ftrace_timestamp 1187 include/linux/sched.h unsigned long long ftrace_timestamp; ftrace_timestamp 404 kernel/trace/fgraph.c prev->ftrace_timestamp = timestamp; ftrace_timestamp 407 kernel/trace/fgraph.c if (!next->ftrace_timestamp) ftrace_timestamp 414 kernel/trace/fgraph.c timestamp -= next->ftrace_timestamp; ftrace_timestamp 467 kernel/trace/fgraph.c t->ftrace_timestamp = 0;