• Dmitrii Dolgov's avatar
    io_uring: add set of tracing events · b345d88d
    Dmitrii Dolgov authored
    To trace io_uring activity one can get an information from workqueue and
    io trace events, but looks like some parts could be hard to identify via
    this approach. Making what happens inside io_uring more transparent is
    important to be able to reason about many aspects of it, hence introduce
    the set of tracing events.
    
    All such events could be roughly divided into two categories:
    
    * those, that are helping to understand correctness (from both kernel
      and an application point of view). E.g. a ring creation, file
      registration, or waiting for available CQE. Proposed approach is to
      get a pointer to an original structure of interest (ring context, or
      request), and then find relevant events. io_uring_queue_async_work
      also exposes a pointer to work_struct, to be able to track down
      corresponding workqueue events.
    
    * those, that provide performance related information. Mostly it's about
      events that change the flow of requests, e.g. whether an async work
      was queued, or delayed due to some dependencies. Another important
      case is how io_uring optimizations (e.g. registered files) are
      utilized.
    Signed-off-by: default avatarDmitrii Dolgov <9erthalion6@gmail.com>
    Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    b345d88d