[RFC] perf script: add flamegraph.py script

[Andreas Gerstmayr]

This script works in tandem with d3-flame-graph to generate flame graphs
from perf. It supports two output formats: JSON and HTML (the default).
The HTML format will look for a standalone d3-flame-graph template file in
/usr/share/d3-flame-graph/template.html and fill in the collected stacks.

Usage:

    perf script flamegraph -a -F 99 sleep 60

Alternative usage:

    perf record -a -g -F 99 sleep 60
    perf script report flamegraph

Signed-off-by: Andreas Gerstmayr <agerstmayr@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
---

I'm currently preparing packages for d3-flame-graph. For Fedora, the copr
at
https://copr.fedorainfracloud.org/coprs/agerstmayr/reviews/package/js-d3-flame-graph/
can be installed, or alternatively the prebuilt standalone d3-flame-graph
template can be downloaded from
https://raw.githubusercontent.com/andreasgerstmayr/specs/master/reviews/js-d3-flame-graph/template.html
and moved into /usr/share/d3-flame-graph/template.html

 .../perf/scripts/python/bin/flamegraph-record |   2 +
 .../perf/scripts/python/bin/flamegraph-report |   3 +
 tools/perf/scripts/python/flamegraph.py       | 117 ++++++++++++++++++
 3 files changed, 122 insertions(+)
 create mode 100755 tools/perf/scripts/python/bin/flamegraph-record
 create mode 100755 tools/perf/scripts/python/bin/flamegraph-report
 create mode 100755 tools/perf/scripts/python/flamegraph.py

diff --git a/tools/perf/scripts/python/bin/flamegraph-record b/tools/perf/scripts/python/bin/flamegraph-record
new file mode 100755
index 000000000000..725d66e71570
--- /dev/null
+++ b/tools/perf/scripts/python/bin/flamegraph-record
@@ -0,0 +1,2 @@
+#!/usr/bin/sh
+perf record -g "$@"
diff --git a/tools/perf/scripts/python/bin/flamegraph-report b/tools/perf/scripts/python/bin/flamegraph-report
new file mode 100755
index 000000000000..b1a79afd903b
--- /dev/null
+++ b/tools/perf/scripts/python/bin/flamegraph-report
@@ -0,0 +1,3 @@
+#!/usr/bin/sh
+# description: create flame graphs
+perf script -s "$PERF_EXEC_PATH"/scripts/python/flamegraph.py -- "$@"
diff --git a/tools/perf/scripts/python/flamegraph.py b/tools/perf/scripts/python/flamegraph.py
new file mode 100755
index 000000000000..2e9139ef2c4a
--- /dev/null
+++ b/tools/perf/scripts/python/flamegraph.py
@@ -0,0 +1,117 @@
+# flamegraph.py - create flame graphs from perf samples
+# SPDX-License-Identifier: GPL-2.0
+#
+# Usage:
+#
+#  perf record -a -g -F 99 sleep 60
+#  perf script report flamegraph
+#
+# Combined data collection and flamegraph generation:
+#
+#  perf script flamegraph -a -F 99 sleep 60
+#
+# Written by Andreas Gerstmayr <agerstmayr@xxxxxxxxxx>
+# Flame Graphs invented by Brendan Gregg <bgregg@xxxxxxxxxxx>
+# Works in tandem with d3-flame-graph by Martin Spier <mspier@xxxxxxxxxxx>
+
+import sys
+import os
+import argparse
+import json
+
+
+class Node:
+    def __init__(self, name, libtype=""):
+        self.name = name
+        self.libtype = libtype
+        self.value = 0
+        self.children = []
+
+
+class FlameGraphCLI:
+    def __init__(self, args):
+        self.args = args
+        self.stack = Node("root")
+
+        if self.args.format == "html" and \
+                not os.path.isfile(self.args.template):
+            print(f"Flame Graph template '{self.args.template}' does not " +
+                  f"exist. Please install the d3-flame-graph package, " +
+                  f"specify an existing flame graph template " +
+                  f"(--template PATH) or another output format " +
+                  f"(--format FORMAT).", file=sys.stderr)
+            sys.exit(1)
+
+    def find_or_create_node(self, node, name, dso):
+        libtype = "kernel" if dso == "[kernel.kallsyms]" else ""
+        if name is None:
+            name = "[unknown]"
+
+        for child in node.children:
+            if child.name == name and child.libtype == libtype:
+                return child
+
+        child = Node(name, libtype)
+        node.children.append(child)
+        return child
+
+    def process_event(self, event):
+        node = self.find_or_create_node(self.stack, event["comm"], None)
+        if "callchain" in event:
+            for entry in reversed(event['callchain']):
+                node = self.find_or_create_node(
+                    node, entry.get("sym", {}).get("name"), event.get("dso"))
+        else:
+            node = self.find_or_create_node(
+                node, entry.get("symbol"), event.get("dso"))
+        node.value += 1
+
+    def trace_end(self):
+        def encoder(x): return x.__dict__
+        json_str = json.dumps(self.stack, default=encoder,
+                              indent=self.args.indent)
+
+        if self.args.format == "html":
+            try:
+                with open(self.args.template) as f:
+                    output_str = f.read().replace("/** @flamegraph_params **/",
+                                                  json_str)
+            except IOError as e:
+                print(f"Error reading template file: {e}", file=sys.stderr)
+                sys.exit(1)
+            output_fn = self.args.output or "flamegraph.html"
+        else:
+            output_str = json_str
+            output_fn = self.args.output or "stacks.json"
+
+        if output_fn == "-":
+            sys.stdout.write(output_str)
+        else:
+            try:
+                with open(output_fn, "w") as out:
+                    out.write(output_str)
+            except IOError as e:
+                print(f"Error writing output file: {e}", file=sys.stderr)
+                sys.exit(1)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Create flame graphs.")
+    parser.add_argument("-F", "--format",
+                        default="html", choices=["json", "html"],
+                        help="output file format")
+    parser.add_argument("-o", "--output",
+                        help="output file name")
+    parser.add_argument("--indent",
+                        type=int, help="JSON indentation")
+    parser.add_argument("--template",
+                        default="/usr/share/d3-flame-graph/template.html",
+                        help="path to flamegraph HTML template")
+    parser.add_argument("-i", "--input",
+                        help=argparse.SUPPRESS)
+
+    args = parser.parse_args()
+    cli = FlameGraphCLI(args)
+
+    process_event = cli.process_event
+    trace_end = cli.trace_end
-- 
2.24.1