• Daniel Bristot de Oliveira's avatar
    tracing/osnoise: Add preempt and/or irq disabled options · b5dce200
    Daniel Bristot de Oliveira authored
    The osnoise workload runs with preemption and IRQs enabled in such
    a way as to allow all sorts of noise to disturb osnoise's execution.
    hwlat tracer has a similar workload but works with irq disabled,
    allowing only NMIs and the hardware to generate noise.
    
    While thinking about adding an options file to hwlat tracer to
    allow the system to panic, and other features I was thinking
    to add, like having a tracepoint at each noise detection, it
    came to my mind that is easier to make osnoise and also do
    hardware latency detection than making hwlat "feature compatible"
    with osnoise.
    
    Other points are:
     - osnoise already has an independent cpu file.
     - osnoise has a more intuitive interface, e.g., runtime/period vs.
       window/width (and people often need help remembering what it is).
     - osnoise: tracepoints
     - osnoise stop options
     - osnoise options file itself
    
    Moreover, the user-space side (in rtla) is simplified by reusing the
    existing osnoise code.
    
    Finally, people have been asking me about using osnoise for hw latency
    detection, and I have to explain that it was sufficient but not
    necessary. These options make it sufficient and necessary.
    
    Adding a Suggested-by Clark, as he often asked me about this
    possibility.
    
    Link: https://lkml.kernel.org/r/d9c6c19135497054986900f94c8e47410b15316a.1670623111.git.bristot@kernel.org
    
    Cc: Suggested-by: Clark Williams <williams@redhat.com>
    Cc: Juri Lelli <juri.lelli@redhat.com>
    Cc: Bagas Sanjaya <bagasdotme@gmail.com>
    Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Jonathan Corbet <corbet@lwn.net>
    Signed-off-by: default avatarDaniel Bristot de Oliveira <bristot@kernel.org>
    Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
    b5dce200
trace_osnoise.c 64 KB