• Steven Rostedt (Red Hat)'s avatar
    tracing: Add function-trace option to disable function tracing of latency tracers · 328df475
    Steven Rostedt (Red Hat) authored
    
    
    Currently, the only way to stop the latency tracers from doing function
    tracing is to fully disable the function tracer from the proc file
    system:
    
      echo 0 > /proc/sys/kernel/ftrace_enabled
    
    This is a big hammer approach as it disables function tracing for
    all users. This includes kprobes, perf, stack tracer, etc.
    
    Instead, create a function-trace option that the latency tracers can
    check to determine if it should enable function tracing or not.
    This option can be set or cleared even while the tracer is active
    and the tracers will disable or enable function tracing depending
    on how the option was set.
    
    Instead of using the proc file, disable latency function tracing with
    
      echo 0 > /debug/tracing/options/function-trace
    
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Clark Williams <williams@redhat.com>
    Cc: John Kacur <jkacur@redhat.com>
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
    328df475
trace.h 30 KB