Re: [RFC v3] io_uring: add set of tracing events

[Jens Axboe <axboe@kernel.dk>]

On 10/15/19 11:02 AM, Dmitrii Dolgov wrote:
> 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.

Looks good to me, I've applied it for some testing. Thanks!

-- 
Jens Axboe