On Fri, 11 Mar 2005, john stultz wrote:
> +/* get_lowres_timestamp():
> + * Returns a low res timestamp.
> + * (ie: the value of system_time as calculated at
> + * the last invocation of timeofday_periodic_hook() )
> + */
> +nsec_t get_lowres_timestamp(void)
> +{
> + nsec_t ret;
> + unsigned long seq;
> + do {
> + seq = read_seqbegin(&system_time_lock);
> +
> + /* quickly grab system_time*/
> + ret = system_time;
> +
> + } while (read_seqretry(&system_time_lock, seq));
> +
> + return ret;
> +}
On 64 bit platforms this could simply be a macro accessing "system time".
> +/* do_gettimeofday():
> + * Returns the time of day
> + */
> +void do_gettimeofday(struct timeval *tv)
> +{
> + nsec_t wall, sys;
> + unsigned long seq;
> +
> + /* atomically read wall and sys time */
> + do {
> + seq = read_seqbegin(&system_time_lock);
> +
> + wall = wall_time_offset;
> + sys = __monotonic_clock();
> +
> + } while (read_seqretry(&system_time_lock, seq));
> +
> + /* add them and convert to timeval */
> + *tv = ns2timeval(wall+sys);
> +}
> +EXPORT_SYMBOL(do_gettimeofday);
Good.
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