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Tue, 02 Jun 2026 06:12:19 -0700 (PDT) From: Ruslan Valiyev To: SeongJae Park Cc: Shuah Khan , damon@lists.linux.dev, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linuxoid@gmail.com Subject: [PATCH 1/2] selftests/damon/_damon_sysfs: support kdamond refresh_ms Date: Tue, 2 Jun 2026 15:12:16 +0200 Message-ID: <20260602131217.2210912-2-linuxoid@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260602131217.2210912-1-linuxoid@gmail.com> References: <20260602131217.2210912-1-linuxoid@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The Kdamond class has no way to set the kdamond-level 'refresh_ms' sysfs file, which makes DAMON periodically update the read-only sysfs files (DAMOS stats, tuned monitoring intervals and the kdamond pid) on its own. Add a 'refresh_ms' parameter to Kdamond. When it is set (including to zero, to disable the periodic update), write it before turning the kdamond on, so tests can exercise the auto-update behavior. Leaving it unset keeps the previous behavior of not touching the file, so callers running against kernels without the feature are unaffected. Signed-off-by: Ruslan Valiyev Reviewed-by: SeongJae Park --- tools/testing/selftests/damon/_damon_sysfs.py | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/damon/_damon_sysfs.py b/tools/testing/= selftests/damon/_damon_sysfs.py index 2b4df655d9fd0..1a498c78a4149 100644 --- a/tools/testing/selftests/damon/_damon_sysfs.py +++ b/tools/testing/selftests/damon/_damon_sysfs.py @@ -667,12 +667,14 @@ class DamonCtx: class Kdamond: state =3D None pid =3D None + refresh_ms =3D None contexts =3D None idx =3D None # index of this kdamond between siblings kdamonds =3D None # parent =20 - def __init__(self, contexts=3D[]): + def __init__(self, contexts=3D[], refresh_ms=3DNone): self.contexts =3D contexts + self.refresh_ms =3D refresh_ms for idx, context in enumerate(self.contexts): context.idx =3D idx context.kdamond =3D self @@ -695,6 +697,11 @@ class Kdamond: err =3D context.stage() if err is not None: return err + if self.refresh_ms is not None: + err =3D write_file(os.path.join(self.sysfs_dir(), 'refresh_ms'= ), + '%d' % self.refresh_ms) + if err is not None: + return err err =3D write_file(os.path.join(self.sysfs_dir(), 'state'), 'on') if err is not None: return err --=20 2.43.0 From nobody Mon Jun 8 04:11:44 2026 Received: from mail-wm1-f45.google.com (mail-wm1-f45.google.com [209.85.128.45]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A3F8F3DB334 for ; 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Tue, 02 Jun 2026 06:12:20 -0700 (PDT) Received: from x1.tail0e71db.ts.net ([46.140.7.198]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45ef34c3081sm33234665f8f.15.2026.06.02.06.12.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Jun 2026 06:12:20 -0700 (PDT) From: Ruslan Valiyev To: SeongJae Park Cc: Shuah Khan , damon@lists.linux.dev, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linuxoid@gmail.com Subject: [PATCH 2/2] selftests/damon/sysfs_refresh: test kdamond refresh_ms Date: Tue, 2 Jun 2026 15:12:17 +0200 Message-ID: <20260602131217.2210912-3-linuxoid@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260602131217.2210912-1-linuxoid@gmail.com> References: <20260602131217.2210912-1-linuxoid@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: SeongJae Park --- 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/selftes= ts/damon/Makefile index 2180c328a8252..ece244e5c5b95 100644 --- a/tools/testing/selftests/damon/Makefile +++ b/tools/testing/selftests/damon/Makefile @@ -13,6 +13,7 @@ TEST_PROGS +=3D sysfs.py TEST_PROGS +=3D sysfs_update_schemes_tried_regions_wss_estimation.py TEST_PROGS +=3D damos_quota.py damos_quota_goal.py damos_apply_interval.py TEST_PROGS +=3D damos_tried_regions.py damon_nr_regions.py +TEST_PROGS +=3D sysfs_refresh.py TEST_PROGS +=3D reclaim.sh lru_sort.sh =20 # 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 nee= ds, + # so the kdamond always has a live target to monitor while we poll. + sz_region =3D 10 * 1024 * 1024 + proc =3D subprocess.Popen( + ['./access_memory', '1', '%d' % sz_region, '60000', 'repeat']) + + # A 'stat' scheme with the default (maximally wide) access pattern mat= ches + # every monitored region, so its 'nr_tried' stat increases as the kdam= ond + # runs. refresh_ms should make DAMON update the schemes' stats files = under + # sysfs on its own, without a manual 'update_schemes_stats' request. + kdamond =3D _damon_sysfs.Kdamond( + refresh_ms=3D100, + contexts=3D[_damon_sysfs.DamonCtx( + ops=3D'vaddr', + targets=3D[_damon_sysfs.DamonTarget(pid=3Dproc.pid)], + schemes=3D[_damon_sysfs.Damos(action=3D'stat')], + )]) + kdamonds =3D _damon_sysfs.Kdamonds([kdamond]) + + err =3D kdamonds.start() + if err is not None: + # Kernels older than the refresh_ms feature have no such file; tre= at + # that as unsupported rather than a failure. + if not os.path.exists(os.path.join(kdamond.sysfs_dir(), 'refresh_m= s')): + 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 =3D kdamond.contexts[0].schemes[0] + nr_tried_path =3D 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 =3D 0 + deadline =3D time.monotonic() + 10 + while time.monotonic() < deadline: + if proc.poll() is not None: + print('the access_memory target exited unexpectedly') + exit(1) + content, err =3D _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 =3D int(content) + if nr_tried > 0: + break + time.sleep(0.1) + finally: + kdamonds.stop() + proc.terminate() + proc.wait() + + if nr_tried =3D=3D 0: + print('refresh_ms did not auto-update the schemes stats') + exit(1) + +if __name__ =3D=3D '__main__': + main() --=20 2.43.0