gh-150258: Show relative percentage on Tachyon flamegraph (GH-150266)
When running profiling, users rarely care about the global percentage of
the runtime. Often, they want to select a function and measure child
percentages relative to that.
This PR updates the flamegraph tooltips to show both "Percentage" and
"Relative Percentage" when the user clicks a specific function.
(cherry picked from commit fad0674605)
Co-authored-by: Eduardo Villalpando Mello <[email protected]>
Fix inverted flamegraph width
The inverted view used thread presence as a proxy for self time.
This missed self samples on C-level wrapper frames like _run_code,
where the node's thread always appears in its children too. Those
samples were silently dropped, causing the chart to render narrower
than full width. Now uses the explicit self field on each node
instead of the thread heuristic.
We already show self time in differential flamegraphs, but it should
be included in regular flamegraphs as well. Display the time spent
in the function body excluding callees, not just the total inclusive
time.
Differential flame graphs compare two profiling runs and highlight where
performance has changed. This makes it easier to detect regressions
introduced by code changes and to verify that optimizations have the
intended effect.
The visualization renders the current profile with frame widths
representing current time consumption. Color is then applied to show the
difference relative to the baseline profile: red gradients indicate
regressions, while blue gradients indicate improvements.
Some call paths may disappear entirely between profiles. These are
referred to as elided stacks and occur when optimizations remove code
paths or when certain branches stop executing. When elided stacks are
present, an "Elided" toggle is displayed, allowing the user to switch
between the main differential view and a view showing only the removed
paths.
Co-authored-by: Pablo Galindo Salgado <[email protected]>
