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Message-Id: <1170803853.3785.45.camel@chaos>
Date: Wed, 07 Feb 2007 00:17:33 +0100
From: Thomas Gleixner <tglx@...utronix.de>
To: Tilman Schmidt <tilman@...p.cc>
Cc: Ingo Molnar <mingo@...e.hu>, Andrew Morton <akpm@...l.org>,
linux-kernel@...r.kernel.org, mingo@...hat.com,
netdev@...r.kernel.org, netfilter-devel@...ts.netfilter.org
Subject: Re: dynticks + iptables almost stops the boot process [was: Re:
2.6.20-rc6-mm3]
On Wed, 2007-02-07 at 00:12 +0100, Tilman Schmidt wrote:
> > No, not this. Anyway the last patch Thomas forwarded does fix the
> > problem.
>
> Which one would that be? I might try it for comparison.
Find the combined patch of all fixlets on top of -mm3 below.
tglx
Index: linux-2.6.20/kernel/timer.c
===================================================================
--- linux-2.6.20.orig/kernel/timer.c
+++ linux-2.6.20/kernel/timer.c
@@ -985,8 +985,9 @@ static int timekeeping_resume(struct sys
if (now && (now > timekeeping_suspend_time)) {
unsigned long sleep_length = now - timekeeping_suspend_time;
+
xtime.tv_sec += sleep_length;
- jiffies_64 += (u64)sleep_length * HZ;
+ wall_to_monotonic.tv_sec -= sleep_length;
}
/* re-base the last cycle value */
clock->cycle_last = clocksource_read(clock);
@@ -994,7 +995,7 @@ static int timekeeping_resume(struct sys
timekeeping_suspended = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);
- clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
+ touch_softlockup_watchdog();
/* Resume hrtimers */
clock_was_set();
Index: linux-2.6.20/kernel/time/clockevents.c
===================================================================
--- linux-2.6.20.orig/kernel/time/clockevents.c
+++ linux-2.6.20/kernel/time/clockevents.c
@@ -42,8 +42,8 @@ unsigned long clockevent_delta2ns(unsign
u64 clc = ((u64) latch << evt->shift);
do_div(clc, evt->mult);
- if (clc < KTIME_MONOTONIC_RES.tv64)
- clc = KTIME_MONOTONIC_RES.tv64;
+ if (clc < 1000)
+ clc = 1000;
if (clc > LONG_MAX)
clc = LONG_MAX;
@@ -72,18 +72,22 @@ void clockevents_set_mode(struct clock_e
*
* Returns 0 on success, -ETIME when the event is in the past.
*/
-int clockevents_program_event(struct clock_event_device *dev, ktime_t expires)
+int clockevents_program_event(struct clock_event_device *dev, ktime_t expires,
+ ktime_t now)
{
unsigned long long clc;
int64_t delta;
- delta = ktime_to_ns(ktime_sub(expires, ktime_get()));
+ delta = ktime_to_ns(ktime_sub(expires, now));
if (delta <= 0)
return -ETIME;
dev->next_event = expires;
+ if (dev->mode == CLOCK_EVT_MODE_SHUTDOWN)
+ return 0;
+
if (delta > dev->max_delta_ns)
delta = dev->max_delta_ns;
if (delta < dev->min_delta_ns)
Index: linux-2.6.20/kernel/time/tick-broadcast.c
===================================================================
--- linux-2.6.20.orig/kernel/time/tick-broadcast.c
+++ linux-2.6.20/kernel/time/tick-broadcast.c
@@ -159,6 +159,8 @@ static void tick_do_periodic_broadcast(v
*/
static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
{
+ dev->next_event.tv64 = KTIME_MAX;
+
tick_do_periodic_broadcast();
/*
@@ -174,7 +176,7 @@ static void tick_handle_periodic_broadca
for (;;) {
ktime_t next = ktime_add(dev->next_event, tick_period);
- if (!clockevents_program_event(dev, next))
+ if (!clockevents_program_event(dev, next, ktime_get()))
return;
tick_do_periodic_broadcast();
}
@@ -294,17 +296,31 @@ cpumask_t *tick_get_broadcast_oneshot_ma
return &tick_broadcast_oneshot_mask;
}
+static int tick_broadcast_set_event(ktime_t expires, int force)
+{
+ struct clock_event_device *bc = tick_broadcast_device.evtdev;
+ ktime_t now = ktime_get();
+ int res;
+
+ for(;;) {
+ res = clockevents_program_event(bc, expires, now);
+ if (!res || !force)
+ return res;
+ now = ktime_get();
+ expires = ktime_add(now, ktime_set(0, bc->min_delta_ns));
+ }
+}
+
/*
* Reprogram the broadcast device:
*
* Called with tick_broadcast_lock held and interrupts disabled.
*/
-static int tick_broadcast_reprogram(int force)
+static int tick_broadcast_reprogram(void)
{
- struct clock_event_device *bc = tick_broadcast_device.evtdev;
- ktime_t tmp, expires = { .tv64 = KTIME_MAX };
+ ktime_t expires = { .tv64 = KTIME_MAX };
struct tick_device *td;
- int cpu, res;
+ int cpu;
/*
* Find the event which expires next:
@@ -319,13 +335,7 @@ static int tick_broadcast_reprogram(int
if (expires.tv64 == KTIME_MAX)
return 0;
- for(;;) {
- res = clockevents_program_event(bc, expires);
- if (!res || !force)
- return res;
- tmp = ktime_set(0, bc->min_delta_ns << 1);
- expires = ktime_add(ktime_get(), tmp);
- }
+ return tick_broadcast_set_event(expires, 0);
}
/*
@@ -333,14 +343,15 @@ static int tick_broadcast_reprogram(int
*/
static void tick_handle_oneshot_broadcast(struct clock_event_device *dev)
{
- ktime_t now;
struct tick_device *td;
- cpumask_t mask = CPU_MASK_NONE;
+ cpumask_t mask;
+ ktime_t now;
int cpu;
spin_lock(&tick_broadcast_lock);
-
again:
+ dev->next_event.tv64 = KTIME_MAX;
+ mask = CPU_MASK_NONE;
now = ktime_get();
/* Find all expired events */
for (cpu = first_cpu(tick_broadcast_oneshot_mask); cpu != NR_CPUS;
@@ -360,7 +371,7 @@ again:
* events. This happens in dyntick mode, as the
* maximum PIT delta is quite small.
*/
- if (tick_broadcast_reprogram(0))
+ if (tick_broadcast_reprogram())
goto again;
}
spin_unlock(&tick_broadcast_lock);
@@ -398,6 +409,8 @@ void tick_broadcast_oneshot_control(unsi
if (!cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
cpu_set(cpu, tick_broadcast_oneshot_mask);
clockevents_set_mode(dev, CLOCK_EVT_MODE_SHUTDOWN);
+ if (dev->next_event.tv64 < bc->next_event.tv64)
+ tick_broadcast_set_event(dev->next_event, 1);
}
} else {
if (cpu_isset(cpu, tick_broadcast_oneshot_mask)) {
@@ -408,8 +421,6 @@ void tick_broadcast_oneshot_control(unsi
}
}
- if (!cpus_empty(tick_broadcast_oneshot_mask))
- tick_broadcast_reprogram(1);
out:
spin_unlock_irqrestore(&tick_broadcast_lock, flags);
}
@@ -422,6 +433,7 @@ void tick_broadcast_setup_oneshot(struct
if (bc->mode != CLOCK_EVT_MODE_ONESHOT) {
bc->event_handler = tick_handle_oneshot_broadcast;
clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
+ bc->next_event.tv64 = KTIME_MAX;
}
}
Index: linux-2.6.20/include/linux/clockchips.h
===================================================================
--- linux-2.6.20.orig/include/linux/clockchips.h
+++ linux-2.6.20/include/linux/clockchips.h
@@ -128,7 +128,7 @@ extern void clockevents_set_mode(struct
extern int clockevents_register_notifier(struct notifier_block *nb);
extern void clockevents_unregister_notifier(struct notifier_block *nb);
extern int clockevents_program_event(struct clock_event_device *dev,
- ktime_t expires);
+ ktime_t expires, ktime_t now);
extern void clockevents_notify(unsigned long reason, void *arg);
Index: linux-2.6.20/kernel/time/tick-common.c
===================================================================
--- linux-2.6.20.orig/kernel/time/tick-common.c
+++ linux-2.6.20/kernel/time/tick-common.c
@@ -89,7 +89,7 @@ void tick_handle_periodic(struct clock_e
for (;;) {
ktime_t next = ktime_add(dev->next_event, tick_period);
- if (!clockevents_program_event(dev, next))
+ if (!clockevents_program_event(dev, next, ktime_get()))
return;
tick_periodic(cpu);
}
@@ -120,7 +120,7 @@ void tick_setup_periodic(struct clock_ev
clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
for (;;) {
- if (!clockevents_program_event(dev, next))
+ if (!clockevents_program_event(dev, next, ktime_get()))
return;
next = ktime_add(next, tick_period);
}
Index: linux-2.6.20/kernel/time/tick-oneshot.c
===================================================================
--- linux-2.6.20.orig/kernel/time/tick-oneshot.c
+++ linux-2.6.20/kernel/time/tick-oneshot.c
@@ -28,14 +28,15 @@
int tick_program_event(ktime_t expires, int force)
{
struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
+ ktime_t now = ktime_get();
while (1) {
- int ret = clockevents_program_event(dev, expires);
+ int ret = clockevents_program_event(dev, expires, now);
if (!ret || !force)
return ret;
- expires = ktime_add(expires,
- ktime_set(0, dev->min_delta_ns << 2));
+ now = ktime_get();
+ expires = ktime_add(now, ktime_set(0, dev->min_delta_ns));
}
}
@@ -48,7 +49,7 @@ void tick_setup_oneshot(struct clock_eve
{
newdev->event_handler = handler;
clockevents_set_mode(newdev, CLOCK_EVT_MODE_ONESHOT);
- clockevents_program_event(newdev, next_event);
+ clockevents_program_event(newdev, next_event, ktime_get());
}
/**
Index: linux-2.6.20/kernel/time/tick-sched.c
===================================================================
--- linux-2.6.20.orig/kernel/time/tick-sched.c
+++ linux-2.6.20/kernel/time/tick-sched.c
@@ -137,13 +137,15 @@ __setup("nohz=", setup_tick_nohz);
*/
void tick_nohz_update_jiffies(void)
{
- struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+ 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;
+ cpu_clear(cpu, nohz_cpu_mask);
now = ktime_get();
local_irq_save(flags);
@@ -161,17 +163,24 @@ void tick_nohz_update_jiffies(void)
void tick_nohz_stop_sched_tick(void)
{
unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
- struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+ struct tick_sched *ts;
ktime_t last_update, expires, now, delta;
-
- if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
- return;
+ int cpu;
local_irq_save(flags);
+ cpu = smp_processor_id();
+ ts = &per_cpu(tick_cpu_sched, cpu);
+
+ if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
+ goto end;
+
if (need_resched())
goto end;
+ cpu = smp_processor_id();
+ BUG_ON(local_softirq_pending());
+
now = ktime_get();
/*
* When called from irq_exit we need to account the idle sleep time
@@ -196,12 +205,20 @@ void tick_nohz_stop_sched_tick(void)
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 */
- if (!ts->tick_stopped && delta_jiffies == 1)
+ /*
+ * Do not stop the tick, if we are only one off
+ * or if the cpu is required for rcu
+ */
+ if (!ts->tick_stopped && (delta_jiffies == 1 || rcu_needs_cpu(cpu)))
goto out;
/* Schedule the tick, if we are at least one jiffie off */
if ((long)delta_jiffies >= 1) {
+
+ if (rcu_needs_cpu(cpu))
+ delta_jiffies = 1;
+ else
+ cpu_set(cpu, nohz_cpu_mask);
/*
* nohz_stop_sched_tick can be called several times before
* the nohz_restart_sched_tick is called. This happens when
@@ -237,6 +254,7 @@ void tick_nohz_stop_sched_tick(void)
* softirq.
*/
tick_do_update_jiffies64(ktime_get());
+ cpu_clear(cpu, nohz_cpu_mask);
}
raise_softirq_irqoff(TIMER_SOFTIRQ);
out:
@@ -253,7 +271,8 @@ end:
*/
void tick_nohz_restart_sched_tick(void)
{
- struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+ int cpu = smp_processor_id();
+ struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
unsigned long ticks;
ktime_t now, delta;
@@ -265,6 +284,7 @@ void tick_nohz_restart_sched_tick(void)
local_irq_disable();
tick_do_update_jiffies64(now);
+ cpu_clear(cpu, nohz_cpu_mask);
/* Account the idle time */
delta = ktime_sub(now, ts->idle_entrytime);
-
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