linux-kernel - [PATCH 2/2] Add -e option to focus on the specific event for generating the flamegraph

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Message-ID: <20250610040536.2390060-2-tianyou.li@intel.com>
Date: Tue, 10 Jun 2025 12:04:23 +0800
From: Tianyou Li <tianyou.li@...el.com>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	tianyou.li@...el.com,
	wangyang.guo@...el.com,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] Add -e option to focus on the specific event for generating the flamegraph

When processing the perf data file generated with multiple events,
the flamegraph script will count all the events regardless of
different event names.

This patch tries to add a -e option to specify the event name that
the flamegraph will be generated accordingly. If the -e option omitted,
the behavior remains unchanged.

Signed-off-by: Tianyou Li <tianyou.li@...el.com>
Reviewed-by: Pan Deng <pan.deng@...el.com>
Reviewed-by: Zhiguo Zhou <zhiguo.zhou@...el.com>
Reviewed-by: Wangyang Guo <wangyang.guo@...el.com>
Reviewed-by: Tim Chen <tim.c.chen@...ux.intel.com>
---
 tools/perf/scripts/python/flamegraph.py | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/tools/perf/scripts/python/flamegraph.py b/tools/perf/scripts/python/flamegraph.py
index 4f82dfea0a70..e49ff242b779 100755
--- a/tools/perf/scripts/python/flamegraph.py
+++ b/tools/perf/scripts/python/flamegraph.py
@@ -94,6 +94,11 @@ class FlameGraphCLI:
         return child
 
     def process_event(self, event):
+        # ignore events where the event name does not match
+        # the one specified by the user
+        if self.args.event_name and event.get("ev_name") != self.args.event_name:
+            return
+
         pid = event.get("sample", {}).get("pid", 0)
         # event["dso"] sometimes contains /usr/lib/debug/lib/modules/*/vmlinux
         # for user-space processes; let's use pid for kernel or user-space distinction
@@ -130,7 +135,10 @@ class FlameGraphCLI:
             else:
                 output = subprocess.check_output(["perf", "report", "--header-only"])
 
-            return output.decode("utf-8")
+            result = output.decode("utf-8")
+            if self.args.event_name:
+                result += "\nFocused event: " + self.args.event_name
+            return result
         except Exception as err:  # pylint: disable=broad-except
             print("Error reading report header: {}".format(err), file=sys.stderr)
             return ""
@@ -241,6 +249,11 @@ if __name__ == "__main__":
                         default=False,
                         action="store_true",
                         help="allow unprompted downloading of HTML template")
+    parser.add_argument("-e", "--event",
+                        default="",
+                        dest="event_name",
+                        type=str,
+                        help="specify the event to generate flamegraph for")
 
     cli_args = parser.parse_args()
     cli = FlameGraphCLI(cli_args)
-- 
2.47.1