about `--pevent:time-zero`

[liusy58]

Hi, sir, sorry to disturb you again, but I cannot understand what is exactly --pevent:time-shift --pevent:time-mult``--pevent:time-zero usage?

[markus-metzger]

See doc/howto_capture.md:

Sideband and trace are time-correlated. Since Intel PT and perf use different
time domains, we need a few parameters to translate between the two domains.
The parameters can be found in struct perf_event_mmap_page, which is declared
in /usr/include/linux/perf_event.h:

• time_shift
• time_mult
• time_zero

The header also documents how to calculate TSC from perf_event timestamps.

The ptdump and ptxed sample tools do this translation but we need to supply the
parameters via corresponding options:

• --pevent:time-shift
• --pevent:time-mult
• --pevent:time-zero

[liusy58]

Let me have a look. Thx.