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Merge branch 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 

* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  timers, init: Limit the number of per cpu calibration bootup messages
  posix-cpu-timers: optimize and document timer_create callback
  clockevents: Add missing include to pacify sparse
  x86: vmiclock: Fix printk format
  x86: Fix printk format due to variable type change
  sparc: fix printk for change of variable type
  clocksource/events: Fix fallout of generic code changes
  nohz: Allow 32-bit machines to sleep for more than 2.15 seconds
  nohz: Track last do_timer() cpu
  nohz: Prevent clocksource wrapping during idle
  nohz: Type cast printk argument
  mips: Use generic mult/shift factor calculation for clocks
  clocksource: Provide a generic mult/shift factor calculation
  clockevents: Use u32 for mult and shift factors
  nohz: Introduce arch_needs_cpu
  nohz: Reuse ktime in sub-functions of tick_check_idle.
  time: Remove xtime_cache
  time: Implement logarithmic time accumulation
This commit is contained in:
Linus Torvalds 2009-12-08 19:27:08 -08:00
parent 849e8dea09 feae3203d7
commit 60d8ce2cd6
26 changed files with 353 additions and 178 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/mips/include/asm/time.h
View File

@ -84,8 +84,16 @@ static inline int init_mips_clocksource(void)
#endif
}
extern void clocksource_set_clock(struct clocksource *cs, unsigned int clock);
extern void clockevent_set_clock(struct clock_event_device *cd,
unsigned int clock);
static inline void clocksource_set_clock(struct clocksource *cs,
unsigned int clock)
{
clocksource_calc_mult_shift(cs, clock, 4);
}
static inline void clockevent_set_clock(struct clock_event_device *cd,
unsigned int clock)
{
clockevents_calc_mult_shift(cd, clock, 4);
}
#endif /* _ASM_TIME_H */

33
arch/mips/kernel/time.c
View File

@ -71,39 +71,6 @@ EXPORT_SYMBOL(perf_irq);
unsigned int mips_hpt_frequency;
void __init clocksource_set_clock(struct clocksource *cs, unsigned int clock)
{
u64 temp;
u32 shift;
/* Find a shift value */
for (shift = 32; shift > 0; shift--) {
temp = (u64) NSEC_PER_SEC << shift;
do_div(temp, clock);
if ((temp >> 32) == 0)
break;
}
cs->shift = shift;
cs->mult = (u32) temp;
}
void __cpuinit clockevent_set_clock(struct clock_event_device *cd,
unsigned int clock)
{
u64 temp;
u32 shift;
/* Find a shift value */
for (shift = 32; shift > 0; shift--) {
temp = (u64) clock << shift;
do_div(temp, NSEC_PER_SEC);
if ((temp >> 32) == 0)
break;
}
cd->shift = shift;
cd->mult = (u32) temp;
}
/*
* This function exists in order to cause an error due to a duplicate
* definition if platform code should have its own implementation. The hook

2
arch/powerpc/kernel/time.c
View File

@ -924,7 +924,7 @@ static void register_decrementer_clockevent(int cpu)
*dec = decrementer_clockevent;
dec->cpumask = cpumask_of(cpu);
printk(KERN_DEBUG "clockevent: %s mult[%lx] shift[%d] cpu[%d]\n",
printk(KERN_DEBUG "clockevent: %s mult[%x] shift[%d] cpu[%d]\n",
dec->name, dec->mult, dec->shift, cpu);
clockevents_register_device(dec);

8
arch/s390/include/asm/cputime.h
View File

@ -183,6 +183,7 @@ struct s390_idle_data {
unsigned long long idle_count;
unsigned long long idle_enter;
unsigned long long idle_time;
int nohz_delay;
};
DECLARE_PER_CPU(struct s390_idle_data, s390_idle);
@ -198,4 +199,11 @@ static inline void s390_idle_check(void)
vtime_start_cpu();
}
static inline int s390_nohz_delay(int cpu)
{
return per_cpu(s390_idle, cpu).nohz_delay != 0;
}
#define arch_needs_cpu(cpu) s390_nohz_delay(cpu)
#endif /* _S390_CPUTIME_H */

2
arch/s390/kernel/s390_ext.c
View File

@ -126,6 +126,8 @@ void __irq_entry do_extint(struct pt_regs *regs, unsigned short code)
/* Serve timer interrupts first. */
clock_comparator_work();
kstat_cpu(smp_processor_id()).irqs[EXTERNAL_INTERRUPT]++;
if (code != 0x1004)
__get_cpu_var(s390_idle).nohz_delay = 1;
index = ext_hash(code);
for (p = ext_int_hash[index]; p; p = p->next) {
if (likely(p->code == code))

2
arch/s390/kernel/vtime.c
View File

@ -167,6 +167,8 @@ void vtime_stop_cpu(void)
/* Wait for external, I/O or machine check interrupt. */
psw.mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_IO | PSW_MASK_EXT;
idle->nohz_delay = 0;
/* Check if the CPU timer needs to be reprogrammed. */
if (vq->do_spt) {
__u64 vmax = VTIMER_MAX_SLICE;

2
arch/sparc/kernel/time_64.c
View File

@ -847,7 +847,7 @@ void __init time_init(void)
sparc64_clockevent.min_delta_ns =
clockevent_delta2ns(0xF, &sparc64_clockevent);
printk("clockevent: mult[%lx] shift[%d]\n",
printk("clockevent: mult[%ux] shift[%d]\n",
sparc64_clockevent.mult, sparc64_clockevent.shift);
setup_sparc64_timer();

2
arch/x86/kernel/apic/apic.c
View File

@ -647,7 +647,7 @@ static int __init calibrate_APIC_clock(void)
calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
apic_printk(APIC_VERBOSE, "..... mult: %ld\n", lapic_clockevent.mult);
apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
calibration_result);

2
arch/x86/kernel/vmiclock_32.c
View File

@ -226,7 +226,7 @@ static void __devinit vmi_time_init_clockevent(void)
evt->min_delta_ns = clockevent_delta2ns(1, evt);
evt->cpumask = cpumask_of(cpu);
printk(KERN_WARNING "vmi: registering clock event %s. mult=%lu shift=%u\n",
printk(KERN_WARNING "vmi: registering clock event %s. mult=%u shift=%u\n",
evt->name, evt->mult, evt->shift);
clockevents_register_device(evt);
}

1
drivers/s390/cio/cio.c
View File

@ -618,6 +618,7 @@ void __irq_entry do_IRQ(struct pt_regs *regs)
old_regs = set_irq_regs(regs);
s390_idle_check();
irq_enter();
__get_cpu_var(s390_idle).nohz_delay = 1;
if (S390_lowcore.int_clock >= S390_lowcore.clock_comparator)
/* Serve timer interrupts first. */
clock_comparator_work();

19
include/linux/clockchips.h
View File

@ -77,10 +77,10 @@ enum clock_event_nofitiers {
struct clock_event_device {
const char *name;
unsigned int features;
unsigned long max_delta_ns;
unsigned long min_delta_ns;
unsigned long mult;
int shift;
u64 max_delta_ns;
u64 min_delta_ns;
u32 mult;
u32 shift;
int rating;
int irq;
const struct cpumask *cpumask;
@ -116,8 +116,8 @@ static inline unsigned long div_sc(unsigned long ticks, unsigned long nsec,
}
/* Clock event layer functions */
extern unsigned long clockevent_delta2ns(unsigned long latch,
struct clock_event_device *evt);
extern u64 clockevent_delta2ns(unsigned long latch,
struct clock_event_device *evt);
extern void clockevents_register_device(struct clock_event_device *dev);
extern void clockevents_exchange_device(struct clock_event_device *old,
@ -130,6 +130,13 @@ extern int clockevents_program_event(struct clock_event_device *dev,
extern void clockevents_handle_noop(struct clock_event_device *dev);
static inline void
clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 minsec)
{
return clocks_calc_mult_shift(&ce->mult, &ce->shift, NSEC_PER_SEC,
freq, minsec);
}
#ifdef CONFIG_GENERIC_CLOCKEVENTS
extern void clockevents_notify(unsigned long reason, void *arg);
#else

12
include/linux/clocksource.h
View File

@ -151,6 +151,7 @@ extern u64 timecounter_cyc2time(struct timecounter *tc,
* subtraction of non 64 bit counters
* @mult: cycle to nanosecond multiplier
* @shift: cycle to nanosecond divisor (power of two)
* @max_idle_ns: max idle time permitted by the clocksource (nsecs)
* @flags: flags describing special properties
* @vread: vsyscall based read
* @resume: resume function for the clocksource, if necessary
@ -168,6 +169,7 @@ struct clocksource {
cycle_t mask;
u32 mult;
u32 shift;
u64 max_idle_ns;
unsigned long flags;
cycle_t (*vread)(void);
void (*resume)(void);
@ -279,6 +281,16 @@ extern void clocksource_resume(void);
extern struct clocksource * __init __weak clocksource_default_clock(void);
extern void clocksource_mark_unstable(struct clocksource *cs);
extern void
clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
static inline void
clocksource_calc_mult_shift(struct clocksource *cs, u32 freq, u32 minsec)
{
return clocks_calc_mult_shift(&cs->mult, &cs->shift, freq,
NSEC_PER_SEC, minsec);
}
#ifdef CONFIG_GENERIC_TIME_VSYSCALL
extern void update_vsyscall(struct timespec *ts, struct clocksource *c);
extern void update_vsyscall_tz(void);

5
include/linux/tick.h
View File

@ -43,6 +43,7 @@ enum tick_nohz_mode {
* @idle_exittime: Time when the idle state was left
* @idle_sleeptime: Sum of the time slept in idle with sched tick stopped
* @sleep_length: Duration of the current idle sleep
* @do_timer_lst: CPU was the last one doing do_timer before going idle
*/
struct tick_sched {
struct hrtimer sched_timer;
@ -64,6 +65,7 @@ struct tick_sched {
unsigned long last_jiffies;
unsigned long next_jiffies;
ktime_t idle_expires;
int do_timer_last;
};
extern void __init tick_init(void);
@ -98,6 +100,9 @@ extern int tick_check_oneshot_change(int allow_nohz);
extern struct tick_sched *tick_get_tick_sched(int cpu);
extern void tick_check_idle(int cpu);
extern int tick_oneshot_mode_active(void);
# ifndef arch_needs_cpu
# define arch_needs_cpu(cpu) (0)
# endif
# else
static inline void tick_clock_notify(void) { }
static inline int tick_check_oneshot_change(int allow_nohz) { return 0; }

1
include/linux/time.h
View File

@ -148,6 +148,7 @@ extern void monotonic_to_bootbased(struct timespec *ts);
extern struct timespec timespec_trunc(struct timespec t, unsigned gran);
extern int timekeeping_valid_for_hres(void);
extern u64 timekeeping_max_deferment(void);
extern void update_wall_time(void);
extern void update_xtime_cache(u64 nsec);
extern void timekeeping_leap_insert(int leapsecond);

4
include/linux/timex.h
View File

@ -261,11 +261,7 @@ static inline int ntp_synced(void)
#define NTP_SCALE_SHIFT 32
#ifdef CONFIG_NO_HZ
#define NTP_INTERVAL_FREQ (2)
#else
#define NTP_INTERVAL_FREQ (HZ)
#endif
#define NTP_INTERVAL_LENGTH (NSEC_PER_SEC/NTP_INTERVAL_FREQ)
/* Returns how long ticks are at present, in ns / 2^NTP_SCALE_SHIFT. */

24
init/calibrate.c
View File

@ -123,23 +123,26 @@ void __cpuinit calibrate_delay(void)
{
unsigned long ticks, loopbit;
int lps_precision = LPS_PREC;
static bool printed;
if (preset_lpj) {
loops_per_jiffy = preset_lpj;
printk(KERN_INFO
"Calibrating delay loop (skipped) preset value.. ");
} else if ((smp_processor_id() == 0) && lpj_fine) {
if (!printed)
pr_info("Calibrating delay loop (skipped) "
"preset value.. ");
} else if ((!printed) && lpj_fine) {
loops_per_jiffy = lpj_fine;
printk(KERN_INFO
"Calibrating delay loop (skipped), "
pr_info("Calibrating delay loop (skipped), "
"value calculated using timer frequency.. ");
} else if ((loops_per_jiffy = calibrate_delay_direct()) != 0) {
printk(KERN_INFO
"Calibrating delay using timer specific routine.. ");
if (!printed)
pr_info("Calibrating delay using timer "
"specific routine.. ");
} else {
loops_per_jiffy = (1<<12);
printk(KERN_INFO "Calibrating delay loop... ");
if (!printed)
pr_info("Calibrating delay loop... ");
while ((loops_per_jiffy <<= 1) != 0) {
/* wait for "start of" clock tick */
ticks = jiffies;
@ -170,7 +173,10 @@ void __cpuinit calibrate_delay(void)
loops_per_jiffy &= ~loopbit;
}
}
printk(KERN_CONT "%lu.%02lu BogoMIPS (lpj=%lu)\n",
if (!printed)
pr_cont("%lu.%02lu BogoMIPS (lpj=%lu)\n",
loops_per_jiffy/(500000/HZ),
(loops_per_jiffy/(5000/HZ)) % 100, loops_per_jiffy);
printed = true;
}

5
kernel/cpu.c
View File

@ -392,10 +392,9 @@ int disable_nonboot_cpus(void)
if (cpu == first_cpu)
continue;
error = _cpu_down(cpu, 1);
if (!error) {
if (!error)
cpumask_set_cpu(cpu, frozen_cpus);
printk("CPU%d is down\n", cpu);
} else {
else {
printk(KERN_ERR "Error taking CPU%d down: %d\n",
cpu, error);
break;

3
kernel/hrtimer.c
View File

@ -1238,7 +1238,8 @@ hrtimer_interrupt_hanging(struct clock_event_device *dev,
force_clock_reprogram = 1;
dev->min_delta_ns = (unsigned long)try_time.tv64 * 3;
printk(KERN_WARNING "hrtimer: interrupt too slow, "
"forcing clock min delta to %lu ns\n", dev->min_delta_ns);
"forcing clock min delta to %llu ns\n",
(unsigned long long) dev->min_delta_ns);
}
/*
* High resolution timer interrupt

5
kernel/posix-cpu-timers.c
View File

@ -384,7 +384,8 @@ int posix_cpu_clock_get(const clockid_t which_clock, struct timespec *tp)
/*
* Validate the clockid_t for a new CPU-clock timer, and initialize the timer.
* This is called from sys_timer_create with the new timer already locked.
* This is called from sys_timer_create() and do_cpu_nanosleep() with the
* new timer already all-zeros initialized.
*/
int posix_cpu_timer_create(struct k_itimer *new_timer)
{
@ -396,8 +397,6 @@ int posix_cpu_timer_create(struct k_itimer *new_timer)
return -EINVAL;
INIT_LIST_HEAD(&new_timer->it.cpu.entry);
new_timer->it.cpu.incr.sched = 0;
new_timer->it.cpu.expires.sched = 0;
read_lock(&tasklist_lock);
if (CPUCLOCK_PERTHREAD(new_timer->it_clock)) {

1
kernel/time.c
View File

@ -136,7 +136,6 @@ static inline void warp_clock(void)
write_seqlock_irq(&xtime_lock);
wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
xtime.tv_sec += sys_tz.tz_minuteswest * 60;
update_xtime_cache(0);
write_sequnlock_irq(&xtime_lock);
clock_was_set();
}

13
kernel/time/clockevents.c
View File

@ -20,6 +20,8 @@
#include <linux/sysdev.h>
#include <linux/tick.h>
#include "tick-internal.h"
/* The registered clock event devices */
static LIST_HEAD(clockevent_devices);
static LIST_HEAD(clockevents_released);
@ -37,10 +39,9 @@ static DEFINE_SPINLOCK(clockevents_lock);
*
* Math helper, returns latch value converted to nanoseconds (bound checked)
*/
unsigned long clockevent_delta2ns(unsigned long latch,
struct clock_event_device *evt)
u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt)
{
u64 clc = ((u64) latch << evt->shift);
u64 clc = (u64) latch << evt->shift;
if (unlikely(!evt->mult)) {
evt->mult = 1;
@ -50,10 +51,10 @@ unsigned long clockevent_delta2ns(unsigned long latch,
do_div(clc, evt->mult);
if (clc < 1000)
clc = 1000;
if (clc > LONG_MAX)
clc = LONG_MAX;
if (clc > KTIME_MAX)
clc = KTIME_MAX;
return (unsigned long) clc;
return clc;
}
EXPORT_SYMBOL_GPL(clockevent_delta2ns);

97
kernel/time/clocksource.c
View File

@ -107,6 +107,59 @@ u64 timecounter_cyc2time(struct timecounter *tc,
}
EXPORT_SYMBOL_GPL(timecounter_cyc2time);
/**
* clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
* @mult: pointer to mult variable
* @shift: pointer to shift variable
* @from: frequency to convert from
* @to: frequency to convert to
* @minsec: guaranteed runtime conversion range in seconds
*
* The function evaluates the shift/mult pair for the scaled math
* operations of clocksources and clockevents.
*
* @to and @from are frequency values in HZ. For clock sources @to is
* NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock
* event @to is the counter frequency and @from is NSEC_PER_SEC.
*
* The @minsec conversion range argument controls the time frame in
* seconds which must be covered by the runtime conversion with the
* calculated mult and shift factors. This guarantees that no 64bit
* overflow happens when the input value of the conversion is
* multiplied with the calculated mult factor. Larger ranges may
* reduce the conversion accuracy by chosing smaller mult and shift
* factors.
*/
void
clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec)
{
u64 tmp;
u32 sft, sftacc= 32;
/*
* Calculate the shift factor which is limiting the conversion
* range:
*/
tmp = ((u64)minsec * from) >> 32;
while (tmp) {
tmp >>=1;
sftacc--;
}
/*
* Find the conversion shift/mult pair which has the best
* accuracy and fits the maxsec conversion range:
*/
for (sft = 32; sft > 0; sft--) {
tmp = (u64) to << sft;
do_div(tmp, from);
if ((tmp >> sftacc) == 0)
break;
}
*mult = tmp;
*shift = sft;
}
/*[Clocksource internal variables]---------
* curr_clocksource:
* currently selected clocksource.
@ -413,6 +466,47 @@ void clocksource_touch_watchdog(void)
clocksource_resume_watchdog();
}
/**
* clocksource_max_deferment - Returns max time the clocksource can be deferred
* @cs: Pointer to clocksource
*
*/
static u64 clocksource_max_deferment(struct clocksource *cs)
{
u64 max_nsecs, max_cycles;
/*
* Calculate the maximum number of cycles that we can pass to the
* cyc2ns function without overflowing a 64-bit signed result. The
* maximum number of cycles is equal to ULLONG_MAX/cs->mult which
* is equivalent to the below.
* max_cycles < (2^63)/cs->mult
* max_cycles < 2^(log2((2^63)/cs->mult))
* max_cycles < 2^(log2(2^63) - log2(cs->mult))
* max_cycles < 2^(63 - log2(cs->mult))
* max_cycles < 1 << (63 - log2(cs->mult))
* Please note that we add 1 to the result of the log2 to account for
* any rounding errors, ensure the above inequality is satisfied and
* no overflow will occur.
*/
max_cycles = 1ULL << (63 - (ilog2(cs->mult) + 1));
/*
* The actual maximum number of cycles we can defer the clocksource is
* determined by the minimum of max_cycles and cs->mask.
*/
max_cycles = min_t(u64, max_cycles, (u64) cs->mask);
max_nsecs = clocksource_cyc2ns(max_cycles, cs->mult, cs->shift);
/*
* To ensure that the clocksource does not wrap whilst we are idle,
* limit the time the clocksource can be deferred by 12.5%. Please
* note a margin of 12.5% is used because this can be computed with
* a shift, versus say 10% which would require division.
*/
return max_nsecs - (max_nsecs >> 5);
}
#ifdef CONFIG_GENERIC_TIME
/**
@ -511,6 +605,9 @@ static void clocksource_enqueue(struct clocksource *cs)
*/
int clocksource_register(struct clocksource *cs)
{
/* calculate max idle time permitted for this clocksource */
cs->max_idle_ns = clocksource_max_deferment(cs);
mutex_lock(&clocksource_mutex);
clocksource_enqueue(cs);
clocksource_select();

4
kernel/time/tick-oneshot.c
View File

@ -50,9 +50,9 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
dev->min_delta_ns += dev->min_delta_ns >> 1;
printk(KERN_WARNING
"CE: %s increasing min_delta_ns to %lu nsec\n",
"CE: %s increasing min_delta_ns to %llu nsec\n",
dev->name ? dev->name : "?",
dev->min_delta_ns << 1);
(unsigned long long) dev->min_delta_ns << 1);
i = 0;
}

141
kernel/time/tick-sched.c
View File

@ -134,18 +134,13 @@ __setup("nohz=", setup_tick_nohz);
* value. We do this unconditionally on any cpu, as we don't know whether the
* cpu, which has the update task assigned is in a long sleep.
*/
static void tick_nohz_update_jiffies(void)
static void tick_nohz_update_jiffies(ktime_t now)
{
int cpu = smp_processor_id();
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
unsigned long flags;
ktime_t now;
if (!ts->tick_stopped)
return;
cpumask_clear_cpu(cpu, nohz_cpu_mask);
now = ktime_get();
ts->idle_waketime = now;
local_irq_save(flags);
@ -155,20 +150,17 @@ static void tick_nohz_update_jiffies(void)
touch_softlockup_watchdog();
}
static void tick_nohz_stop_idle(int cpu)
static void tick_nohz_stop_idle(int cpu, ktime_t now)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
ktime_t delta;
if (ts->idle_active) {
ktime_t now, delta;
now = ktime_get();
delta = ktime_sub(now, ts->idle_entrytime);
ts->idle_lastupdate = now;
ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
ts->idle_active = 0;
delta = ktime_sub(now, ts->idle_entrytime);
ts->idle_lastupdate = now;
ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
ts->idle_active = 0;
sched_clock_idle_wakeup_event(0);
}
sched_clock_idle_wakeup_event(0);
}
static ktime_t tick_nohz_start_idle(struct tick_sched *ts)
@ -216,6 +208,7 @@ void tick_nohz_stop_sched_tick(int inidle)
struct tick_sched *ts;
ktime_t last_update, expires, now;
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
u64 time_delta;
int cpu;
local_irq_save(flags);
@ -263,7 +256,7 @@ void tick_nohz_stop_sched_tick(int inidle)
if (ratelimit < 10) {
printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
local_softirq_pending());
(unsigned int) local_softirq_pending());
ratelimit++;
}
goto end;
@ -275,14 +268,18 @@ void tick_nohz_stop_sched_tick(int inidle)
seq = read_seqbegin(&xtime_lock);
last_update = last_jiffies_update;
last_jiffies = jiffies;
time_delta = timekeeping_max_deferment();
} while (read_seqretry(&xtime_lock, seq));
/* Get the next timer wheel timer */
next_jiffies = get_next_timer_interrupt(last_jiffies);
delta_jiffies = next_jiffies - last_jiffies;
if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu))
if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
arch_needs_cpu(cpu)) {
next_jiffies = last_jiffies + 1;
delta_jiffies = 1;
} else {
/* Get the next timer wheel timer */
next_jiffies = get_next_timer_interrupt(last_jiffies);
delta_jiffies = next_jiffies - last_jiffies;
}
/*
* Do not stop the tick, if we are only one off
* or if the cpu is required for rcu
@ -293,23 +290,52 @@ void tick_nohz_stop_sched_tick(int inidle)
/* Schedule the tick, if we are at least one jiffie off */
if ((long)delta_jiffies >= 1) {
/*
* calculate the expiry time for the next timer wheel
* timer
*/
expires = ktime_add_ns(last_update, tick_period.tv64 *
delta_jiffies);
/*
* If this cpu is the one which updates jiffies, then
* give up the assignment and let it be taken by the
* cpu which runs the tick timer next, which might be
* this cpu as well. If we don't drop this here the
* jiffies might be stale and do_timer() never
* invoked.
* invoked. Keep track of the fact that it was the one
* which had the do_timer() duty last. If this cpu is
* the one which had the do_timer() duty last, we
* limit the sleep time to the timekeeping
* max_deferement value which we retrieved
* above. Otherwise we can sleep as long as we want.
*/
if (cpu == tick_do_timer_cpu)
if (cpu == tick_do_timer_cpu) {
tick_do_timer_cpu = TICK_DO_TIMER_NONE;
ts->do_timer_last = 1;
} else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
time_delta = KTIME_MAX;
ts->do_timer_last = 0;
} else if (!ts->do_timer_last) {
time_delta = KTIME_MAX;
}
/*
* calculate the expiry time for the next timer wheel
* timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
* that there is no timer pending or at least extremely
* far into the future (12 days for HZ=1000). In this
* case we set the expiry to the end of time.
*/
if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
/*
* Calculate the time delta for the next timer event.
* If the time delta exceeds the maximum time delta
* permitted by the current clocksource then adjust
* the time delta accordingly to ensure the
* clocksource does not wrap.
*/
time_delta = min_t(u64, time_delta,
tick_period.tv64 * delta_jiffies);
}
if (time_delta < KTIME_MAX)
expires = ktime_add_ns(last_update, time_delta);
else
expires.tv64 = KTIME_MAX;
if (delta_jiffies > 1)
cpumask_set_cpu(cpu, nohz_cpu_mask);
@ -342,22 +368,19 @@ void tick_nohz_stop_sched_tick(int inidle)
ts->idle_sleeps++;
/* Mark expires */
ts->idle_expires = expires;
/*
* delta_jiffies >= NEXT_TIMER_MAX_DELTA signals that
* there is no timer pending or at least extremly far
* into the future (12 days for HZ=1000). In this case
* we simply stop the tick timer:
* If the expiration time == KTIME_MAX, then
* in this case we simply stop the tick timer.
*/
if (unlikely(delta_jiffies >= NEXT_TIMER_MAX_DELTA)) {
ts->idle_expires.tv64 = KTIME_MAX;
if (unlikely(expires.tv64 == KTIME_MAX)) {
if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
hrtimer_cancel(&ts->sched_timer);
goto out;
}
/* Mark expiries */
ts->idle_expires = expires;
if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
hrtimer_start(&ts->sched_timer, expires,
HRTIMER_MODE_ABS_PINNED);
@ -436,7 +459,11 @@ void tick_nohz_restart_sched_tick(void)
ktime_t now;
local_irq_disable();
tick_nohz_stop_idle(cpu);
if (ts->idle_active || (ts->inidle && ts->tick_stopped))
now = ktime_get();
if (ts->idle_active)
tick_nohz_stop_idle(cpu, now);
if (!ts->inidle || !ts->tick_stopped) {
ts->inidle = 0;
@ -450,7 +477,6 @@ void tick_nohz_restart_sched_tick(void)
/* Update jiffies first */
select_nohz_load_balancer(0);
now = ktime_get();
tick_do_update_jiffies64(now);
cpumask_clear_cpu(cpu, nohz_cpu_mask);
@ -584,22 +610,18 @@ static void tick_nohz_switch_to_nohz(void)
* timer and do not touch the other magic bits which need to be done
* when idle is left.
*/
static void tick_nohz_kick_tick(int cpu)
static void tick_nohz_kick_tick(int cpu, ktime_t now)
{
#if 0
/* Switch back to 2.6.27 behaviour */
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
ktime_t delta, now;
if (!ts->tick_stopped)
return;
ktime_t delta;
/*
* Do not touch the tick device, when the next expiry is either
* already reached or less/equal than the tick period.
*/
now = ktime_get();
delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now);
if (delta.tv64 <= tick_period.tv64)
return;
@ -608,9 +630,26 @@ static void tick_nohz_kick_tick(int cpu)
#endif
}
static inline void tick_check_nohz(int cpu)
{
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
ktime_t now;
if (!ts->idle_active && !ts->tick_stopped)
return;
now = ktime_get();
if (ts->idle_active)
tick_nohz_stop_idle(cpu, now);
if (ts->tick_stopped) {
tick_nohz_update_jiffies(now);
tick_nohz_kick_tick(cpu, now);
}
}
#else
static inline void tick_nohz_switch_to_nohz(void) { }
static inline void tick_check_nohz(int cpu) { }
#endif /* NO_HZ */
@ -620,11 +659,7 @@ static inline void tick_nohz_switch_to_nohz(void) { }
void tick_check_idle(int cpu)
{
tick_check_oneshot_broadcast(cpu);
#ifdef CONFIG_NO_HZ
tick_nohz_stop_idle(cpu);
tick_nohz_update_jiffies();
tick_nohz_kick_tick(cpu);
#endif
tick_check_nohz(cpu);
}
/*

119
kernel/time/timekeeping.c
View File

@ -165,13 +165,6 @@ struct timespec raw_time;
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
static struct timespec xtime_cache __attribute__ ((aligned (16)));
void update_xtime_cache(u64 nsec)
{
xtime_cache = xtime;
timespec_add_ns(&xtime_cache, nsec);
}
/* must hold xtime_lock */
void timekeeping_leap_insert(int leapsecond)
{
@ -332,8 +325,6 @@ int do_settimeofday(struct timespec *tv)
xtime = *tv;
update_xtime_cache(0);
timekeeper.ntp_error = 0;
ntp_clear();
@ -487,6 +478,17 @@ int timekeeping_valid_for_hres(void)
return ret;
}
/**
* timekeeping_max_deferment - Returns max time the clocksource can be deferred
*
* Caller must observe xtime_lock via read_seqbegin/read_seqretry to
* ensure that the clocksource does not change!
*/
u64 timekeeping_max_deferment(void)
{
return timekeeper.clock->max_idle_ns;
}
/**
* read_persistent_clock - Return time from the persistent clock.
*
@ -548,7 +550,6 @@ void __init timekeeping_init(void)
}
set_normalized_timespec(&wall_to_monotonic,
-boot.tv_sec, -boot.tv_nsec);
update_xtime_cache(0);
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
@ -582,7 +583,6 @@ static int timekeeping_resume(struct sys_device *dev)
wall_to_monotonic = timespec_sub(wall_to_monotonic, ts);
total_sleep_time = timespec_add_safe(total_sleep_time, ts);
}
update_xtime_cache(0);
/* re-base the last cycle value */
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
timekeeper.ntp_error = 0;
@ -722,6 +722,49 @@ static void timekeeping_adjust(s64 offset)
timekeeper.ntp_error_shift;
}
/**
* logarithmic_accumulation - shifted accumulation of cycles
*
* This functions accumulates a shifted interval of cycles into
* into a shifted interval nanoseconds. Allows for O(log) accumulation
* loop.
*
* Returns the unconsumed cycles.
*/
static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
{
u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
/* If the offset is smaller then a shifted interval, do nothing */
if (offset < timekeeper.cycle_interval<<shift)
return offset;
/* Accumulate one shifted interval */
offset -= timekeeper.cycle_interval << shift;
timekeeper.clock->cycle_last += timekeeper.cycle_interval << shift;
timekeeper.xtime_nsec += timekeeper.xtime_interval << shift;
while (timekeeper.xtime_nsec >= nsecps) {
timekeeper.xtime_nsec -= nsecps;
xtime.tv_sec++;
second_overflow();
}
/* Accumulate into raw time */
raw_time.tv_nsec += timekeeper.raw_interval << shift;;
while (raw_time.tv_nsec >= NSEC_PER_SEC) {
raw_time.tv_nsec -= NSEC_PER_SEC;
raw_time.tv_sec++;
}
/* Accumulate error between NTP and clock interval */
timekeeper.ntp_error += tick_length << shift;
timekeeper.ntp_error -= timekeeper.xtime_interval <<
(timekeeper.ntp_error_shift + shift);
return offset;
}
/**
* update_wall_time - Uses the current clocksource to increment the wall time
*
@ -731,7 +774,7 @@ void update_wall_time(void)
{
struct clocksource *clock;
cycle_t offset;
u64 nsecs;
int shift = 0, maxshift;
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
@ -745,33 +788,22 @@ void update_wall_time(void)
#endif
timekeeper.xtime_nsec = (s64)xtime.tv_nsec << timekeeper.shift;
/* normally this loop will run just once, however in the
* case of lost or late ticks, it will accumulate correctly.
/*
* With NO_HZ we may have to accumulate many cycle_intervals
* (think "ticks") worth of time at once. To do this efficiently,
* we calculate the largest doubling multiple of cycle_intervals
* that is smaller then the offset. We then accumulate that
* chunk in one go, and then try to consume the next smaller
* doubled multiple.
*/
shift = ilog2(offset) - ilog2(timekeeper.cycle_interval);
shift = max(0, shift);
/* Bound shift to one less then what overflows tick_length */
maxshift = (8*sizeof(tick_length) - (ilog2(tick_length)+1)) - 1;
shift = min(shift, maxshift);
while (offset >= timekeeper.cycle_interval) {
u64 nsecps = (u64)NSEC_PER_SEC << timekeeper.shift;
/* accumulate one interval */
offset -= timekeeper.cycle_interval;
clock->cycle_last += timekeeper.cycle_interval;
timekeeper.xtime_nsec += timekeeper.xtime_interval;
if (timekeeper.xtime_nsec >= nsecps) {
timekeeper.xtime_nsec -= nsecps;
xtime.tv_sec++;
second_overflow();
}
raw_time.tv_nsec += timekeeper.raw_interval;
if (raw_time.tv_nsec >= NSEC_PER_SEC) {
raw_time.tv_nsec -= NSEC_PER_SEC;
raw_time.tv_sec++;
}
/* accumulate error between NTP and clock interval */
timekeeper.ntp_error += tick_length;
timekeeper.ntp_error -= timekeeper.xtime_interval <<
timekeeper.ntp_error_shift;
offset = logarithmic_accumulation(offset, shift);
shift--;
}
/* correct the clock when NTP error is too big */
@ -807,9 +839,6 @@ void update_wall_time(void)
timekeeper.ntp_error += timekeeper.xtime_nsec <<
timekeeper.ntp_error_shift;
nsecs = clocksource_cyc2ns(offset, timekeeper.mult, timekeeper.shift);
update_xtime_cache(nsecs);
/* check to see if there is a new clocksource to use */
update_vsyscall(&xtime, timekeeper.clock);
}
@ -846,13 +875,13 @@ void monotonic_to_bootbased(struct timespec *ts)
unsigned long get_seconds(void)
{
return xtime_cache.tv_sec;
return xtime.tv_sec;
}
EXPORT_SYMBOL(get_seconds);
struct timespec __current_kernel_time(void)
{
return xtime_cache;
return xtime;
}
struct timespec current_kernel_time(void)
@ -862,8 +891,7 @@ struct timespec current_kernel_time(void)
do {
seq = read_seqbegin(&xtime_lock);
now = xtime_cache;
now = xtime;
} while (read_seqretry(&xtime_lock, seq));
return now;
@ -877,8 +905,7 @@ struct timespec get_monotonic_coarse(void)
do {
seq = read_seqbegin(&xtime_lock);
now = xtime_cache;
now = xtime;
mono = wall_to_monotonic;
} while (read_seqretry(&xtime_lock, seq));

10
kernel/time/timer_list.c
View File

@ -204,10 +204,12 @@ print_tickdevice(struct seq_file *m, struct tick_device *td, int cpu)
return;
}
SEQ_printf(m, "%s\n", dev->name);
SEQ_printf(m, " max_delta_ns: %lu\n", dev->max_delta_ns);
SEQ_printf(m, " min_delta_ns: %lu\n", dev->min_delta_ns);
SEQ_printf(m, " mult: %lu\n", dev->mult);
SEQ_printf(m, " shift: %d\n", dev->shift);
SEQ_printf(m, " max_delta_ns: %llu\n",
(unsigned long long) dev->max_delta_ns);
SEQ_printf(m, " min_delta_ns: %llu\n",
(unsigned long long) dev->min_delta_ns);
SEQ_printf(m, " mult: %u\n", dev->mult);
SEQ_printf(m, " shift: %u\n", dev->shift);
SEQ_printf(m, " mode: %d\n", dev->mode);
SEQ_printf(m, " next_event: %Ld nsecs\n",
(unsigned long long) ktime_to_ns(dev->next_event));