Skip to content

Commit

Permalink
Merge branch 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/…
Browse files Browse the repository at this point in the history 
…linux/kernel/git/tip/linux-2.6-tip

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched, cpu hotplug: fix set_cpus_allowed() use in hotplug callbacks
  sched: fix mysql+oltp regression
  sched_clock: delay using sched_clock()
  sched clock: couple local and remote clocks
  sched clock: simplify __update_sched_clock()
  sched: eliminate scd->prev_raw
  sched clock: clean up sched_clock_cpu()
  sched clock: revert various sched_clock() changes
  sched: move sched_clock before first use
  sched: test runtime rather than period in global_rt_runtime()
  sched: fix SCHED_HRTICK dependency
  sched: fix warning in hrtick_start_fair()
  • Loading branch information
Linus Torvalds committed Aug 11, 2008
2 parents 67a077d + e26b33e commit 1ea2950
Show file tree
Hide file tree
Showing 7 changed files with 77 additions and 164 deletions.
31 changes: 4 additions & 27 deletions include/linux/sched.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1551,16 +1551,10 @@ 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();
}
extern void sched_clock_init(void);
extern u64 sched_clock_cpu(int cpu);

#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
static inline void sched_clock_tick(void)
{
}
Expand All @@ -1572,28 +1566,11 @@ static inline void sched_clock_idle_sleep_event(void)
static inline void sched_clock_idle_wakeup_event(u64 delta_ns)
{
}

#ifdef CONFIG_NO_HZ
static inline void sched_clock_tick_stop(int cpu)
{
}

static inline void sched_clock_tick_start(int cpu)
{
}
#endif

#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */
extern void sched_clock_init(void);
extern u64 sched_clock_cpu(int cpu);
#else
extern void sched_clock_tick(void);
extern void sched_clock_idle_sleep_event(void);
extern void sched_clock_idle_wakeup_event(u64 delta_ns);
#ifdef CONFIG_NO_HZ
extern void sched_clock_tick_stop(int cpu);
extern void sched_clock_tick_start(int cpu);
#endif
#endif /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */

/*
* For kernel-internal use: high-speed (but slightly incorrect) per-cpu
Expand Down
2 changes: 1 addition & 1 deletion kernel/Kconfig.hz
View file
Original file line number Diff line number Diff line change
Expand Up @@ -55,4 +55,4 @@ config HZ
default 1000 if HZ_1000

config SCHED_HRTICK
def_bool HIGH_RES_TIMERS && USE_GENERIC_SMP_HELPERS
def_bool HIGH_RES_TIMERS && (!SMP || USE_GENERIC_SMP_HELPERS)
5 changes: 2 additions & 3 deletions kernel/cpu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -349,6 +349,8 @@ static int __cpuinit _cpu_up(unsigned int cpu, int tasks_frozen)
goto out_notify;
BUG_ON(!cpu_online(cpu));

cpu_set(cpu, cpu_active_map);

/* Now call notifier in preparation. */
raw_notifier_call_chain(&cpu_chain, CPU_ONLINE | mod, hcpu);

Expand Down Expand Up @@ -383,9 +385,6 @@ int __cpuinit cpu_up(unsigned int cpu)

err = _cpu_up(cpu, 0);

if (cpu_online(cpu))
cpu_set(cpu, cpu_active_map);

out:
cpu_maps_update_done();
return err;
Expand Down
2 changes: 1 addition & 1 deletion kernel/sched.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -833,7 +833,7 @@ static inline u64 global_rt_period(void)

static inline u64 global_rt_runtime(void)
{
if (sysctl_sched_rt_period < 0)
if (sysctl_sched_rt_runtime < 0)
return RUNTIME_INF;

return (u64)sysctl_sched_rt_runtime * NSEC_PER_USEC;
Expand Down
178 changes: 56 additions & 122 deletions kernel/sched_clock.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -32,13 +32,19 @@
#include <linux/ktime.h>
#include <linux/module.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);
}

#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
static __read_mostly int sched_clock_running;

#define MULTI_SHIFT 15
/* Max is double, Min is 1/2 */
#define MAX_MULTI (2LL << MULTI_SHIFT)
#define MIN_MULTI (1LL << (MULTI_SHIFT-1))
#ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

struct sched_clock_data {
/*
Expand All @@ -49,14 +55,9 @@ struct sched_clock_data {
raw_spinlock_t lock;

unsigned long tick_jiffies;
u64 prev_raw;
u64 tick_raw;
u64 tick_gtod;
u64 clock;
s64 multi;
#ifdef CONFIG_NO_HZ
int check_max;
#endif
};

static DEFINE_PER_CPU_SHARED_ALIGNED(struct sched_clock_data, sched_clock_data);
Expand All @@ -71,8 +72,6 @@ static inline struct sched_clock_data *cpu_sdc(int cpu)
return &per_cpu(sched_clock_data, cpu);
}

static __read_mostly int sched_clock_running;

void sched_clock_init(void)
{
u64 ktime_now = ktime_to_ns(ktime_get());
Expand All @@ -84,90 +83,39 @@ void sched_clock_init(void)

scd->lock = (raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;
scd->tick_jiffies = now_jiffies;
scd->prev_raw = 0;
scd->tick_raw = 0;
scd->tick_gtod = ktime_now;
scd->clock = ktime_now;
scd->multi = 1 << MULTI_SHIFT;
#ifdef CONFIG_NO_HZ
scd->check_max = 1;
#endif
}

sched_clock_running = 1;
}

#ifdef CONFIG_NO_HZ
/*
* The dynamic ticks makes the delta jiffies inaccurate. This
* prevents us from checking the maximum time update.
* Disable the maximum check during stopped ticks.
*/
void sched_clock_tick_stop(int cpu)
{
struct sched_clock_data *scd = cpu_sdc(cpu);

scd->check_max = 0;
}

void sched_clock_tick_start(int cpu)
{
struct sched_clock_data *scd = cpu_sdc(cpu);

scd->check_max = 1;
}

static int check_max(struct sched_clock_data *scd)
{
return scd->check_max;
}
#else
static int check_max(struct sched_clock_data *scd)
{
return 1;
}
#endif /* CONFIG_NO_HZ */

/*
* 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, u64 *time)
static u64 __update_sched_clock(struct sched_clock_data *scd, u64 now)
{
unsigned long now_jiffies = jiffies;
long delta_jiffies = now_jiffies - scd->tick_jiffies;
u64 clock = scd->clock;
u64 min_clock, max_clock;
s64 delta = now - scd->prev_raw;
s64 delta = now - scd->tick_raw;

WARN_ON_ONCE(!irqs_disabled());

/*
* At schedule tick the clock can be just under the gtod. We don't
* want to push it too prematurely.
*/
min_clock = scd->tick_gtod + (delta_jiffies * TICK_NSEC);
if (min_clock > TICK_NSEC)
min_clock -= TICK_NSEC / 2;
min_clock = scd->tick_gtod + delta_jiffies * TICK_NSEC;

if (unlikely(delta < 0)) {
clock++;
goto out;
}

/*
* The clock must stay within a jiffie of the gtod.
* But since we may be at the start of a jiffy or the end of one
* we add another jiffy buffer.
*/
max_clock = scd->tick_gtod + (2 + delta_jiffies) * TICK_NSEC;

delta *= scd->multi;
delta >>= MULTI_SHIFT;
max_clock = min_clock + TICK_NSEC;

if (unlikely(clock + delta > max_clock) && check_max(scd)) {
if (unlikely(clock + delta > max_clock)) {
if (clock < max_clock)
clock = max_clock;
else
Expand All @@ -180,12 +128,10 @@ static void __update_sched_clock(struct sched_clock_data *scd, u64 now, u64 *tim
if (unlikely(clock < min_clock))
clock = min_clock;

if (time)
*time = clock;
else {
scd->prev_raw = now;
scd->clock = clock;
}
scd->tick_jiffies = now_jiffies;
scd->clock = clock;

return clock;
}

static void lock_double_clock(struct sched_clock_data *data1,
Expand All @@ -203,7 +149,7 @@ static void lock_double_clock(struct sched_clock_data *data1,
u64 sched_clock_cpu(int cpu)
{
struct sched_clock_data *scd = cpu_sdc(cpu);
u64 now, clock;
u64 now, clock, this_clock, remote_clock;

if (unlikely(!sched_clock_running))
return 0ull;
Expand All @@ -212,43 +158,44 @@ u64 sched_clock_cpu(int cpu)
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;
this_clock = __update_sched_clock(my_scd, now);
remote_clock = scd->clock;

now += my_scd->tick_gtod;
now -= scd->tick_gtod;
/*
* Use the opportunity that we have both locks
* taken to couple the two clocks: we take the
* larger time as the latest time for both
* runqueues. (this creates monotonic movement)
*/
if (likely(remote_clock < this_clock)) {
clock = this_clock;
scd->clock = clock;
} else {
/*
* Should be rare, but possible:
*/
clock = remote_clock;
my_scd->clock = remote_clock;
}

__raw_spin_unlock(&my_scd->lock);

__update_sched_clock(scd, now, &clock);

__raw_spin_unlock(&scd->lock);

} else {
__raw_spin_lock(&scd->lock);
__update_sched_clock(scd, now, NULL);
clock = scd->clock;
__raw_spin_unlock(&scd->lock);
clock = __update_sched_clock(scd, now);
}

__raw_spin_unlock(&scd->lock);

return clock;
}

void sched_clock_tick(void)
{
struct sched_clock_data *scd = this_scd();
unsigned long now_jiffies = jiffies;
s64 mult, delta_gtod, delta_raw;
u64 now, now_gtod;

if (unlikely(!sched_clock_running))
Expand All @@ -260,29 +207,14 @@ void sched_clock_tick(void)
now = sched_clock();

__raw_spin_lock(&scd->lock);
__update_sched_clock(scd, now, NULL);
__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.
*/
delta_gtod = now_gtod - scd->tick_gtod;
delta_raw = now - scd->tick_raw;

if ((long)delta_raw > 0) {
mult = delta_gtod << MULTI_SHIFT;
do_div(mult, delta_raw);
scd->multi = mult;
if (scd->multi > MAX_MULTI)
scd->multi = MAX_MULTI;
else if (scd->multi < MIN_MULTI)
scd->multi = MIN_MULTI;
} else
scd->multi = 1 << MULTI_SHIFT;

scd->tick_raw = now;
scd->tick_gtod = now_gtod;
scd->tick_jiffies = now_jiffies;
__raw_spin_unlock(&scd->lock);
}

Expand All @@ -301,7 +233,6 @@ EXPORT_SYMBOL_GPL(sched_clock_idle_sleep_event);
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
Expand All @@ -310,27 +241,30 @@ void sched_clock_idle_wakeup_event(u64 delta_ns)
* rq clock:
*/
__raw_spin_lock(&scd->lock);
scd->prev_raw = now;
scd->clock += delta_ns;
scd->multi = 1 << MULTI_SHIFT;
__raw_spin_unlock(&scd->lock);

touch_softlockup_watchdog();
}
EXPORT_SYMBOL_GPL(sched_clock_idle_wakeup_event);

#endif
#else /* CONFIG_HAVE_UNSTABLE_SCHED_CLOCK */

/*
* 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)
void sched_clock_init(void)
{
return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
sched_clock_running = 1;
}

u64 sched_clock_cpu(int cpu)
{
if (unlikely(!sched_clock_running))
return 0;

return sched_clock();
}

#endif

unsigned long long cpu_clock(int cpu)
{
unsigned long long clock;
Expand Down
Loading

0 comments on commit 1ea2950

Please sign in to comment.