* Vince Do ([email protected]) wrote: > Hello, > > I was wondering if you can give me more information on how LTTng the > timestamps are taken for a kernel trace, I have read in this article > (Combined Tracing of the Kernel and Applications with LTTng at Linux > Symposium 2009) that TSC and the command rdtsc are used, but the article is > old (2009) and I would like to know if there are been any changes.
lttng uses the Linux kernel CLOCK_MONOTONIC clock, read through clock_gettime() in user-space, and from ktime_get() in the kernel. On x86 systems where TSC are synchronized and constant, it uses rdtsc, scales that value to nanoseconds, and adds an offset. The fall-back is usually the HPET timer on x86. Thanks, Mathieu > > Regards, > > > > Vincenzo Do > _______________________________________________ > lttng-dev mailing list > [email protected] > http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev -- Mathieu Desnoyers Operating System Efficiency R&D Consultant EfficiOS Inc. http://www.efficios.com _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
