• Steven Rostedt (VMware)'s avatar
    tracing: Fix hwlat kthread migration · 79c6f448
    Steven Rostedt (VMware) authored
    The hwlat tracer creates a kernel thread at start of the tracer. It is
    pinned to a single CPU and will move to the next CPU after each period of
    running. If the user modifies the migration thread's affinity, it will not
    change after that happens.
    
    The original code created the thread at the first instance it was called,
    but later was changed to destroy the thread after the tracer was finished,
    and would not be created until the next instance of the tracer was
    established. The code that initialized the affinity was only called on the
    initial instantiation of the tracer. After that, it was not initialized, and
    the previous affinity did not match the current newly created one, making
    it appear that the user modified the thread's affinity when it did not, and
    the thread failed to migrate again.
    
    Cc: stable@vger.kernel.org
    Fixes: 0330f7aa ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs")
    Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
    79c6f448
trace_hwlat.c 16.7 KB