I think this looks very reasonable in general in terms of the UI side.

That said (and I realize that this PR in particular doesn't change much in this regard, apart from in the ftrace event details panel) but I'm not a huge fan of the fact that the query is abstracted behind the getArgs function.

I'd like to have the option to fetch everything in one go like:

SELECT
   *,
   print_args(arg_set_id) AS argsJson
FROM foo

Then have a synchronous helper to turn this into this into a tree of ArgDict for printing and processing.

In general the SQL helper functions like this usually end up pulling duplicate data and slowing things down. I'll concede that this args example is quite clean but I think as a general principle they should be avoided.

Again as this PR doesn't really change this much (apart from in the ftrace details panel), I think we can tackle this in a different PR, but I thought I'd mention it here.