Currently we are iterating over all possible (currently four) bits of active_bases to see if corresponding clock bases are active. This is good enough for cases where 3 or 4 bases are used but if only 1 or 2 are used then it makes more sense to use ffs() to find the right bit directly.
Suggested-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Viresh Kumar viresh.kumar@linaro.org --- V3->Resend: s/__ffs/ffs in commit log :(
V2->V3: Use ffs() instead of __ffs() and decrement 'i' later.
V1->V2: Instead of removing active_bases use __ffs() on it to make loop more efficient.
kernel/hrtimer.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index acfef5f..2aad8a7 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -1265,6 +1265,7 @@ void hrtimer_interrupt(struct clock_event_device *dev) { struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); ktime_t expires_next, now, entry_time, delta; + unsigned long active_bases = cpu_base->active_bases; int i, retries = 0;
BUG_ON(!cpu_base->hres_active); @@ -1284,15 +1285,11 @@ retry: */ cpu_base->expires_next.tv64 = KTIME_MAX;
- for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { - struct hrtimer_clock_base *base; + while ((i = ffs(active_bases))) { + struct hrtimer_clock_base *base = cpu_base->clock_base + --i; struct timerqueue_node *node; ktime_t basenow;
- if (!(cpu_base->active_bases & (1 << i))) - continue; - - base = cpu_base->clock_base + i; basenow = ktime_add(now, base->offset);
while ((node = timerqueue_getnext(&base->active))) { @@ -1327,6 +1324,8 @@ retry:
__run_hrtimer(timer, &basenow); } + + active_bases &= ~(1 << i); }
/*