[RFC][UPDATE PATCH 2/4] convert soft-timer subsystem to timerintervals

Nishanth Aravamudan
2005-05-18T08:24:16Z

On 17.05.2005 [16:36:16 -0700], Nishanth Aravamudan wrote:
> On 17.05.2005 [16:33:00 -0700], Nishanth Aravamudan wrote:
> > On 13.05.2005 [17:16:35 -0700], john stultz wrote:
> > > All,
> > > This patch implements the architecture independent portion of the new
> > > time of day subsystem. For a brief description on the rework, see here:
> > > http://lwn.net/Articles/120850/ (Many thanks to the LWN team for that
> > > easy to understand writeup!)
> > >
> > > I intend this to be the last RFC release and to submit this patch to
> > > Andrew for for testing near the end of this month. So please, if you
> > > have any complaints, suggestions, or blocking issues, let me know.
> >
> > I have been working closely with John to re-work the soft-timer subsytem
> > to use the new timeofday() subsystem. The following patches attempts to
> > begin this process. I would greatly appreciate any comments.
>
> Description: Rework the soft-timer subsytem to use timerintervals (a new
> unit) instead of jiffies for expiration and addition. timerintervals are
> nothing more than the nanosecond time returned by the new
> timeofday-subsystem shifted down a certain number of bits (thus
> determining the precisino of the soft-timer subsystem at compile-time).

Sorry, this patch introduced a bug in the nsecs->timerinterval
conversion functions which prevented the kernel from booting. Please use
the following patch instead.

Thanks,
Nish

Description: Rework the soft-timer subsytem to use timerintervals (a new
unit) instead of jiffies for expiration and addition. timerintervals are
nothing more than the nanosecond time returned by the new
timeofday-subsystem shifted down a certain number of bits (thus
determining the precisino of the soft-timer subsystem at compile-time).

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>

diff -urpN 2.6.12-rc4-tod/include/linux/jiffies.h 2.6.12-rc4-tod-timer/include/linux/jiffies.h
--- 2.6.12-rc4-tod/include/linux/jiffies.h 2005-05-06 22:20:31.000000000 -0700
+++ 2.6.12-rc4-tod-timer/include/linux/jiffies.h 2005-05-18 00:29:42.000000000 -0700
@@ -263,7 +263,7 @@ static inline unsigned int jiffies_to_ms
#endif
}

-static inline unsigned int jiffies_to_usecs(const unsigned long j)
+static inline unsigned long jiffies_to_usecs(const unsigned long j)
{
#if HZ <= 1000000 && !(1000000 % HZ)
return (1000000 / HZ) * j;
@@ -274,6 +274,17 @@ static inline unsigned int jiffies_to_us
#endif
}

+static inline nsec_t jiffies_to_nsecs(const unsigned long j)
+{
+#if HZ <= NSEC_PER_SEC && !(NSEC_PER_SEC % HZ)
+ return (NSEC_PER_SEC / HZ) * (nsec_t)j;
+#elif HZ > NSEC_PER_SEC && !(HZ % NSEC_PER_SEC)
+ return ((nsec_t)j + (HZ / NSEC_PER_SEC) - 1)/(HZ / NSEC_PER_SEC);
+#else
+ return ((nsec_t)j * NSEC_PER_SEC) / HZ;
+#endif
+}
+
static inline unsigned long msecs_to_jiffies(const unsigned int m)
{
if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
@@ -287,7 +298,7 @@ static inline unsigned long msecs_to_jif
#endif
}

-static inline unsigned long usecs_to_jiffies(const unsigned int u)
+static inline unsigned long usecs_to_jiffies(const unsigned long u)
{
if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
return MAX_JIFFY_OFFSET;
@@ -300,6 +311,24 @@ static inline unsigned long usecs_to_jif
#endif
}

+static inline unsigned long nsecs_to_jiffies(const nsec_t n)
+{
+ nsec_t temp;
+ if (n > jiffies_to_nsecs(MAX_JIFFY_OFFSET))
+ return MAX_JIFFY_OFFSET;
+#if HZ <= NSEC_PER_SEC && !(NSEC_PER_SEC % HZ)
+ temp = n + (NSEC_PER_SEC / HZ) - 1;
+ do_div(temp, (NSEC_PER_SEC / HZ));
+ return (unsigned long)temp;
+#elif HZ > NSEC_PER_SEC && !(HZ % NSEC_PER_SEC)
+ return n * (HZ / NSEC_PER_SEC);
+#else
+ temp = n * HZ + NSEC_PER_SEC - 1;
+ do_div(temp, NSEC_PER_SEC);
+ return (unsigned long)temp;
+#endif
+}
+
/*
* The TICK_NSEC - 1 rounds up the value to the next resolution. Note
* that a remainder subtract here would not do the right thing as the
diff -urpN 2.6.12-rc4-tod/include/linux/sched.h 2.6.12-rc4-tod-timer/include/linux/sched.h
--- 2.6.12-rc4-tod/include/linux/sched.h 2005-05-06 22:20:31.000000000 -0700
+++ 2.6.12-rc4-tod-timer/include/linux/sched.h 2005-05-18 00:29:42.000000000 -0700
@@ -182,7 +182,13 @@ extern void scheduler_tick(void);
extern int in_sched_functions(unsigned long addr);

#define MAX_SCHEDULE_TIMEOUT LONG_MAX
+#define MAX_SCHEDULE_TIMEOUT_NSECS ((nsec_t)(-1))
+#define MAX_SCHEDULE_TIMEOUT_USECS ULONG_MAX
+#define MAX_SCHEDULE_TIMEOUT_MSECS UINT_MAX
extern signed long FASTCALL(schedule_timeout(signed long timeout));
+extern nsec_t FASTCALL(schedule_timeout_nsecs(nsec_t timeout_nsecs));
+extern unsigned long FASTCALL(schedule_timeout_usecs(unsigned long timeout_usecs));
+extern unsigned int FASTCALL(schedule_timeout_msecs(unsigned int timeout_msesc));
asmlinkage void schedule(void);

struct namespace;
diff -urpN 2.6.12-rc4-tod/include/linux/time.h 2.6.12-rc4-tod-timer/include/linux/time.h
--- 2.6.12-rc4-tod/include/linux/time.h 2005-05-17 23:35:49.000000000 -0700
+++ 2.6.12-rc4-tod-timer/include/linux/time.h 2005-05-18 00:29:42.000000000 -0700
@@ -40,6 +40,10 @@ typedef u64 cycle_t;
#define NSEC_PER_SEC (1000000000L)
#endif

+#ifndef NSEC_PER_MSEC
+#define NSEC_PER_MSEC (1000000L)
+#endif
+
#ifndef NSEC_PER_USEC
#define NSEC_PER_USEC (1000L)
#endif
diff -urpN 2.6.12-rc4-tod/include/linux/timer.h 2.6.12-rc4-tod-timer/include/linux/timer.h
--- 2.6.12-rc4-tod/include/linux/timer.h 2005-05-06 22:20:31.000000000 -0700
+++ 2.6.12-rc4-tod-timer/include/linux/timer.h 2005-05-18 00:29:42.000000000 -0700
@@ -5,6 +5,7 @@
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
+#include <linux/timeofday.h>

struct tvec_t_base_s;

@@ -65,27 +66,13 @@ extern void add_timer_on(struct timer_li
extern int del_timer(struct timer_list * timer);
extern int __mod_timer(struct timer_list *timer, unsigned long expires);
extern int mod_timer(struct timer_list *timer, unsigned long expires);
+extern void add_timer(struct timer_list *timer);
+extern int set_timer_nsecs(struct timer_list *timer, nsec_t expires_nsecs);
+extern void set_timer_on_nsecs(struct timer_list *timer, nsec_t expires_nsecs,
+ int cpu);

extern unsigned long next_timer_interrupt(void);

-/***
- * add_timer - start a timer
- * @timer: the timer to be added
- *
- * The kernel will do a ->function(->data) callback from the
- * timer interrupt at the ->expired point in the future. The
- * current time is 'jiffies'.
- *
- * The timer's ->expired, ->function (and if the handler uses it, ->data)
- * fields must be set prior calling this function.
- *
- * Timers with an ->expired field in the past will be executed in the next
- * timer tick.
- */
-static inline void add_timer(struct timer_list * timer)
-{
- __mod_timer(timer, timer->expires);
-}

#ifdef CONFIG_SMP
extern int del_timer_sync(struct timer_list *timer);
diff -urpN 2.6.12-rc4-tod/kernel/timer.c 2.6.12-rc4-tod-timer/kernel/timer.c
--- 2.6.12-rc4-tod/kernel/timer.c 2005-05-17 23:35:49.000000000 -0700
+++ 2.6.12-rc4-tod-timer/kernel/timer.c 2005-05-18 01:08:59.000000000 -0700
@@ -33,6 +33,7 @@
#include <linux/posix-timers.h>
#include <linux/cpu.h>
#include <linux/syscalls.h>
+#include <linux/timeofday.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>
@@ -56,6 +57,15 @@ static void time_interpolator_update(lon
#define TVR_SIZE (1 << TVR_BITS)
#define TVN_MASK (TVN_SIZE - 1)
#define TVR_MASK (TVR_SIZE - 1)
+/*
+ * Modifying TIMERINTERVAL_BITS changes the software resolution of
+ * soft-timers. While 20 bits would be closer to a millisecond, there
+ * are performance gains from allowing a software resolution finer than
+ * the hardware (HZ=1000)
+ */
+#define TIMERINTERVAL_BITS 19
+#define TIMERINTERVAL_SIZE (1 << TIMERINTERVAL_BITS)
+#define TIMERINTERVAL_MASK (TIMERINTERVAL_SIZE - 1)

typedef struct tvec_s {
struct list_head vec[TVN_SIZE];
@@ -67,7 +77,7 @@ typedef struct tvec_root_s {

struct tvec_t_base_s {
spinlock_t lock;
- unsigned long timer_jiffies;
+ unsigned long last_timer_time;
struct timer_list *running_timer;
tvec_root_t tv1;
tvec_t tv2;
@@ -113,11 +123,89 @@ static inline void check_timer(struct ti
check_timer_failed(timer);
}

+/*
+ * nsecs_to_timerintervals_ceiling - convert nanoseconds to timerintervals
+ * @n: number of nanoseconds to convert
+ *
+ * This is where changes to TIMERINTERVAL_BITS affect the soft-timer
+ * subsystem.
+ *
+ * Some explanation of the math is necessary:
+ * Rather than do decimal arithmetic, we shift for the sake of speed.
+ * This does mean that the actual requestable sleeps are
+ * 2^(sizeof(unsigned long)*8 - TIMERINTERVAL_BITS)
+ * timerintervals.
+ *
+ * The conditional takes care of the corner case where we request a 0
+ * nanosecond sleep; if the quantity were unsigned, we would not
+ * propogate the carry and force a wrap when adding the 1.
+ *
+ * To prevent timers from being expired early, we:
+ * Take the ceiling when we add; and
+ * Take the floor when we expire.
+ */
+static inline unsigned long nsecs_to_timerintervals_ceiling(nsec_t nsecs)
+{
+ if (nsecs)
+ return (unsigned long)(((nsecs - 1) >> TIMERINTERVAL_BITS) + 1);
+ else
+ return 0UL;
+}
+
+/*
+ * nsecs_to_timerintervals_floor - convert nanoseconds to timerintervals
+ * @n: number of nanoseconds to convert
+ *
+ * This is where changes to TIMERINTERVAL_BITS affect the soft-timer
+ * subsystem.
+ *
+ * Some explanation of the math is necessary:
+ * Rather than do decimal arithmetic, we shift for the sake of speed.
+ * This does mean that the actual requestable sleeps are
+ * 2^(sizeof(unsigned long)*8 - TIMERINTERVAL_BITS)
+ *
+ * There is no special case for 0 in the floor function, since we do not
+ * do any subtraction or addition of 1
+ *
+ * To prevent timers from being expired early, we:
+ * Take the ceiling when we add; and
+ * Take the floor when we expire.
+ */
+static inline unsigned long nsecs_to_timerintervals_floor(nsec_t nsecs)
+{
+ return (unsigned long)(nsecs >> TIMERINTERVAL_BITS);
+}
+
+/*
+ * jiffies_to_timerintervals - convert absolute jiffies to timerintervals
+ * @abs_jiffies: number of jiffies to convert
+ *
+ * First, we convert the absolute jiffies parameter to a relative
+ * jiffies value. To maintain precision, we convert the relative
+ * jiffies value to a relative nanosecond value and then convert that
+ * to a relative soft-timer interval unit value. We then add this
+ * relative value to the current time according to the timeofday-
+ * subsystem, converted to soft-timer interval units.
+ *
+ * We only use this function when adding timers, so we are free to
+ * always use the ceiling version of nsecs_to_timerintervals.
+ *
+ * This function only exists to support deprecated interfaces. Once
+ * those interfaces have been converted to the alternatives, it should
+ * be removed.
+ */
+static inline unsigned long jiffies_to_timerintervals(unsigned long abs_jiffies)
+{
+ unsigned long relative_jiffies = abs_jiffies - jiffies;
+ return nsecs_to_timerintervals_ceiling(do_monotonic_clock()) +
+ nsecs_to_timerintervals_ceiling(jiffies_to_nsecs(relative_jiffies));
+}

static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
{
+ /* expires is in timerintervals */
unsigned long expires = timer->expires;
- unsigned long idx = expires - base->timer_jiffies;
+ unsigned long idx = expires - base->last_timer_time;
struct list_head *vec;

if (idx < TVR_SIZE) {
@@ -137,7 +225,7 @@ static void internal_add_timer(tvec_base
* Can happen if you add a timer with expires == jiffies,
* or you set a timer to go off in the past
*/
- vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
+ vec = base->tv1.vec + (base->last_timer_time & TVR_MASK);
} else {
int i;
/* If the timeout is larger than 0xffffffff on 64-bit
@@ -145,7 +233,7 @@ static void internal_add_timer(tvec_base
*/
if (idx > 0xffffffffUL) {
idx = 0xffffffffUL;
- expires = idx + base->timer_jiffies;
+ expires = idx + base->last_timer_time;
}
i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
vec = base->tv5.vec + i;
@@ -207,6 +295,7 @@ repeat:
list_del(&timer->entry);
ret = 1;
}
+ /* expires is in timerintervals */
timer->expires = expires;
internal_add_timer(new_base, timer);
timer->base = new_base;
@@ -238,15 +327,41 @@ void add_timer_on(struct timer_list *tim
check_timer(timer);

spin_lock_irqsave(&base->lock, flags);
+ timer->expires = jiffies_to_timerintervals(timer->expires);
internal_add_timer(base, timer);
timer->base = base;
spin_unlock_irqrestore(&base->lock, flags);
}

+/***
+ * add_timer - start a timer
+ * @timer: the timer to be added
+ *
+ * The kernel will do a ->function(->data) callback from the
+ * timer interrupt at the ->expired point in the future. The
+ * current time is 'jiffies'.
+ *
+ * The timer's ->expired, ->function (and if the handler uses it, ->data)
+ * fields must be set prior calling this function.
+ *
+ * Timers with an ->expired field in the past will be executed in the next
+ * timer tick.
+ *
+ * The callers of add_timer() should be aware that the interface is now
+ * deprecated. set_timer_nsecs() is the single interface for adding and
+ * modifying timers.
+ */
+void add_timer(struct timer_list * timer)
+{
+ __mod_timer(timer, jiffies_to_timerintervals(timer->expires));
+}
+
+EXPORT_SYMBOL(add_timer);

/***
* mod_timer - modify a timer's timeout
* @timer: the timer to be modified
+ * @expires: absolute time, in jiffies, when timer should expire
*
* mod_timer is a more efficient way to update the expire field of an
* active timer (if the timer is inactive it will be activated)
@@ -262,6 +377,10 @@ void add_timer_on(struct timer_list *tim
* The function returns whether it has modified a pending timer or not.
* (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
* active timer returns 1.)
+ *
+ * The callers of mod_timer() should be aware that the interface is now
+ * deprecated. set_timer_nsecs() is the single interface for adding and
+ * modifying timers.
*/
int mod_timer(struct timer_list *timer, unsigned long expires)
{
@@ -269,6 +388,7 @@ int mod_timer(struct timer_list *timer,

check_timer(timer);

+ expires = jiffies_to_timerintervals(expires);
/*
* This is a common optimization triggered by the
* networking code - if the timer is re-modified
@@ -282,6 +402,59 @@ int mod_timer(struct timer_list *timer,

EXPORT_SYMBOL(mod_timer);

+/*
+ * set_timer_nsecs - modify a timer's timeout in nsecs
+ * @timer: the timer to be modified
+ *
+ * set_timer_nsecs replaces both add_timer and mod_timer. The caller
+ * should call do_monotonic_clock() to determine the absolute timeout
+ * necessary.
+ */
+int set_timer_nsecs(struct timer_list *timer, nsec_t expires_nsecs)
+{
+ unsigned long expires;
+
+ BUG_ON(!timer->function);
+
+ check_timer(timer);
+
+ /* make sure to round up */
+ expires = nsecs_to_timerintervals_ceiling(expires_nsecs);
+ if (timer_pending(timer) && timer->expires == expires)
+ return 1;
+
+ return __mod_timer(timer, expires);
+}
+
+EXPORT_SYMBOL_GPL(set_timer_nsecs);
+
+/***
+ * set_timer_on_nsecs - start a timer on a particular CPU
+ * @timer: the timer to be added
+ * @expires_nsecs: absolute time in nsecs when timer should expire
+ * @cpu: the CPU to start it on
+ *
+ * This is not very scalable on SMP. Double adds are not possible.
+ */
+void set_timer_on_nsecs(struct timer_list *timer, nsec_t expires_nsecs, int cpu)
+{
+ tvec_base_t *base = &per_cpu(tvec_bases, cpu);
+ unsigned long flags;
+
+ BUG_ON(timer_pending(timer) || !timer->function);
+
+ check_timer(timer);
+
+ spin_lock_irqsave(&base->lock, flags);
+ /* make sure to round up */
+ timer->expires = nsecs_to_timerintervals_ceiling(expires_nsecs);
+ internal_add_timer(base, timer);
+ timer->base = base;
+ spin_unlock_irqrestore(&base->lock, flags);
+}
+
+EXPORT_SYMBOL_GPL(set_timer_on_nsecs);
+
/***
* del_timer - deactive a timer.
* @timer: the timer to be deactivated
@@ -427,21 +600,22 @@ static int cascade(tvec_base_t *base, tv
/***
* __run_timers - run all expired timers (if any) on this CPU.
* @base: the timer vector to be processed.
+ * @current_timer_time: the current time in soft-timer interval units
*
* This function cascades all vectors and executes all expired timer
* vectors.
*/
-#define INDEX(N) (base->timer_jiffies >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK
+#define INDEX(N) (base->last_timer_time >> (TVR_BITS + N * TVN_BITS)) & TVN_MASK

-static inline void __run_timers(tvec_base_t *base)
+static inline void __run_timers(tvec_base_t *base, unsigned long current_timer_time)
{
struct timer_list *timer;

spin_lock_irq(&base->lock);
- while (time_after_eq(jiffies, base->timer_jiffies)) {
+ while (time_after_eq(current_timer_time, base->last_timer_time)) {
struct list_head work_list = LIST_HEAD_INIT(work_list);
struct list_head *head = &work_list;
- int index = base->timer_jiffies & TVR_MASK;
+ int index = base->last_timer_time & TVR_MASK;

/*
* Cascade timers:
@@ -451,7 +625,7 @@ static inline void __run_timers(tvec_bas
(!cascade(base, &base->tv3, INDEX(1))) &&
!cascade(base, &base->tv4, INDEX(2)))
cascade(base, &base->tv5, INDEX(3));
- ++base->timer_jiffies;
+ ++base->last_timer_time;
list_splice_init(base->tv1.vec + index, &work_list);
repeat:
if (!list_empty(head)) {
@@ -500,20 +674,20 @@ unsigned long next_timer_interrupt(void)

base = &__get_cpu_var(tvec_bases);
spin_lock(&base->lock);
- expires = base->timer_jiffies + (LONG_MAX >> 1);
+ expires = base->last_timer_time + (LONG_MAX >> 1);
list = 0;

/* Look for timer events in tv1. */
- j = base->timer_jiffies & TVR_MASK;
+ j = base->last_timer_time & TVR_MASK;
do {
list_for_each_entry(nte, base->tv1.vec + j, entry) {
expires = nte->expires;
- if (j < (base->timer_jiffies & TVR_MASK))
+ if (j < (base->last_timer_time & TVR_MASK))
list = base->tv2.vec + (INDEX(0));
goto found;
}
j = (j + 1) & TVR_MASK;
- } while (j != (base->timer_jiffies & TVR_MASK));
+ } while (j != (base->last_timer_time & TVR_MASK));

/* Check tv2-tv5. */
varray[0] = &base->tv2;
@@ -890,10 +1064,15 @@ EXPORT_SYMBOL(xtime_lock);
*/
static void run_timer_softirq(struct softirq_action *h)
{
+ unsigned long current_timer_time;
tvec_base_t *base = &__get_cpu_var(tvec_bases);

- if (time_after_eq(jiffies, base->timer_jiffies))
- __run_timers(base);
+ /* cache the converted current time, rounding down */
+ current_timer_time =
+ nsecs_to_timerintervals_floor(do_monotonic_clock());
+
+ if (time_after_eq(current_timer_time, base->last_timer_time))
+ __run_timers(base, current_timer_time);
}

/*
@@ -1078,6 +1257,10 @@ static void process_timeout(unsigned lon
* value will be %MAX_SCHEDULE_TIMEOUT.
*
* In all cases the return value is guaranteed to be non-negative.
+ *
+ * The callers of schedule_timeout() should be aware that the interface
+ * is now deprecated. schedule_timeout_{msecs,usecs,nsecs}() are now the
+ * interfaces for relative timeout requests.
*/
fastcall signed long __sched schedule_timeout(signed long timeout)
{
@@ -1133,6 +1316,149 @@ fastcall signed long __sched schedule_ti

EXPORT_SYMBOL(schedule_timeout);

+/**
+ * schedule_timeout_nsecs - sleep until timeout
+ * @timeout_nsecs: timeout value in nanoseconds
+ *
+ * Make the current task sleep until @timeout_nsecs nsecs have
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout_nsecs nsecs are guaranteed
+ * to pass before the routine returns. The routine will return 0
+ *
+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
+ * delivered to the current task. In this case the remaining time
+ * in nsecs will be returned, or 0 if the timer expired in time
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ *
+ * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT_NSECS will
+ * schedule the CPU away without a bound on the timeout. In this case
+ * the return value will be %MAX_SCHEDULE_TIMEOUT_NSECS.
+ */
+fastcall nsec_t __sched schedule_timeout_nsecs(nsec_t timeout_nsecs)
+{
+ struct timer_list timer;
+ nsec_t expires;
+
+ if (timeout_nsecs == MAX_SCHEDULE_TIMEOUT_NSECS) {
+ schedule();
+ goto out;
+ }
+
+ expires = do_monotonic_clock() + timeout_nsecs;
+
+ init_timer(&timer);
+ timer.data = (unsigned long) current;
+ timer.function = process_timeout;
+
+ set_timer_nsecs(&timer, expires);
+ schedule();
+ del_singleshot_timer_sync(&timer);
+
+ timeout_nsecs = do_monotonic_clock();
+ if (expires < timeout_nsecs)
+ timeout_nsecs = (nsec_t)0UL;
+ else
+ timeout_nsecs = expires - timeout_nsecs;
+out:
+ return timeout_nsecs;
+}
+
+EXPORT_SYMBOL_GPL(schedule_timeout_nsecs);
+
+/**
+ * schedule_timeout_usecs - sleep until timeout
+ * @timeout_usecs: timeout value in nanoseconds
+ *
+ * Make the current task sleep until @timeout_usecs usecs have
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout_usecs usecs are guaranteed
+ * to pass before the routine returns. The routine will return 0
+ *
+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
+ * delivered to the current task. In this case the remaining time
+ * in usecs will be returned, or 0 if the timer expired in time
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ *
+ * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT_USECS will
+ * schedule the CPU away without a bound on the timeout. In this case
+ * the return value will be %MAX_SCHEDULE_TIMEOUT_USECS.
+ */
+fastcall inline unsigned long __sched schedule_timeout_usecs(unsigned long timeout_usecs)
+{
+ nsec_t timeout_nsecs;
+
+ if (timeout_usecs == MAX_SCHEDULE_TIMEOUT_USECS)
+ timeout_nsecs = MAX_SCHEDULE_TIMEOUT_NSECS;
+ else
+ timeout_nsecs = timeout_usecs * (nsec_t)NSEC_PER_USEC;
+ /*
+ * Make sure to round up by subtracting one before division and
+ * adding one after
+ */
+ timeout_nsecs = schedule_timeout_nsecs(timeout_nsecs) - 1;
+ do_div(timeout_nsecs, NSEC_PER_USEC);
+ timeout_usecs = (unsigned long)timeout_nsecs + 1UL;
+ return timeout_usecs;
+}
+
+EXPORT_SYMBOL_GPL(schedule_timeout_usecs);
+
+/**
+ * schedule_timeout_msecs - sleep until timeout
+ * @timeout_msecs: timeout value in nanoseconds
+ *
+ * Make the current task sleep until @timeout_msecs msecs have
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout_msecs msecs are guaranteed
+ * to pass before the routine returns. The routine will return 0
+ *
+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
+ * delivered to the current task. In this case the remaining time
+ * in msecs will be returned, or 0 if the timer expired in time
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ *
+ * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT_MSECS will
+ * schedule the CPU away without a bound on the timeout. In this case
+ * the return value will be %MAX_SCHEDULE_TIMEOUT_MSECS.
+ */
+fastcall inline unsigned int __sched schedule_timeout_msecs(unsigned int timeout_msecs)
+{
+ nsec_t timeout_nsecs;
+
+ if (timeout_msecs == MAX_SCHEDULE_TIMEOUT_MSECS)
+ timeout_nsecs = MAX_SCHEDULE_TIMEOUT_NSECS;
+ else
+ timeout_nsecs = timeout_msecs * (nsec_t)NSEC_PER_MSEC;
+ /*
+ * Make sure to round up by subtracting one before division and
+ * adding one after
+ */
+ timeout_nsecs = schedule_timeout_nsecs(timeout_nsecs) - 1;
+ do_div(timeout_nsecs, NSEC_PER_MSEC);
+ timeout_msecs = (unsigned int)timeout_nsecs + 1;
+ return timeout_msecs;
+}
+
+EXPORT_SYMBOL_GPL(schedule_timeout_msecs);
+
/* Thread ID - the internal kernel "pid" */
asmlinkage long sys_gettid(void)
{
@@ -1302,7 +1628,11 @@ static void __devinit init_timers_cpu(in
for (j = 0; j < TVR_SIZE; j++)
INIT_LIST_HEAD(base->tv1.vec + j);

- base->timer_jiffies = jiffies;
+ /*
+ * Under the new montonic_clock() oriented soft-timer subsystem,
+ * we begin at 0, not INITIAL_JIFFIES
+ */
+ base->last_timer_time = 0UL;
}

#ifdef CONFIG_HOTPLUG_CPU