On Tue, 14 Jul 2020 15:18:01 +0300 Itai Handler <itai.handler@xxxxxxxxx> wrote: > I tried "ftrace=function_graph ftrace_graph_filter=workqueue_prepare_cpu", > however, the trace appears to be empty. > The function workqueue_prepare_cpu is not defined inline nor notrace. > > Please see log below: > # mount -t debugfs none /sys/kernel/debug > # cd /sys/kernel/debug/tracing/ > # cat trace > # tracer: function_graph > # > # CPU DURATION FUNCTION CALLS > # | | | | | | | > # cat set_graph_function > workqueue_prepare_cpu > # cat tracing_on > 1 > > Do you have any idea why it's empty? Hmm, does the place in question happen before ftrace is initialized? That is, where do you see the message that has something like this: ftrace: allocating 41803 entries in 164 pages ftrace: allocated 164 pages with 3 groups -- Steve
