linux/tools/perf/python/perf_live.py
Ian Rogers ca23ecf8ee perf python: Allow KeyboardInterrupt to propagate in LiveSession
LiveSession.run() synchronously blocks while polling evlist for events.
When running interactive tools or scripts from the terminal,
KeyboardInterrupt exceptions raised via Ctrl-C must propagate so the
caller can break out of the polling loop.

Previously, LiveSession caught KeyboardInterrupt with an empty pass
statement, swallowing the exception and preventing calling scripts from
detecting the interrupt cleanly. Remove the empty handler so calling
scripts receive KeyboardInterrupt and can perform clean teardown.

Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2026-09-26 20:49:27 +02:00

64 lines
2.4 KiB
Python
Executable File

# 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)
self.evlist.config()
def run(self):
"""Run the live session."""
try:
self.evlist.open()
self.evlist.mmap()
self.evlist.enable()
while True:
# Poll for events with 100ms timeout
try:
self.evlist.poll(100)
# CPython's PyErr_SetFromErrno() invokes PyErr_CheckSignals() on
# EINTR, converting SIGINT into KeyboardInterrupt, which inherits
# from BaseException rather than InterruptedError/OSError, so
# Ctrl-C exits the loop and triggers finally: self.evlist.close()
# while non-fatal signals retry poll().
except InterruptedError:
continue
for cpu in self.cpus:
# Limit to 1000 events per CPU per poll to prevent starvation
for _ in range(1000):
try:
event = self.evlist.read_on_cpu(cpu)
except TypeError as e:
if "Unknown CPU" in str(e):
# CPU might be unmapped or offline, wait for mmap event
break
if "Unexpected header type" in str(e):
# Ignore valid but unsupported event types
continue
raise
if event is None:
break
if event.type == perf.RECORD_SAMPLE:
self.sample_callback(event)
finally:
self.evlist.close()