• Steven Rostedt's avatar
    ftrace: trace preempt off critical timings · 6cd8a4bb
    Steven Rostedt authored
    Add preempt off timings. A lot of kernel core code is taken from the RT patch
    latency trace that was written by Ingo Molnar.
    This adds "preemptoff" and "preemptirqsoff" to /debugfs/tracing/available_tracers
    Now instead of just tracing irqs off, preemption off can be selected
    to be recorded.
    When this is selected, it shares the same files as irqs off timings.
    One can either trace preemption off, irqs off, or one or the other off.
    By echoing "preemptoff" into /debugfs/tracing/current_tracer, recording
    of preempt off only is performed. "irqsoff" will only record the time
    irqs are disabled, but "preemptirqsoff" will take the total time irqs
    or preemption are disabled. Runtime switching of these options is now
    supported by simpling echoing in the appropriate trace name into
    Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>