I'm using ftrace to trace memory usage in applications I am running. I have no problem tracing sched and power events for tracking the scheduler and cpu frequency, but when it comes to tracking allocation of memory in my application I am not seeing any outpupt from the mem_buf events. Ftrace kmem events allow tracing of kernel memory usage just fine, but there are certain groups of ftracer events that provide no trace (it's not just mem_buf, but mem_buf is the group of events that I am focused on at the moment).
I enable the events via:
/sys/kernel/debug/tracing # echo 1 > events/mem_buf/enable
Which successfully enables all mem_buf events.
I turn on tracing, then run my application. The problem is that the events generate no output in the trace. Is there something additional that I need to configure in ftrace to enable these events?
/sys/kernel/debug/tracing # more trace
# tracer: nop
#
# entries-in-buffer/entries-written: 0/0 #P:8
