The patch titled
dynticks: extend next_timer_interrupt() to use a reference jiffie
has been added to the -mm tree. Its filename is
dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: dynticks: extend next_timer_interrupt() to use a reference jiffie
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
For CONFIG_NO_HZ we need to calculate the next timer wheel event based
on a given jiffie value. Extend the existing code to allow the extra
'now' argument. Provide a compability function for the existing
implementations to call the function with now == jiffies. (This also
solves the racyness of the original code vs. jiffies changing during
the iteration.)
No functional changes to existing users of this infrastructure.
[ remove WARN_ON() that triggered on s390, by Carsten Otte <cotte@xxxxxxxxxx> ]
[ made new helper static, Adrian Bunk <bunk@xxxxxxxxx> ]
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
include/linux/timer.h | 10 ++++
kernel/timer.c | 97 +++++++++++++++++++++++++++++-----------
2 files changed, 81 insertions(+), 26 deletions(-)
diff -puN include/linux/timer.h~dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie include/linux/timer.h
--- a/include/linux/timer.h~dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie
+++ a/include/linux/timer.h
@@ -61,7 +61,17 @@ extern int del_timer(struct timer_list *
extern int __mod_timer(struct timer_list *timer, unsigned long expires);
extern int mod_timer(struct timer_list *timer, unsigned long expires);
+/*
+ * Return when the next timer-wheel timeout occurs (in absolute jiffies),
+ * locks the timer base:
+ */
extern unsigned long next_timer_interrupt(void);
+/*
+ * Return when the next timer-wheel timeout occurs (in absolute jiffies),
+ * locks the timer base and does the comparison against the given
+ * jiffie.
+ */
+extern unsigned long get_next_timer_interrupt(unsigned long now);
/***
* add_timer - start a timer
diff -puN kernel/timer.c~dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie kernel/timer.c
--- a/kernel/timer.c~dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie
+++ a/kernel/timer.c
@@ -597,29 +597,15 @@ static inline void __run_timers(tvec_bas
* is used on S/390 to stop all activity when a cpus is idle.
* This functions needs to be called disabled.
*/
-unsigned long next_timer_interrupt(void)
+static unsigned long __next_timer_interrupt(tvec_base_t *base,
+ unsigned long now)
{
- tvec_base_t *base;
struct list_head *list;
- struct timer_list *nte;
+ struct timer_list *nte, *found = NULL;
unsigned long expires;
- unsigned long hr_expires = MAX_JIFFY_OFFSET;
- ktime_t hr_delta;
tvec_t *varray[4];
int i, j;
- hr_delta = hrtimer_get_next_event();
- if (hr_delta.tv64 != KTIME_MAX) {
- struct timespec tsdelta;
- tsdelta = ktime_to_timespec(hr_delta);
- hr_expires = timespec_to_jiffies(&tsdelta);
- if (hr_expires < 3)
- return hr_expires + jiffies;
- }
- hr_expires += jiffies;
-
- base = __get_cpu_var(tvec_bases);
- spin_lock(&base->lock);
expires = base->timer_jiffies + (LONG_MAX >> 1);
list = NULL;
@@ -628,6 +614,7 @@ unsigned long next_timer_interrupt(void)
do {
list_for_each_entry(nte, base->tv1.vec + j, entry) {
expires = nte->expires;
+ found = nte;
if (j < (base->timer_jiffies & TVR_MASK))
list = base->tv2.vec + (INDEX(0));
goto found;
@@ -647,9 +634,12 @@ unsigned long next_timer_interrupt(void)
j = (j + 1) & TVN_MASK;
continue;
}
- list_for_each_entry(nte, varray[i]->vec + j, entry)
- if (time_before(nte->expires, expires))
+ list_for_each_entry(nte, varray[i]->vec + j, entry) {
+ if (time_before(nte->expires, expires)) {
expires = nte->expires;
+ found = nte;
+ }
+ }
if (j < (INDEX(i)) && i < 3)
list = varray[i + 1]->vec + (INDEX(i + 1));
goto found;
@@ -663,10 +653,58 @@ found:
* where we found the timer element.
*/
list_for_each_entry(nte, list, entry) {
- if (time_before(nte->expires, expires))
+ if (time_before(nte->expires, expires)) {
expires = nte->expires;
+ found = nte;
+ }
}
}
+
+ return expires;
+}
+
+#ifdef CONFIG_NO_HZ
+
+unsigned long get_next_timer_interrupt(unsigned long now)
+{
+ tvec_base_t *base = __get_cpu_var(tvec_bases);
+ unsigned long expires;
+
+ spin_lock(&base->lock);
+ expires = __next_timer_interrupt(base, now);
+ spin_unlock(&base->lock);
+
+ /*
+ * 'Timer wheel time' can lag behind 'jiffies time' due to
+ * delayed processing, so make sure we return a value that
+ * makes sense externally. base->timer_jiffies is unchanged,
+ * so it is safe to access it outside the lock.
+ */
+
+ return expires - (now - base->timer_jiffies);
+}
+
+#else
+
+unsigned long next_timer_interrupt(void)
+{
+ tvec_base_t *base = __get_cpu_var(tvec_bases);
+ unsigned long expires;
+ unsigned long now = jiffies;
+ unsigned long hr_expires = MAX_JIFFY_OFFSET;
+ ktime_t hr_delta = hrtimer_get_next_event();
+
+ if (hr_delta.tv64 != KTIME_MAX) {
+ struct timespec tsdelta;
+ tsdelta = ktime_to_timespec(hr_delta);
+ hr_expires = timespec_to_jiffies(&tsdelta);
+ if (hr_expires < 3)
+ return hr_expires + now;
+ }
+ hr_expires += now;
+
+ spin_lock(&base->lock);
+ expires = __next_timer_interrupt(base, now);
spin_unlock(&base->lock);
/*
@@ -682,16 +720,23 @@ found:
* would falsely evaluate to true. If that is the case, just
* return jiffies so that we can immediately fire the local timer
*/
- if (time_before(expires, jiffies))
- return jiffies;
+ if (time_before(expires, now))
+ expires = now;
+ else if (time_before(hr_expires, expires))
+ expires = hr_expires;
- if (time_before(hr_expires, expires))
- return hr_expires;
-
- return expires;
+ /*
+ * 'Timer wheel time' can lag behind 'jiffies time' due to
+ * delayed processing, so make sure we return a value that
+ * makes sense externally. base->timer_jiffies is unchanged,
+ * so it is safe to access it outside the lock.
+ */
+ return expires - (now - base->timer_jiffies);
}
#endif
+#endif
+
/******************************************************************/
/*
_
Patches currently in -mm which might be from tglx@xxxxxxxxxxxxx are
origin.patch
git-mtd.patch
gtod-uninline-jiffiesh.patch
gtod-fix-multiple-conversion-bugs-in-msecs_to_jiffies.patch
gtod-fix-timeout-overflow.patch
gtod-persistent-clock-support-core.patch
gtod-persistent-clock-support-i386.patch
dynticks-uninline-irq_enter.patch
dynticks-extend-next_timer_interrupt-to-use-a-reference-jiffie.patch
hrtimers-namespace-and-enum-cleanup.patch
hrtimers-clean-up-locking.patch
hrtimers-add-state-tracking.patch
hrtimers-clean-up-callback-tracking.patch
hrtimers-move-and-add-documentation.patch
acpi-include-fix.patch
acpi-keep-track-of-timer-broadcast.patch
acpi-add-state-propagation-for-dynamic-broadcasting.patch
acpi-cleanups-allow-early-access-to-pmtimer.patch
i386-apic-clean-up-the-apic-code.patch
clockevents-core.patch
clockevents-i386-drivers.patch
clockevents-i386-hpet-driver.patch
i386-apic-rework-and-fix-local-apic-calibration.patch
high-res-timers-core.patch
high-res-timers-core-do-itimer-rearming-in-process-context.patch
high-res-timers-allow-tsc-clocksource-if-pmtimer-present.patch
dynticks-core.patch
dynticks-add-nohz-stats-to-proc-stat.patch
dynticks-i386-support-idle-handler-callbacks.patch
dynticks-i386-prepare-nmi-watchdog.patch
high-res-timers-dynticks-i386-support-enable-in-kconfig.patch
debugging-feature-add-proc-timer_stat.patch
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