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| author |   Frederic Weisbecker <fweisbec@gmail.com> | 2015-08-18 16:18:29 +0200 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2015-08-18 18:36:59 +0200 |
| commit | b48362d8aaf32aeb4a75f5c556c652ffeeb1be5d (patch) | |
| tree | 0becbe13c29d0718ab7120565d6cb2ba039feeee /kernel/time/hrtimer.c | |
| parent | hrtimer: Simplify get_target_base() by returning current base (diff) | |
| download | linux-dev-b48362d8aaf32aeb4a75f5c556c652ffeeb1be5d.tar.xz linux-dev-b48362d8aaf32aeb4a75f5c556c652ffeeb1be5d.zip | |
hrtimer: Unconfuse switch_hrtimer_base() a bit
The variable called "this_base" is confusing because its name suggests
it's of "struct hrtimer_clock_base" type, along with "base" and "new_base"
which doesn't help understanding this complicated function.
Make its name clearer and fix the misleading comment while at it.
[ tglx: Fixed the comment for real ]
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1439907509-9553-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time/hrtimer.c')
| -rw-r--r-- | kernel/time/hrtimer.c | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index f9eb21ba3af6..5c4fe50e47d3 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -196,18 +196,27 @@ struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, #endif /* - * Switch the timer base to the current CPU when possible. + * We switch the timer base to a power-optimized selected CPU target, + * if: + * - NO_HZ_COMMON is enabled + * - timer migration is enabled + * - the timer callback is not running + * - the timer is not the first expiring timer on the new target + * + * If one of the above requirements is not fulfilled we move the timer + * to the current CPU or leave it on the previously assigned CPU if + * the timer callback is currently running. */ static inline struct hrtimer_clock_base * switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base, int pinned) { - struct hrtimer_cpu_base *new_cpu_base, *this_base; + struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base; struct hrtimer_clock_base *new_base; int basenum = base->index; - this_base = this_cpu_ptr(&hrtimer_bases); - new_cpu_base = get_target_base(this_base, pinned); + this_cpu_base = this_cpu_ptr(&hrtimer_bases); + new_cpu_base = get_target_base(this_cpu_base, pinned); again: new_base = &new_cpu_base->clock_base[basenum]; @@ -229,19 +238,19 @@ again: raw_spin_unlock(&base->cpu_base->lock); raw_spin_lock(&new_base->cpu_base->lock); - if (new_cpu_base != this_base && + if (new_cpu_base != this_cpu_base && hrtimer_check_target(timer, new_base)) { raw_spin_unlock(&new_base->cpu_base->lock); raw_spin_lock(&base->cpu_base->lock); - new_cpu_base = this_base; + new_cpu_base = this_cpu_base; timer->base = base; goto again; } timer->base = new_base; } else { - if (new_cpu_base != this_base && + if (new_cpu_base != this_cpu_base && hrtimer_check_target(timer, new_base)) { - new_cpu_base = this_base; + new_cpu_base = this_cpu_base; goto again; } } |