• Steven Rostedt (Red Hat)'s avatar
    tracing: Consolidate max_tr into main trace_array structure · 12883efb
    Steven Rostedt (Red Hat) authored
    Currently, the way the latency tracers and snapshot feature works
    is to have a separate trace_array called "max_tr" that holds the
    snapshot buffer. For latency tracers, this snapshot buffer is used
    to swap the running buffer with this buffer to save the current max
    The only items needed for the max_tr is really just a copy of the buffer
    itself, the per_cpu data pointers, the time_start timestamp that states
    when the max latency was triggered, and the cpu that the max latency
    was triggered on. All other fields in trace_array are unused by the
    max_tr, making the max_tr mostly bloat.
    This change removes the max_tr completely, and adds a new structure
    called trace_buffer, that holds the buffer pointer, the per_cpu data
    pointers, the time_start timestamp, and the cpu where the latency occurred.
    The trace_array, now has two trace_buffers, one for the normal trace and
    one for the max trace or snapshot. By doing this, not only do we remove
    the bloat from the max_trace but the instances of traces can now use
    their own snapshot feature and not have just the top level global_trace have
    the snapshot feature and latency tracers for itself.
    Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
trace.h 29.4 KB