NAME

quark_time_to_wallclock — translate a time since boot to wallclock

SYNOPSIS

#include <quark.h>

u64
quark_time_to_wallclock(u64 time_since_boot);

DESCRIPTION

quark_time_to_wallclock translates time_since_boot from nanoseconds since boot to nanoseconds since the Unix epoch by adding the internal boottime epoch, see quark_get_boottime(3).

All times handed out by quark are suitable inputs: time of quark_event, proc_time_boot and exit_time_event of quark_process, as well as established_time and close_time of quark_socket. These fields are expressed as nanoseconds since boot since quark 0.8, in earlier versions they were nanoseconds since the Unix epoch and needed no translation.

Times since boot are immune to system clock changes, wallclock times are not. Translate at the last moment, when a time leaves the system for display or storage, and keep the epoch fresh with quark_update_boottime(3) if the clock may be stepped while running. Gradual corrections (slewing) adjust the wallclock and the boot clock at the same rate, leaving the epoch untouched, only a step moves it.

The KPROBE backend stamps times with a monotonic clock that does not advance during suspend, relayed as QQ_MONOTONIC on the opened queue's flags, see quark_queue_open(3). quark_time_to_wallclock applies unchanged, but the result lags the wallclock by the total suspended time, exactly as it did before quark 0.8. Users that care about suspend can detect QQ_MONOTONIC and compensate with the difference between CLOCK_BOOTTIME and CLOCK_MONOTONIC.

RETURN VALUES

time_since_boot expressed in nanoseconds since the Unix epoch.

SEE ALSO

quark_event_dump(3), quark_get_boottime(3), quark_process_iter(3), quark_process_lookup(3), quark_queue_block(3), quark_queue_close(3), quark_queue_default_attr(3), quark_queue_get_epollfd(3), quark_queue_get_event(3), quark_queue_get_stats(3), quark_queue_open(3), quark_update_boottime(3), quark(7), quark-btf(8), quark-mon(8), quark-test(8)

HISTORY

quark_time_to_wallclock appeared in quark 0.8, when all times handed out by quark switched from nanoseconds since the Unix epoch to nanoseconds since boot.