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#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0
import os
import subprocess
import time
import _damon_sysfs
def main():
# Continuously access a memory region for far longer than the test needs,
# so the kdamond always has a live target to monitor while we poll.
sz_region = 10 * 1024 * 1024
proc = subprocess.Popen(
['./access_memory', '1', '%d' % sz_region, '60000', 'repeat'])
# A 'stat' scheme with the default (maximally wide) access pattern matches
# every monitored region, so its 'nr_tried' stat increases as the kdamond
# runs. refresh_ms should make DAMON update the schemes' stats files under
# sysfs on its own, without a manual 'update_schemes_stats' request.
kdamond = _damon_sysfs.Kdamond(
refresh_ms=100,
contexts=[_damon_sysfs.DamonCtx(
ops='vaddr',
targets=[_damon_sysfs.DamonTarget(pid=proc.pid)],
schemes=[_damon_sysfs.Damos(action='stat')],
)])
kdamonds = _damon_sysfs.Kdamonds([kdamond])
err = kdamonds.start()
if err is not None:
# Kernels older than the refresh_ms feature have no such file; treat
# that as unsupported rather than a failure.
if not os.path.exists(os.path.join(kdamond.sysfs_dir(), 'refresh_ms')):
proc.terminate()
proc.wait()
print('kdamond has no refresh_ms file; skipping')
exit(_damon_sysfs.ksft_skip)
proc.terminate()
proc.wait()
print('kdamond start failed: %s' % err)
exit(1)
scheme = kdamond.contexts[0].schemes[0]
nr_tried_path = os.path.join(scheme.sysfs_dir(), 'stats', 'nr_tried')
try:
# Poll the stat file directly. We never request an update (e.g.
# 'update_schemes_stats'), so 'nr_tried' can become non-zero only
# through the periodic refresh that refresh_ms enables.
nr_tried = 0
deadline = time.monotonic() + 10
while time.monotonic() < deadline:
if proc.poll() is not None:
print('the access_memory target exited unexpectedly')
exit(1)
content, err = _damon_sysfs.read_file(nr_tried_path)
if err is not None:
print('reading %s failed: %s' % (nr_tried_path, err))
exit(1)
nr_tried = int(content)
if nr_tried > 0:
break
time.sleep(0.1)
finally:
kdamonds.stop()
proc.terminate()
proc.wait()
if nr_tried == 0:
print('refresh_ms did not auto-update the schemes stats')
exit(1)
if __name__ == '__main__':
main()
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