Re: [uml-devel] [PATCH v4] um: Switch clocksource to hrtimers

[Richard Weinberger <richard@nod.at>]

Am 02.11.2015 um 17:16 schrieb Anton Ivanov:
> -void idle_sleep(unsigned long long nsecs)
> +/**
> + * os_idle_sleep() - sleep for a given time of nsecs
> + * @nsecs: nanoseconds to sleep
> + */
> +void os_idle_sleep(unsigned long long nsecs)
>  {
>  	struct timespec ts;
>  
> -	/*
> -	 * nsecs can come in as zero, in which case, this starts a
> -	 * busy loop.  To prevent this, reset nsecs to the tick
> -	 * interval if it is zero.
> -	 */
> -	if (nsecs == 0)
> -		nsecs = UM_NSEC_PER_SEC / UM_HZ;
> +	if (nsecs <= 0) {
> +		return;
> +	}
>  
> -	nsecs = sleep_time(nsecs);
> -	ts = ((struct timespec) { .tv_sec	= nsecs / UM_NSEC_PER_SEC,
> -				  .tv_nsec	= nsecs % UM_NSEC_PER_SEC });
> +	ts = ((struct timespec) {
> +			.tv_sec  = nsecs / UM_NSEC_PER_SEC,
> +			.tv_nsec = nsecs % UM_NSEC_PER_SEC
> +	});
>  
> -	if (nanosleep(&ts, &ts) == 0)
> +	if (clock_nanosleep(CLOCK_MONOTONIC, 0, &ts, NULL)) {
>  		deliver_alarm();
> -	after_sleep_interval(&ts);
> +	}

Hmm, now this function sleeps at most nsecs. If it is interrupted
the alarm is delivered.
Why only upon interruption and not also if clock_nanosleep()
completes?

Thanks,
//richard

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