#!/usr/bin/env python3# SPDX-License-Identifier: GPL-2.0 import osimport subprocessimport 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()