Re: [PATCH 1/3] clockevents: Retry programming min delta up to 10 times

From: Matt Redfearn
Date: Thu Oct 19 2017 - 09:23:11 EST




On 19/10/17 13:43, Thomas Gleixner wrote:
On Thu, 19 Oct 2017, Matt Redfearn wrote:
unsigned long long clc;
int64_t delta;
+ int i;
- delta = dev->min_delta_ns;
- dev->next_event = ktime_add_ns(ktime_get(), delta);
+ for (i = 0;;) {
Bah. What's wrong with

for (i = 0; i < 10; i++) {

....
if (!(dev->set_next_event((unsigned long) clc, dev))
return 0;
}
return -ETIME;

Hmm?

Sure, can make it like that.

+ delta = dev->min_delta_ns;
+ dev->next_event = ktime_add_ns(ktime_get(), delta);
- if (clockevent_state_shutdown(dev))
- return 0;
+ if (clockevent_state_shutdown(dev))
+ return 0;
- dev->retries++;
- clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
- return dev->set_next_event((unsigned long) clc, dev);
+ dev->retries++;
+ clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
I'd rather make that:

delta = 0;
for (i = 0; i < 10; i++) {
delta += dev->min_delta_ns;
dev->next_event = ktime_add_ns(ktime_get(), delta);
clc = .....
.....

That makes it more likely to succeed fast. Hmm?

That will set the target time to increasing multiples of min_delta_ns in the future, right? Sure, it should make it succeed faster - I'll make it like that. Are you OK with the arbitrarily chosen 10 retries?

Thanks,
Matt


Thanks,

tglx