xrefcode.com / docs / cli / profile-diff

$ xref profile diff

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Usage
Arguments and options
Examples
Two recordings of the same process
Reading the output
Provenance

Compare two profiles by sample share: which functions got hotter or cooler. Two recordings of the same binary are compared function by function; with --other NEW_BINARY the second profile is of another build, and functions are paired with match (heuristic, and marked as such).

Usage

xref profile diff [OPTIONS] <BEFORE> <AFTER>

Arguments and options

Arguments

<BEFORE>

The earlier .xprof recording.

<AFTER>

The later .xprof recording.

Options

--other <OTHER>

Binary AFTER was recorded from, when it is another build; functions are then paired heuristically.

--top <TOP>

Number of rows to print.

default 30

--json

Print the comparison as JSON.

--by <BY>

What a row aggregates [possible values: function].

default function

--min-delta <MIN_DELTA>

Omit rows whose share changed by fewer percentage points than this.

default 0

Examples

Two recordings of the same process

Two one-second live profile recordings of the same ripgrep process:

Command

$ xref -b rg profile diff rg.xprof rg-2.xprof --top 6

Output

sample-share delta; cross-build pairs are heuristic; shared modules omitted
  +1.12%  0x42f380 -> 0x42f380 [same_image]
  -0.71%  0x4302b0 -> 0x4302b0 [same_image]
  +0.43%  0x430060 -> 0x430060 [same_image]
  -0.13%  0x4752a0 -> 0x4752a0 [same_image]
  -0.11%  0x4307b0 -> 0x4307b0 [same_image]
  -0.09%  0x10b0c0 -> 0x10b0c0 [same_image]

stderr

xref: load 2.4ms, total 31.7ms

Reading the output

Each row: the change in sample share, the function in the first and the second profile (- when one side has no counterpart), and how they were paired: same_image, heuristic (cross-build match) or unmatched.
Shares are normalized by each profile's sample count, so recordings of different lengths compare directly. Small deltas between two runs of the same workload, as here, are sampling noise.

Provenance

Recorded with a development build of xref after 0.4.0 on Linux x86-64, on rg = ripgrep 14.1.1 (official stripped release). Output is unchanged except that whitespace at the end of each line and empty lines at the end of the output are removed; long outputs are cut where marked.

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