Writing a non-zero value to a kdamond's 'refresh_ms' sysfs file should make DAMON periodically update the read-only sysfs files on its own, without the user writing update keywords such as 'update_schemes_stats' to the 'state' file. This behavior has no test coverage.
Add a test that starts a kdamond with refresh_ms set and a 'stat' scheme whose default access pattern matches every monitored region, then polls the scheme's 'nr_tried' stats file directly, without requesting an update. The value can become non-zero only via the periodic refresh, so the test confirms refresh_ms works; with refresh_ms disabled the stat stays zero and the test fails. Signed-off-by: Ruslan Valiyev <[email protected]> --- tools/testing/selftests/damon/Makefile | 1 + .../testing/selftests/damon/sysfs_refresh.py | 75 +++++++++++++++++++ 2 files changed, 76 insertions(+) create mode 100755 tools/testing/selftests/damon/sysfs_refresh.py diff --git a/tools/testing/selftests/damon/Makefile b/tools/testing/selftests/damon/Makefile index 2180c328a8252..ece244e5c5b95 100644 --- a/tools/testing/selftests/damon/Makefile +++ b/tools/testing/selftests/damon/Makefile @@ -13,6 +13,7 @@ TEST_PROGS += sysfs.py TEST_PROGS += sysfs_update_schemes_tried_regions_wss_estimation.py TEST_PROGS += damos_quota.py damos_quota_goal.py damos_apply_interval.py TEST_PROGS += damos_tried_regions.py damon_nr_regions.py +TEST_PROGS += sysfs_refresh.py TEST_PROGS += reclaim.sh lru_sort.sh # regression tests (reproducers of previously found bugs) diff --git a/tools/testing/selftests/damon/sysfs_refresh.py b/tools/testing/selftests/damon/sysfs_refresh.py new file mode 100755 index 0000000000000..012b7e8f509f5 --- /dev/null +++ b/tools/testing/selftests/damon/sysfs_refresh.py @@ -0,0 +1,75 @@ +#!/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() -- 2.43.0
