static u64 sched_clock_remote(struct sched_clock_data *scd)
{
struct sched_clock_data *my_scd = this_scd();
u64 this_clock, remote_clock;
u64 *ptr, old_val, val;
sched_clock_local(my_scd);
again:
this_clock = my_scd->clock;
remote_clock = scd->clock;
/*
* 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((s64)(remote_clock - this_clock) < 0)) {
ptr = &scd->clock;
old_val = remote_clock;
val = this_clock;
} else {
/*
* Should be rare, but possible:
*/
ptr = &my_scd->clock;
old_val = this_clock;
val = remote_clock;
}
if (cmpxchg64(ptr, old_val, val) != old_val)
goto again;
return val;
}
static u64 sched_clock_remote(struct sched_clock_data *scd)
{
struct sched_clock_data *my_scd = this_scd();
u64 this_clock, remote_clock;
u64 *ptr, old_val, val;
sched_clock_local(my_scd);
again:
this_clock = my_scd->clock;
remote_clock = scd->clock;
if (likely((s64)(remote_clock - this_clock) < 0)) {
ptr = &scd->clock;
old_val = remote_clock;
val = this_clock;
} else {
ptr = &my_scd->clock;
old_val = this_clock;
val = remote_clock;
}
if (cmpxchg64(ptr, old_val, val) != old_val)
goto again;
return val;
}
u64 sched_clock_cpu(int cpu)
{
u64 now, clock, this_clock, remote_clock;
struct sched_clock_data *scd;
if (sched_clock_stable)
return sched_clock();
scd = cpu_sdc(cpu);
/*
* Normally this is not called in NMI context - but if it is,
* trying to do any locking here is totally lethal.
*/
if (unlikely(in_nmi()))
return scd->clock;
if (unlikely(!sched_clock_running))
return 0ull;
WARN_ON_ONCE(!irqs_disabled());
now = sched_clock();
if (cpu != raw_smp_processor_id()) {
struct sched_clock_data *my_scd = this_scd();
lock_double_clock(scd, my_scd);
this_clock = __update_sched_clock(my_scd, now);
remote_clock = scd->clock;
/*
* 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((s64)(remote_clock - this_clock) < 0)) {
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);
} else {
__raw_spin_lock(&scd->lock);
clock = __update_sched_clock(scd, now);
}
__raw_spin_unlock(&scd->lock);
return clock;
}
static void __set_sched_clock_stable(void)
{
struct sched_clock_data *scd = this_scd();
/*
* Attempt to make the (initial) unstable->stable transition continuous.
*/
raw_offset = (scd->tick_gtod + gtod_offset) - (scd->tick_raw);
printk(KERN_INFO "sched_clock: Marking stable (%lld, %lld)->(%lld, %lld)\n",
scd->tick_gtod, gtod_offset,
scd->tick_raw, raw_offset);
static_branch_enable(&__sched_clock_stable);
tick_dep_clear(TICK_DEP_BIT_CLOCK_UNSTABLE);
}
/*
* 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();
}
u64 sched_clock_cpu(int cpu)
{
struct sched_clock_data *scd = cpu_sdc(cpu);
u64 now, clock;
if (unlikely(!sched_clock_running))
return 0ull;
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);
__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);
}
return clock;
}
void sched_clock_tick(void)
{
struct sched_clock_data *scd = this_scd();
u64 now, now_gtod;
if (unlikely(!sched_clock_running))
return;
WARN_ON_ONCE(!irqs_disabled());
now_gtod = ktime_to_ns(ktime_get());
now = sched_clock();
__raw_spin_lock(&scd->lock);
scd->tick_raw = now;
scd->tick_gtod = now_gtod;
__update_sched_clock(scd, now);
__raw_spin_unlock(&scd->lock);
}
void sched_clock_tick(void)
{
struct sched_clock_data *scd;
WARN_ON_ONCE(!irqs_disabled());
/*
* Update these values even if sched_clock_stable(), because it can
* become unstable at any point in time at which point we need some
* values to fall back on.
*
* XXX arguably we can skip this if we expose tsc_clocksource_reliable
*/
scd = this_scd();
scd->tick_raw = sched_clock();
scd->tick_gtod = ktime_get_ns();
if (!sched_clock_stable() && likely(sched_clock_running))
sched_clock_local(scd);
}
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))
return;
WARN_ON_ONCE(!irqs_disabled());
now_gtod = ktime_to_ns(ktime_get());
now = sched_clock();
__raw_spin_lock(&scd->lock);
__update_sched_clock(scd, now, NULL);
/*
* 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);
}
void sched_clock_tick(void)
{
struct sched_clock_data *scd;
u64 now, now_gtod;
if (sched_clock_stable)
return;
if (unlikely(!sched_clock_running))
return;
WARN_ON_ONCE(!irqs_disabled());
scd = this_scd();
now_gtod = ktime_to_ns(ktime_get());
now = sched_clock();
scd->tick_raw = now;
scd->tick_gtod = now_gtod;
sched_clock_local(scd);
}
static void __clear_sched_clock_stable(struct work_struct *work)
{
struct sched_clock_data *scd = this_scd();
/*
* Attempt to make the stable->unstable transition continuous.
*
* Trouble is, this is typically called from the TSC watchdog
* timer, which is late per definition. This means the tick
* values can already be screwy.
*
* Still do what we can.
*/
gtod_offset = (scd->tick_raw + raw_offset) - (scd->tick_gtod);
printk(KERN_INFO "sched_clock: Marking unstable (%lld, %lld)<-(%lld, %lld)\n",
scd->tick_gtod, gtod_offset,
scd->tick_raw, raw_offset);
static_branch_disable(&__sched_clock_stable);
tick_dep_set(TICK_DEP_BIT_CLOCK_UNSTABLE);
}
void sched_clock_tick(void)
{
struct sched_clock_data *scd = this_scd();
u64 now, now_gtod;
if (unlikely(!sched_clock_running))
return;
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);
}
static u64 sched_clock_remote(struct sched_clock_data *scd)
{
struct sched_clock_data *my_scd = this_scd();
u64 this_clock, remote_clock;
u64 *ptr, old_val, val;
#if BITS_PER_LONG != 64
again:
/*
* Careful here: The local and the remote clock values need to
* be read out atomic as we need to compare the values and
* then update either the local or the remote side. So the
* cmpxchg64 below only protects one readout.
*
* We must reread via sched_clock_local() in the retry case on
* 32bit as an NMI could use sched_clock_local() via the
* tracer and hit between the readout of
* the low32bit and the high 32bit portion.
*/
this_clock = sched_clock_local(my_scd);
/*
* We must enforce atomic readout on 32bit, otherwise the
* update on the remote cpu can hit inbetween the readout of
* the low32bit and the high 32bit portion.
*/
remote_clock = cmpxchg64(&scd->clock, 0, 0);
#else
/*
* On 64bit the read of [my]scd->clock is atomic versus the
* update, so we can avoid the above 32bit dance.
*/
sched_clock_local(my_scd);
again:
this_clock = my_scd->clock;
remote_clock = scd->clock;
#endif
/*
* 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((s64)(remote_clock - this_clock) < 0)) {
ptr = &scd->clock;
old_val = remote_clock;
val = this_clock;
} else {
/*
* Should be rare, but possible:
*/
ptr = &my_scd->clock;
old_val = this_clock;
val = remote_clock;
}
if (cmpxchg64(ptr, old_val, val) != old_val)
goto again;
return val;
}
