Stack graph usage in the timeline after the activity graph with CPU usage

[canova]

After we are done with changing the activity graph to have height depending on the CPU usage of the thread, we are not going to need the stack graph too much. Also we believe that having two radio buttons for different graphs are a bit confusing for the users. It would be great if we can find a better solution.

We've discussed this in our weekly team meeting, and we've came up with a plan for the future use of the stack graph. For some cases we are going to remove it, but for other cases like importers, we are going to keep them.

So, the end goal is:

• If the profile includes CPU usage values:
  • Don't show the radio buttons and only present the activity graph in the timeline.
    If people really need to look at the stack heights, they can still find it on the Stack Chart panel.
• If the profile doesn't include CPU usage values:
  • If threads have category information:
    • Show the activity graph.
  • If threads don't have the category information (e.g. linux perf and instruments imports):
    • Show the stack graph directly because activity graph will just be a block of gray area without an insight.

Let me know what you think!

[gregtatum]

Thanks for typing up the decisions here!

Also we believe that having two radio buttons for different graphs are a bit confusing for the users.

I agree.

If the profile includes CPU usage values:
Don't show the radio buttons and only present the activity graph in the timeline.
If people really need to look at the stack heights, they can still find it on the Stack Chart panel.

Another option would be to add a toggle to the context menu, it wouldn't really take up any UI space.

If threads don't have the category information (e.g. linux perf and instruments imports):
Show the stack graph directly because activity graph will just be a block of gray area without an insight.

Thanks, this is a valid use case that's nice to support and will give me excuses to contribute importers.

If people really need to look at the stack heights, they can still find it on the Stack Chart panel.

The one piece of parity that will be missed is that the stack height graph shows sampling rates really well. There are a few suggestions in #2962 that might provide that information.

[canova]

Thanks for the feedback @gregtatum!

If the profile includes CPU usage values:
Don't show the radio buttons and only present the activity graph in the timeline.
If people really need to look at the stack heights, they can still find it on the Stack Chart panel.

Another option would be to add a toggle to the context menu, it wouldn't really take up any UI space.

Yes, I think this is also another option. While talking, we didn't want to display these radio buttons at all because if they see the radio buttons for this case and see them missing for the CPU usage case, users could think that this feature is missing on the profiles with CPU usage values.
But I'm not sure how likely non-gecko developers will interact with older profiles (or profiles that don't include CPU usage values). I think it's mostly a concern for web developer user base and not that important for gecko developers. What do you think?

If threads don't have the category information (e.g. linux perf and instruments imports):
Show the stack graph directly because activity graph will just be a block of gray area without an insight.

Thanks, this is a valid use case that's nice to support and will give me excuses to contribute importers.

🎉 🎉

If people really need to look at the stack heights, they can still find it on the Stack Chart panel.

The one piece of parity that will be missed is that the stack height graph shows sampling rates really well. There are a few suggestions in #2962 that might provide that information.

Yeah, this seems like a problem we should fix. I guess people can still see the sampling rate with the little sample squares under the activity graph now (the ones in the CPU usage deploy preview). But that will still be missing in the stack chart. It would be good to include this information there as well. Thanks for pointing that out!

[gregtatum]

But I'm not sure how likely non-gecko developers will interact with older profiles (or profiles that don't include CPU usage values). I think it's mostly a concern for web developer user base and not that important for gecko developers. What do you think?

Having good default heuristics for showing something is nice, but it's also nice to have a consistent place that the toggle will show up, e.g. in the context menu.