Thanks for the detailed comment!
> overwhelmingly it gets used because of their integration with the exceptionally simple JSON tracing format
So in the open source community maybe, but it's use in the Android organization in Google is ubiquitous. Obviously, people outside the company don't see this, but we do. And I think even outside, there are a fair number of people using it for Android/Linux related things.
> UI should just get split off into its own thing
By split off, do you mean from a "branding" perspective? Or like separate as its own technical entity? If the former, maybe a reasonable idea but I think rebranding now would lose a lot of the "name recognition" which comes with the Perfetto name.
If the latter, there are two problems as I see it:
1) The UI uses the trace processor as its "backend". And the trace processor is deeply integrated into the rest of Perfetto.
2) If it's split off, who maintains it?
> it's just very strange to me that the UI will always be showing things like "syscall trace" or "connect a device" when I am looking at GPU kernels or network spans
Only in the recording page right? At least from the timeline perspective, everything should be only related with your trace. And in practice, we've been working on the last year or so on "pluginizing" the UI - basically turning the UI into a modular set of components and separating the "core" of the UI (which doesn't know anything about Android or Chrome and reasons purely in terms of "tracks", "slices", "counters" etc).
So it's actually possible to just totally remove all the parts of the UI you don't care about by going around and turning off things on the "Plugins" page. Obviously, most people are not going to do that but maybe we can offer them a "one click" solution when they first open the UI to do so?
> because I get the impression that they don't even really particularly like supporting what everyone else is using it for.
This is not true, we actually really do like supporting it for other people. It's just that sometimes what we want to do for open source conflicts with what Google wants from us as a team in prioritisation. I actually talked about this in detail recently: https://lalitm.com/perfetto-oss-company-prio/
> Also, I repeat this a lot, but I think a lot of profiling tools could stand to learn things from Apple's Instruments.
At least from the Android system profiling level, we do look at Apple Instruments! And yes there are things we can learn from them! But I don't think the gap is as large as you suggest (see below).
> It's even weirder and more proprietary in the ways I mentioned above while also not having any sort of import feature
So this is one reason Apple Instruments is so good at what it does: it's a focused profilier helping you debug problems on Apple devices and so they can deeply bake that intelligence in the tool. With Perfetto, I think if you record a real Perfetto Android trace (instead of generating a JSON one) you do actually get a much more "intelligence" (even though it's not as much as Apple).
For a synthetic trace, it's very hard for us to offer the experience because we don't know the same "happy debugging paths": we have no idea how you want to look at the data. How are is the UI meant to know on a random trace what sort of "problems" the user is looking for?
Would love to hear your thoughts on this because it's not like it's a problem we're not aware of, it's more, we think it's a super hard problem with no easy solution.
> but it is exceptionally good at common tasks like "zoom into this region"
At least for this example, Perfetto has this feature: when zoomed out, click on a slice in an area you want to zoom to and then press "f". It wil snap zoom into that section
> or "let me quickly jump to the part of this call stack that is a problem"
I think we also have this but it's a few more clicks than I think we should have. Definitely something we should close the gap on!
