[PATCH v1 23/58] perf python: Add LiveSession helper

[Ian Rogers]

Add LiveSession class in tools/perf/python/perf_live.py to support
live event collection using perf.evlist and perf.parse_events,
avoiding the need to fork a separate perf record process.

Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
Assisted-by: Gemini:gemini-3.1-pro-preview
---
 tools/perf/python/perf_live.py | 42 ++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100755 tools/perf/python/perf_live.py

diff --git a/tools/perf/python/perf_live.py b/tools/perf/python/perf_live.py
new file mode 100755
index 000000000000..81d92f720b58
--- /dev/null
+++ b/tools/perf/python/perf_live.py
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: GPL-2.0
+"""
+Live event session helper using perf.evlist.
+
+This module provides a LiveSession class that allows running a callback
+for each event collected live from the system, similar to perf.session
+but without requiring a perf.data file.
+"""
+
+import perf
+
+
+class LiveSession:
+    """Represents a live event collection session."""
+
+    def __init__(self, event_string: str, sample_callback):
+        self.event_string = event_string
+        self.sample_callback = sample_callback
+        # Create a cpu map for all online CPUs
+        self.cpus = perf.cpu_map()
+        # Parse events and set maps
+        self.evlist = perf.parse_events(self.event_string, self.cpus)
+
+    def run(self):
+        """Run the live session."""
+        self.evlist.open()
+        self.evlist.mmap()
+
+        try:
+            while True:
+                # Poll for events with 100ms timeout
+                self.evlist.poll(100)
+                for cpu in self.cpus:
+                    event = self.evlist.read_on_cpu(cpu)
+                    while event:
+                        if event.type == perf.RECORD_SAMPLE:
+                            self.sample_callback(event)
+                        event = self.evlist.read_on_cpu(cpu)
+        except KeyboardInterrupt:
+            pass
+        finally:
+            self.evlist.close()
-- 
2.54.0.rc1.513.gad8abe7a5a-goog