity, etc.:
- */
-static void __update_rq_clock(struct rq *rq)
-{
- u64 prev_raw = rq->prev_clock_raw;
- u64 now = sched_clock();
- s64 delta = now - prev_raw;
- u64 clock = rq->clock;
-
-#ifdef CONFIG_SCHED_DEBUG
- WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
-#endif
- /*
- * Protect against sched_clock() occasionally going backwards:
- */
- if (unlikely(delta < 0)) {
- clock++;
- rq->clock_warps++;
- } else {
- /*
- * Catch too large forward jumps too:
- */
- u64 max_jump = max_skipped_ticks(rq) * TICK_NSEC;
- u64 max_time = rq->tick_timestamp + max_jump;
-
- if (unlikely(clock + delta > max_time)) {
- if (clock < max_time)
- clock = max_time;
- else
- clock++;
- rq->clock_overflows++;
- } else {
- if (unlikely(delta > rq->clock_max_delta))
- rq->clock_max_delta = delta;
- clock += delta;
- }
- }
-
- rq->prev_clock_raw = now;
- rq->clock = clock;
-}
-
-static void update_rq_clock(struct rq *rq)
-{
- if (likely(smp_processor_id() == cpu_of(rq)))
- __update_rq_clock(rq);
-}
-
/*
* The domain tree (rq->sd) is protected by RCU's quiescent state transition.
* See detach_destroy_domains: synchronize_sched for details.
@@ -722,6 +627,11 @@ static void update_rq_clock(struct rq *rq)
#define task_rq(p) cpu_rq(task_cpu(p))
#define cpu_curr(cpu) (cpu_rq(cpu)->curr)
+static inline void update_rq_clock(struct rq *rq)
+{
+ rq->clock = sched_clock_cpu(cpu_of(rq));
+}
+
/*
* Tunables that become constants when CONFIG_SCHED_DEBUG is off:
*/
@@ -757,14 +667,14 @@ const_debug unsigned int sysctl_sched_features =
#define SCHED_FEAT(name, enabled) \
#name ,
-__read_mostly char *sched_feat_names[] = {
+static __read_mostly char *sched_feat_names[] = {
#include "sched_features.h"
NULL
};
#undef SCHED_FEAT
-int sched_feat_open(struct inode *inode, struct file *filp)
+static int sched_feat_open(struct inode *inode, struct file *filp)
{
filp->private_data = inode->i_private;
return 0;
@@ -899,7 +809,7 @@ static inline u64 global_rt_runtime(void)
return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC;
}
-static const unsigned long long time_sync_thresh = 100000;
+unsigned long long time_sync_thresh = 100000;
static DEFINE_PER_CPU(unsigned long long, time_offset);
static DEFINE_PER_CPU(unsigned long long, prev_cpu_time);
@@ -913,11 +823,14 @@ static DEFINE_PER_CPU(unsigned long long, prev_cpu_time);
static DEFINE_SPINLOCK(time_sync_lock);
static unsigned long long prev_global_time;
-static unsigned long long __sync_cpu_clock(cycles_t time, int cpu)
+static unsigned long long __sync_cpu_clock(unsigned long long time, int cpu)
{
- unsigned long flags;
-
- spin_lock_irqsave(&time_sync_lock, flags);
+ /*
+ * We want this inlined, to not get tracer function calls
+ * in this critical section:
+ */
+ spin_acquire(&time_sync_lock.dep_map, 0, 0, _THIS_IP_);
+ __raw_spin_lock(&time_sync_lock.raw_lock);
if (time < prev_global_time) {
per_cpu(time_offset, cpu) += prev_global_time - time;
@@ -926,7 +839,8 @@ static unsigned long long __sync_cpu_clock(cycles_t time, int cpu)
prev_global_time = time;
}
- spin_unlock_irqrestore(&time_sync_lock, flags);
+ __raw_spin_unlock(&time_sync_lock.raw_lock);
+ spin_release(&time_sync_lock.dep_map, 1, _THIS_IP_);
return time;
}
@@ -934,8 +848,6 @@ static unsigned long long __sync_cpu_clock(cycles_t time, int cpu)
static unsigned long long __cpu_clock(int cpu)
{
unsigned long long now;
- unsigned long flags;
- struct rq *rq;
/*
* Only call sched_clock() if the scheduler has already been
@@ -944,11 +856,7 @@ static unsigned long long __cpu_clock(int cpu)
if (unlikely(!scheduler_running))
return 0;
- local_irq_save(flags);
- rq = cpu_rq(cpu);
- update_rq_clock(rq);
- now = rq->clock;
- local_irq_restore(flags);
+ now = sched_clock_cpu(cpu);
return now;
}
@@ -960,13 +868,18 @@ static unsigned long long __cpu_clock(int cpu)
unsigned long long cpu_clock(int cpu)
{
unsigned long long prev_cpu_time, time, delta_time;
+ unsigned long flags;
+ local_irq_save(flags);
prev_cpu_time = per_cpu(prev_cpu_time, cpu);
time = __cpu_clock(cpu) + per_cpu(time_offset, cpu);
delta_time = time-prev_cpu_time;
- if (unlikely(delta_time > time_sync_thresh))
+ if (unlikely(delta_time > time_sync_thresh)) {
time = __sync_cpu_clock(time, cpu);
+ per_cpu(prev_cpu_time, cpu) = time;
+ }
+ local_irq_restore(flags);
return time;
}
@@ -1117,43 +1030,6 @@ static struct rq *this_rq_lock(void)
return rq;
}
-/*
- * We are going deep-idle (irqs are disabled):
- */
-void sched_clock_idle_sleep_event(void)
-{
- struct rq *rq = cpu_rq(smp_processor_id());
-
- spin_lock(&rq->lock);
- __update_rq_clock(rq);
- spin_unlock(&rq->lock);
- rq->clock_deep_idle_events++;
-}
-EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
-
-/*
- * We just idled delta nanoseconds (called with irqs disabled):
- */
-void sched_clock_idle_wakeup_event(u64 delta_ns)
-{
- struct rq *rq = cpu_rq(smp_processor_id());
- u64 now = sched_clock();
-
- rq->idle_clock += delta_ns;
- /*
- * Override the previous timestamp and ignore all
- * sched_clock() deltas that occured while we idled,
- * and use the PM-provided delta_ns to advance the
- * rq clock:
- */
- spin_lock(&rq->lock);
- rq->prev_clock_raw = now;
- rq->clock += delta_ns;
- spin_unlock(&rq->lock);
- touch_softlockup_watchdog();
-}
-EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
-
static void __resched_task(struct task_struct *p, int tif_bit);
static inline void resched_task(struct task_struct *p)
@@ -1189,6 +1065,7 @@ static inline void resched_rq(struct rq *rq)
enum {
HRTICK_SET, /* re-programm hrtick_timer */
HRTICK_RESET, /* not a new slice */
+ HRTICK_BLOCK, /* stop hrtick operations */
};
/*
@@ -1200,6 +1077,8 @@ static inline int hrtick_enabled(struct rq *rq)
{
if (!sched_feat(HRTICK))
return 0;
+ if (unlikely(test_bit(HRTICK_BLOCK, &rq->hrtick_flags)))
+ return 0;
return hrtimer_is_hres_active(&rq->hrtick_timer);
}
@@ -1275,14 +1154,70 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer)
WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
spin_lock(&rq->lock);
- __update_rq_clock(rq);
+ update_rq_clock(rq);
rq->curr->sched_class->task_tick(rq, rq->curr, 1);
spin_unlock(&rq->lock);
return HRTIMER_NORESTART;
}
-static inline void init_rq_hrtick(struct rq *rq)
+static void hotplug_hrtick_disable(int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long flags;
+
+ spin_lock_irqsave(&rq->lock, flags);
+ rq->hrtick_flags = 0;
+ __set_bit(HRTICK_BLOCK, &rq->hrtick_flags);
+ spin_unlock_irqrestore(&rq->lock, flags);
+
+ hrtick_clear(rq);
+}
+
+static void hotplug_hrtick_enable(int cpu)
+{
+ struct rq *rq = cpu_rq(cpu);
+ unsigned long flags;
+
+ spin_lock_irqsave(&rq->lock, flags);
+ __clear_bit(HRTICK_BLOCK, &rq->hrtick_flags);
+ spin_unlock_irqrestore(&rq->lock, flags);
+}
+
+static int
+hotplug_hrtick(struct notifier_block *nfb, unsigned long action, void *hcpu)
+{
+ int cpu = (int)(long)hcpu;
+
+ switch (action) {
+ case CPU_UP_CANCELED:
+ case CPU_UP_CANCELED_FROZEN:
+ case CPU_DOWN_PREPARE:
+ case CPU_DOWN_PREPARE_FROZEN:
+ case CPU_DEAD:
+ case CPU_DEAD_FROZEN:
+ hotplug_hrtick_disable(cpu);
+ return NOTIFY_OK;
+
+ case CPU_UP_PREPARE:
+ case CPU_UP_PREPARE_FROZEN:
+ case CPU_DOWN_FAILED:
+ case CPU_DOWN_FAILED_FROZEN:
+ case CPU_ONLINE:
+ case CPU_ONLINE_FROZEN:
+ hotplug_hrtick_enable(cpu);
+ return NOTIFY_OK;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static void init_hrtick(void)
+{
+ hotcpu_notifier(hotplug_hrtick, 0);
+}
+
+static void init_rq_hrtick(struct rq *rq)
{
rq->hrtick_flags = 0;
hrtimer_init(&rq->hrtick_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
@@ -1319,6 +1254,10 @@ static inline void init_rq_hrtick(struct rq *rq)
void hrtick_resched(void)
{
}
+
+static inline void init_hrtick(void)
+{
+}
#endif
/*
@@ -1438,8 +1377,8 @@ calc_delta_mine(unsigned long delta_exec, unsigned long weight,
{
u64 tmp;
- if (unlikely(!lw->inv_weight))
- lw->inv_weight = (WMULT_CONST-lw->weight/2) / (lw->weight+1);
+ if (!lw->inv_weight)
+ lw->inv_weight = 1 + (WMULT_CONST-lw->weight/2)/(lw->weight+1);
tmp = (u64)delta_exec * weight;
/*
@@ -1748,6 +1687,8 @@ __update_group_shares_cpu(struct task_group *tg, struct sched_domain *sd,
if (shares < MIN_SHARES)
shares = MIN_SHARES;
+ else if (shares > MAX_SHARES)
+ shares = MAX_SHARES;
__set_se_shares(tg->se[tcpu], shares);
}
@@ -4339,8 +4280,10 @@ void account_system_time(struct task_struct *p, int hardirq_offset,
struct rq *rq = this_rq();
cputime64_t tmp;
- if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0))
- return account_guest_time(p, cputime);
+ if ((p->flags & PF_VCPU) && (irq_count() - hardirq_offset == 0)) {
+ account_guest_time(p, cputime);
+ return;
+ }
p->stime = cputime_add(p->stime, cputime);
@@ -4404,19 +4347,11 @@ void scheduler_tick(void)
int cpu = smp_processor_id();
struct rq *rq = cpu_rq(cpu);
struct task_struct *curr = rq->curr;
- u64 next_tick = rq->tick_timestamp + TICK_NSEC;
+
+ sched_clock_tick();
spin_lock(&rq->lock);
- __update_rq_clock(rq);
- /*
- * Let rq->clock advance by at least TICK_NSEC:
- */
- if (unlikely(rq->clock < next_tick)) {
- rq->clock = next_tick;
- rq->clock_underflows++;
- }
- rq->tick_timestamp = rq->clock;
- update_last_tick_seen(rq);
+ update_rq_clock(rq);
update_cpu_load(rq);
curr->sched_class->task_tick(rq, curr, 0);
spin_unlock(&rq->lock);
@@ -4570,7 +4505,7 @@ need_resched_nonpreemptible:
* Do the rq-clock update outside the rq lock:
*/
local_irq_disable();
- __update_rq_clock(rq);
+ update_rq_clock(rq);
spin_lock(&rq->lock);
clear_tsk_need_resched(prev);
@@ -4595,9 +4530,9 @@ need_resched_nonpreemptible:
prev->sched_class->put_prev_task(rq, prev);
next = pick_next_task(rq, prev);
- sched_info_switch(prev, next);
-
if (likely(prev != next)) {
+ sched_info_switch(prev, next);
+
rq->nr_switches++;
rq->curr = next;
++*switch_count;
@@ -7755,7 +7690,7 @@ void partition_sched_domains(int ndoms_new, cpumask_t *doms_new,
{
int i, j;
- lock_doms_cur();
+ mutex_lock(&sched_domains_mutex);
/* always unregister in case we don't destroy any domains */
unregister_sched_domain_sysctl();
@@ -7804,7 +7739,7 @@ match2:
register_sched_domain_sysctl();
- unlock_doms_cur();
+ mutex_unlock(&sched_domains_mutex);
}
#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
@@ -7813,8 +7748,10 @@ int arch_reinit_sched_domains(void)
int err;
get_online_cpus();
+ mutex_lock(&sched_domains_mutex);
detach_destroy_domains(&cpu_online_map);
err = arch_init_sched_domains(&cpu_online_map);
+ mutex_unlock(&sched_domains_mutex);
put_online_cpus();
return err;
@@ -7932,13 +7869,16 @@ void __init sched_init_smp(void)
BUG_ON(sched_group_nodes_bycpu == NULL);
#endif
get_online_cpus();
+ mutex_lock(&sched_domains_mutex);
arch_init_sched_domains(&cpu_online_map);
cpus_andnot(non_isolated_cpus, cpu_possible_map, cpu_isolated_map);
if (cpus_empty(non_isolated_cpus))
cpu_set(smp_processor_id(), non_isolated_cpus);
+ mutex_unlock(&sched_domains_mutex);
put_online_cpus();
/* XXX: Theoretical race here - CPU may be hotplugged now */
hotcpu_notifier(update_sched_domains, 0);
+ init_hrtick();
/* Move init over to a non-isolated CPU */
if (set_cpus_allowed_ptr(current, &non_isolated_cpus) < 0)
@@ -8025,7 +7965,7 @@ static void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
se->my_q = cfs_rq;
se->load.weight = tg->shares;
- se->load.inv_weight = div64_u64(1ULL<<32, se->load.weight);
+ se->load.inv_weight = 0;
se->parent = parent;
}
#endif
@@ -8149,8 +8089,6 @@ void __init sched_init(void)
spin_lock_init(&rq->lock);
lockdep_set_class(&rq->lock, &rq->rq_lock_key);
rq->nr_running = 0;
- rq->clock = 1;
- update_last_tick_seen(rq);
init_cfs_rq(&rq->cfs, rq);
init_rt_rq(&rq->rt, rq);
#ifdef CONFIG_FAIR_GROUP_SCHED
@@ -8294,6 +8232,7 @@ EXPORT_SYMBOL(__might_sleep);
static void normalize_task(struct rq *rq, struct task_struct *p)
{
int on_rq;
+
update_rq_clock(rq);
on_rq = p->se.on_rq;
if (on_rq)
@@ -8325,7 +8264,6 @@ void normalize_rt_tasks(void)
p->se.sleep_start = 0;
p->se.block_start = 0;
#endif
- task_rq(p)->clock = 0;
if (!rt_task(p)) {
/*
@@ -8692,7 +8630,7 @@ static void __set_se_shares(struct sched_entity *se, unsigned long shares)
dequeue_entity(cfs_rq, se, 0);
se->load.weight = shares;
- se->load.inv_weight = div64_u64((1ULL<<32), shares);
+ se->load.inv_weight = 0;
if (on_rq)
enqueue_entity(cfs_rq, se, 0);
@@ -8722,13 +8660,10 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
if (!tg->se[0])
return -EINVAL;
- /*
- * A weight of 0 or 1 can cause arithmetics problems.
- * (The default weight is 1024 - so there's no practical
- * limitation from this.)
- */
if (shares < MIN_SHARES)
shares = MIN_SHARES;
+ else if (shares > MAX_SHARES)
+ shares = MAX_SHARES;
mutex_lock(&shares_mutex);
if (tg->shares == shares)
@@ -8753,7 +8688,7 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares)
* force a rebalance
*/
cfs_rq_set_shares(tg->cfs_rq[i], 0);
- set_se_shares(tg->se[i], shares/nr_cpu_ids);
+ set_se_shares(tg->se[i], shares);
}
/*
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
new file mode 100644
index 0000000..9c597e3
--- /dev/null
+++ b/kernel/sched_clock.c
@@ -0,0 +1,236 @@
+/*
+ * sched_clock for unstable cpu clocks
+ *
+ * Copyright (C) 2008 Red Hat, Inc., Peter Zijlstra <pzijlstr@xxxxxxxxxx>
+ *
+ * Based on code by:
+ * Ingo Molnar <mingo@xxxxxxxxxx>
+ * Guillaume Chazarain <guichaz@xxxxxxxxx>
+ *
+ * Create a semi stable clock from a mixture of other events, including:
+ * - gtod
+ * - jiffies
+ * - sched_clock()
+ * - explicit idle events
+ *
+ * We use gtod as base and the unstable clock deltas. The deltas are filtered,
+ * making it monotonic and keeping it within an expected window. This window
+ * is set up using jiffies.
+ *
+ * Furthermore, explicit sleep and wakeup hooks allow us to account for time
+ * that is otherwise invisible (TSC gets stopped).
+ *
+ * The clock: sched_clock_cpu() is monotonic per cpu, and should be somewhat
+ * consistent between cpus (never more than 1 jiffies difference).
+ */
+#include <linux/sched.h>
+#include <linux/percpu.h>
+#include <linux/spinlock.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
+
+
+#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
+
+struct sched_clock_data {
+ /*
+ * Raw spinlock - this is a special case: this might be called
+ * from within instrumentation code so we dont want to do any
+ * instrumentation ourselves.
+ */
+ raw_spinlock_t lock;
+
+ unsigned long prev_jiffies;
+ u64 prev_raw;
+ u64 tick_raw;
+ u64 tick_gtod;
+ u64 clock;
+};
+
+static DEFINE_PER_CPU_SHARED_ALIGNED(struct sched_clock_data, sched_clock_data);
+
+static inline struct sched_clock_data *this_scd(void)
+{
+ return &__get_cpu_var(sched_clock_data);
+}
+
+static inline struct sched_clock_data *cpu_sdc(int cpu)
+{
+ return &per_cpu(sched_clock_data, cpu);
+}
+
+void sched_clock_init(void)
+{
+ u64 ktime_now = ktime_to_ns(ktime_get());
+ u64 now = 0;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ struct sched_clock_data *scd = cpu_sdc(cpu);
+
+ scd->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
+ scd->prev_jiffies = jiffies;
+ scd->prev_raw = now;
+ scd->tick_raw = now;
+ scd->tick_gtod = ktime_now;
+ scd->clock = ktime_now;
+ }
+}
+
+/*
+ * update the percpu scd from the raw @now value
+ *
+ * - filter out backward motion
+ * - use jiffies to generate a min,max window to clip the raw values
+ */
+static void __update_sched_clock(struct sched_clock_data *scd, u64 now)
+{
+ unsigned long now_jiffies = jiffies;
+ long delta_jiffies = now_jiffies - scd->prev_jiffies;
+ u64 clock = scd->clock;
+ u64 min_clock, max_clock;
+ s64 delta = now - scd->prev_raw;
+
+ WARN_ON_ONCE(!irqs_disabled());
+ min_clock = scd->tick_gtod + delta_jiffies * TICK_NSEC;
+
+ if (unlikely(delta < 0)) {
+ clock++;
+ goto out;
+ }
+
+ max_clock = min_clock + TICK_NSEC;
+
+ if (unlikely(clock + delta > max_clock)) {
+ if (clock < max_clock)
+ clock = max_clock;
+ else
+ clock++;
+ } else {
+ clock += delta;
+ }
+
+ out:
+ if (unlikely(clock < min_clock))
+ clock = min_clock;
+
+ scd->prev_raw = now;
+ scd->prev_jiffies = now_jiffies;
+ scd->clock = clock;
+}
+
+static void lock_double_clock(struct sched_clock_data *data1,
+ struct sched_clock_data *data2)
+{
+ if (data1 < data2) {
+ __raw_spin_lock(&data1->lock);
+ __raw_spin_lock(&data2->lock);
+ } else {
+ __raw_spin_lock(&data2->lock);
+ __raw_spin_lock(&data1->lock);
+ }
+}
+
+u64 sched_clock_cpu(int cpu)
+{
+ struct sched_clock_data *scd = cpu_sdc(cpu);
+ u64 now, clock;
+
+ WARN_ON_ONCE(!irqs_disabled());
+ now = sched_clock();
+
+ if (cpu != raw_smp_processor_id()) {
+ /*
+ * in order to update a remote cpu's clock based on our
+ * unstable raw time rebase it against:
+ * tick_raw (offset between raw counters)
+ * tick_gotd (tick offset between cpus)
+ */
+ struct sched_clock_data *my_scd = this_scd();
+
+ lock_double_clock(scd, my_scd);
+
+ now -= my_scd->tick_raw;
+ now += scd->tick_raw;
+
+ now -= my_scd->tick_gtod;
+ now += scd->tick_gtod;
+
+ __raw_spin_unlock(&my_scd->lock);
+ } else {
+ __raw_spin_lock(&scd->lock);
+ }
+
+ __update_sched_clock(scd, now);
+ clock = scd->clock;
+
+ __raw_spin_unlock(&scd->lock);
+
+ return clock;
+}
+
+void sched_clock_tick(void)
+{
+ struct sched_clock_data *scd = this_scd();
+ u64 now, now_gtod;
+
+ WARN_ON_ONCE(!irqs_disabled());
+
+ now = sched_clock();
+ now_gtod = ktime_to_ns(ktime_get());
+
+ __raw_spin_lock(&scd->lock);
+ __update_sched_clock(scd, now);
+ /*
+ * update tick_gtod after __update_sched_clock() because that will
+ * already observe 1 new jiffy; adding a new tick_gtod to that would
+ * increase the clock 2 jiffies.
+ */
+ scd->tick_raw = now;
+ scd->tick_gtod = now_gtod;
+ __raw_spin_unlock(&scd->lock);
+}
+
+/*
+ * We are going deep-idle (irqs are disabled):
+ */
+void sched_clock_idle_sleep_event(void)
+{
+ sched_clock_cpu(smp_processor_id());
+}
+EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
+
+/*
+ * We just idled delta nanoseconds (called with irqs disabled):
+ */
+void sched_clock_idle_wakeup_event(u64 delta_ns)
+{
+ struct sched_clock_data *scd = this_scd();
+ u64 now = sched_clock();
+
+ /*
+ * Override the previous timestamp and ignore all
+ * sched_clock() deltas that occured while we idled,
+ * and use the PM-provided delta_ns to advance the
+ * rq clock:
+ */
+ __raw_spin_lock(&scd->lock);
+ scd->prev_raw = now;
+ scd->clock += delta_ns;
+ __raw_spin_unlock(&scd->lock);
+
+ touch_softlockup_watchdog();
+}
+EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);
+
+#endif
+
+/*
+ * Scheduler clock - returns current time in nanosec units.
+ * This is default implementation.
+ * Architectures and sub-architectures can override this.
+ */
+unsigned long long __attribute__((weak)) sched_clock(void)
+{
+ return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
+}
diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 6b4a125..5f06118 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -204,13 +204,6 @@ static void print_cpu(struct seq_file *m, int cpu)
PN(next_balance);
P(curr->pid);
PN(clock);
- PN(idle_clock);
- PN(prev_clock_raw);
- P(clock_warps);
- P(clock_overflows);
- P(clock_underflows);
- P(clock_deep_idle_events);
- PN(clock_max_delta);
P(cpu_load[0]);
P(cpu_load[1]);
P(cpu_load[2]);
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 89fa32b..c863663 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -682,6 +682,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
* Update run-time statistics of the 'current'.
*/
update_curr(cfs_rq);
+ account_entity_enqueue(cfs_rq, se);
if (wakeup) {
place_entity(cfs_rq, se, 0);
@@ -692,7 +693,6 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int wakeup)
check_spread(cfs_rq, se);
if (se != cfs_rq->curr)
__enqueue_entity(cfs_rq, se);
- account_entity_enqueue(cfs_rq, se);
}
static void update_avg(u64 *avg, u64 sample)
@@ -841,8 +841,10 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
* queued ticks are scheduled to match the slice, so don't bother
* validating it and just reschedule.
*/
- if (queued)
- return resched_task(rq_of(cfs_rq)->curr);
+ if (queued) {
+ resched_task(rq_of(cfs_rq)->curr);
+ return;
+ }
/*
* don't let the period tick interfere with the hrtick preemption
*/
@@ -957,7 +959,7 @@ static void yield_task_fair(struct rq *rq)
return;
if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) {
- __update_rq_clock(rq);
+ update_rq_clock(rq);
/*
* Update run-time statistics of the 'current'.
*/
@@ -1007,7 +1009,7 @@ static int wake_idle(int cpu, struct task_struct *p)
* sibling runqueue info. This will avoid the checks and cache miss
* penalities associated with that.
*/
- if (idle_cpu(cpu) || cpu_rq(cpu)->nr_running > 1)
+ if (idle_cpu(cpu) || cpu_rq(cpu)->cfs.nr_running > 1)
return cpu;
for_each_domain(cpu, sd) {
@@ -1611,30 +1613,6 @@ static const struct sched_class fair_sched_class = {
};
#ifdef CONFIG_SCHED_DEBUG
-static void
-print_cfs_rq_tasks(struct seq_file *m, struct cfs_rq *cfs_rq, int depth)
-{
- struct sched_entity *se;
-
- if (!cfs_rq)
- return;
-
- list_for_each_entry_rcu(se, &cfs_rq->tasks, group_node) {
- int i;
-
- for (i = depth; i; i--)
- seq_puts(m, " ");
-
- seq_printf(m, "%lu %s %lu\n",
- se->load.weight,
- entity_is_task(se) ? "T" : "G",
- calc_delta_weight(SCHED_LOAD_SCALE, se)
- );
- if (!entity_is_task(se))
- print_cfs_rq_tasks(m, group_cfs_rq(se), depth + 1);
- }
-}
-
static void print_cfs_stats(struct seq_file *m, int cpu)
{
struct cfs_rq *cfs_rq;
@@ -1642,9 +1620,6 @@ static void print_cfs_stats(struct seq_file *m, int cpu)
rcu_read_lock();
for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
print_cfs_rq(m, cpu, cfs_rq);
-
- seq_printf(m, "\nWeight tree:\n");
- print_cfs_rq_tasks(m, &cpu_rq(cpu)->cfs, 1);
rcu_read_unlock();
}
#endif
diff --git a/kernel/sched_idletask.c b/kernel/sched_idletask.c
index 2bcafa3..3a4f92d 100644
--- a/kernel/sched_idletask.c
+++ b/kernel/sched_idletask.c
@@ -99,7 +99,7 @@ static void prio_changed_idle(struct rq *rq, struct task_struct *p,
/*
* Simple, special scheduling class for the per-CPU idle tasks:
*/
-const struct sched_class idle_sched_class = {
+static const struct sched_class idle_sched_class = {
/* .next is NULL */
/* no enqueue/yield_task for idle tasks */
diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c
index c2730a5..060e87b 100644
--- a/kernel/sched_rt.c
+++ b/kernel/sched_rt.c
@@ -1098,11 +1098,14 @@ static void post_schedule_rt(struct rq *rq)
}
}
-
+/*
+ * If we are not running and we are not going to reschedule soon, we should
+ * try to push tasks away now
+ */
static void task_wake_up_rt(struct rq *rq, struct task_struct *p)
{
if (!task_running(rq, p) &&
- (p->prio >= rq->rt.highest_prio) &&
+ !test_tsk_need_resched(rq->curr) &&
rq->rt.overloaded)
push_rt_tasks(rq);
}
@@ -1309,7 +1312,7 @@ static void set_curr_task_rt(struct rq *rq)
p->se.exec_start = rq->clock;
}
-const struct sched_class rt_sched_class = {
+static const struct sched_class rt_sched_class = {
.next = &fair_sched_class,
.enqueue_task = enqueue_task_rt,
.dequeue_task = dequeue_task_rt,
--
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