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A better explanation for change in differentials #294

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A better explanation for change in differentials #294

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8973a5c
A better explanation for change in differentials.
pythonspeed May 26, 2023
4c6b42b
Tweak to output.
pythonspeed May 31, 2023
3f7ed42
"unchanged" is inaccurate for non-final frames, since Inferno doesn't…
pythonspeed May 31, 2023
9118bd4
Merge remote-tracking branch 'origin/main' into 293-better-differenti…
pythonspeed Aug 4, 2024
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2 changes: 1 addition & 1 deletion flamegraph
Open in desktop
Submodule flamegraph updated 34 files
+1 −2 README.md
+15 −74 flamegraph.pl
+3 −9 stackcollapse-bpftrace.pl
+0 −61 stackcollapse-faulthandler.pl
+0 −145 stackcollapse-ibmjava.pl
+7 −15 stackcollapse-instruments.pl
+16 −21 stackcollapse-perf.pl
+1 −1 stackcollapse-pmc.pl
+0 −103 stackcollapse-vtune-mc.pl
+3 −3 stackcollapse-xdebug.php
+10 −10 test/results/perf-dd-stacks-01-collapsed-addrs.txt
+10 −10 test/results/perf-dd-stacks-01-collapsed-all.txt
+10 −10 test/results/perf-dd-stacks-01-collapsed-jit.txt
+10 −10 test/results/perf-dd-stacks-01-collapsed-kernel.txt
+10 −10 test/results/perf-dd-stacks-01-collapsed-pid.txt
+10 −10 test/results/perf-dd-stacks-01-collapsed-tid.txt
+7 −7 test/results/perf-java-faults-01-collapsed-addrs.txt
+7 −7 test/results/perf-java-faults-01-collapsed-all.txt
+7 −7 test/results/perf-java-faults-01-collapsed-jit.txt
+7 −7 test/results/perf-java-faults-01-collapsed-kernel.txt
+9 −9 test/results/perf-java-faults-01-collapsed-pid.txt
+9 −9 test/results/perf-java-faults-01-collapsed-tid.txt
+26 −26 test/results/perf-java-stacks-01-collapsed-pid.txt
+26 −26 test/results/perf-java-stacks-01-collapsed-tid.txt
+1 −1 test/results/perf-java-stacks-02-collapsed-pid.txt
+1 −1 test/results/perf-java-stacks-02-collapsed-tid.txt
+45 −45 test/results/perf-rust-Yamakaky-dcpu-collapsed-addrs.txt
+45 −45 test/results/perf-rust-Yamakaky-dcpu-collapsed-all.txt
+45 −45 test/results/perf-rust-Yamakaky-dcpu-collapsed-jit.txt
+45 −45 test/results/perf-rust-Yamakaky-dcpu-collapsed-kernel.txt
+45 −45 test/results/perf-rust-Yamakaky-dcpu-collapsed-pid.txt
+45 −45 test/results/perf-rust-Yamakaky-dcpu-collapsed-tid.txt
+191 −191 test/results/perf-vertx-stacks-01-collapsed-pid.txt
+191 −191 test/results/perf-vertx-stacks-01-collapsed-tid.txt
35 changes: 22 additions & 13 deletions src/flamegraph/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -616,21 +616,30 @@ where
"{} ({} {}, {:.2}%)",
function, samples_txt, opt.count_name, pct
),
// Special case delta == 0 so we don't format percentage with a + sign.
Some(delta) if delta == 0 => write!(
buffer,
"{} ({} {}, {:.2}%; 0.00%)",
function, samples_txt, opt.count_name, pct,
),
Some(mut delta) => {
if opt.negate_differentials {
delta = -delta;
}
let delta_pct = (100 * delta) as f64 / (timemax as f64 * opt.factor);
Some(delta) => {
let samples = frame.end_time as isize - frame.start_time as isize;
let (old, new) = if opt.negate_differentials {
(samples, samples - delta)
} else {
(samples - delta, samples)
};
let change = match (old, new) {
(0, _) => "all newly added".to_string(),
(_, 0) => "were all removed".to_string(),
Comment on lines +627 to +628
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I wonder if these labels still make sense if negate_differentials is on.

(x, y) if x == y => "".to_string(),
(old, new) => {
let (ratio, compared_to) = if opt.negate_differentials {
(old as f64 / new as f64, "new")
} else {
(new as f64 / old as f64, "old")
};
format!(" = {ratio:.3} × {compared_to} {}", opt.count_name)
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I'm not sure I follow the phrasing here. If, for example, we spend 2x as many samples in some frame, this will look like (I think):

= 2 × old cycles

Which I think is maybe overly concise. It doesn't include the function name (is that printed elsewhere?), and the old or new sample counts. I think we'll want to include at least the function name and one of the two absolute numbers. I'm also not sure if "old" and "new" are understandable labels in this instance (esp. for negate_differentials) — they may even be unnecessary. I think "2×cycles" may actually be sufficient.

}
};
write!(
buffer,
"{} ({} {}, {:.2}%; {:+.2}%)",
function, samples_txt, opt.count_name, pct, delta_pct
"{} ({} {} {}, {:.2}%)",
function, samples_txt, opt.count_name, change, pct
)
}
}
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