On Thu, 27 Mar 2014, Viresh Kumar wrote:
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
V1->V2: Instead of removing active_bases use __ffs() on it to make loop more efficient.
I tried to use for_each_set_bit() first and then it looked overdone. And so used a simple form, __ffs() with some code to clear bits.
kernel/hrtimer.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index acfef5f..ea90228 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))) {
What if this is a spurious interrupt and active_bases is 0?
Thanks,
tglx