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tick/broadcast: Check for hrtimer broadcast active early

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If the current cpu is the one which has the hrtimer based broadcast
queued then we better return busy immediately instead of going through
loops and hoops to figure that out.

[ Split out from a larger combo patch ]

Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
This commit is contained in:
Thomas Gleixner 2015-07-07 16:43:04 +02:00
parent 0cc5281aa5
commit d5113e13a5
1 changed files with 26 additions and 10 deletions
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36
kernel/time/tick-broadcast.c
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@ -705,6 +705,17 @@ int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
cpu = smp_processor_id();
if (state == TICK_BROADCAST_ENTER) {
/*
* If the current CPU owns the hrtimer broadcast
* mechanism, it cannot go deep idle and we do not add
* the CPU to the broadcast mask. We don't have to go
* through the EXIT path as the local timer is not
* shutdown.
*/
ret = broadcast_needs_cpu(bc, cpu);
if (ret)
goto out;
/*
* If the broadcast device is in periodic mode, we
* return.
@ -718,7 +729,10 @@ int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_oneshot_mask)) {
WARN_ON_ONCE(cpumask_test_cpu(cpu, tick_broadcast_pending_mask));
/* Conditionally shut down the local timer. */
broadcast_shutdown_local(bc, dev);
/*
* We only reprogram the broadcast timer if we
* did not mark ourself in the force mask and
@ -733,18 +747,20 @@ int __tick_broadcast_oneshot_control(enum tick_broadcast_state state)
ret = -EBUSY;
} else if (dev->next_event.tv64 < bc->next_event.tv64) {
tick_broadcast_set_event(bc, cpu, dev->next_event);
/*
* In case of hrtimer broadcasts the
* programming might have moved the
* timer to this cpu. If yes, remove
* us from the broadcast mask and
* return busy.
*/
ret = broadcast_needs_cpu(bc, cpu);
if (ret) {
cpumask_clear_cpu(cpu,
tick_broadcast_oneshot_mask);
}
}
}
/*
* If the current CPU owns the hrtimer broadcast
* mechanism, it cannot go deep idle and we remove the
* CPU from the broadcast mask. We don't have to go
* through the EXIT path as the local timer is not
* shutdown.
*/
ret = broadcast_needs_cpu(bc, cpu);
if (ret)
cpumask_clear_cpu(cpu, tick_broadcast_oneshot_mask);
} else {
if (cpumask_test_and_clear_cpu(cpu, tick_broadcast_oneshot_mask)) {
clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);