From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D8CFE3C1085; Wed, 24 Jun 2026 14:20:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782310828; cv=none; b=bCDK6PcDMJ/xTqaAFJdQI2Ip0R+zYuQWj5bwmY6LXGBfMKWD4RVob77NT3UlRBLE2vnDDr4b3KKYJAciXpqkUUCk9E/6XcnI7DzdpOYEVicnJDiTKpDpa/m9L6zq0rcY4xlf8A06Z04SIip1bAIBpQYLCnKXCPjStcflAmRvkOc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782310828; c=relaxed/simple; bh=nubvS2VDtVju1y6WYgkOejoitMWvC9O6QM8HO1reoRM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RliDLRbVJzMg30eHsHTTKlLJ5F6I/JgyW1ItD1rihDD2vF07+KXji3iwIah+niODGXvAhgQfc2lX/AL4sSSg1vhnfxAdmJeQ6hnuEPDolxIck/8JCUUeLwymYeadKMvbg55b0o5WDl+nJNMcYiQh11Yi8qpaPp3iK2yQopHtqYM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BnR1B/g5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BnR1B/g5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 980811F000E9; Wed, 24 Jun 2026 14:20:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782310827; bh=r93tCIhwYTvoKawcFrjLmwPxR1Kntzh6Ey6FCsL943Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BnR1B/g5Cfc26bM4njpw6UNzV5hrILh0j3rSX4S5TxEZXDgF9eDpYuYgp0xhpP+ML BccNFa88UwLxfcwR+7nmpH/M9ps0xVmIdaHpmA669+MgSKd+T7045ZgZkcCph/0i5f cDtkicGsbJvpSaoXJgGuI2Pami+EwLYDCJ0ZvSsFii8yuLjGImZSfyw97helfbsPap URtFInac9pI6r8rh74DyKoaycBDEWrYN4ipzRFOv3KfN+PWZz84WYfMczIMQ62d23L 3BNtjFGjAVrLrE5akn3X9RWD8pDfMWstXva23vOCfbPS2d0QeCbAXZrdveib6Q86V8 iuJOmEjAzQ6TQ== From: SeongJae Park To: Cc: SeongJae Park , Andrew Morton , Brendan Higgins , David Gow , damon@lists.linux.dev, kunit-dev@googlegroups.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 03/11] mm/damon/tests/core-kunit: test damon_rand() Date: Wed, 24 Jun 2026 07:19:59 -0700 Message-ID: <20260624142008.87180-4-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260624142008.87180-1-sj@kernel.org> References: <20260624142008.87180-1-sj@kernel.org> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Commit 9012c4e647df ("mm/damon: replace damon_rand() with a per-ctx lockless PRNG") optimized DAMON for better performance. Add a kunit test for ensuring the pseudo randomness quality. Signed-off-by: SeongJae Park --- mm/damon/tests/core-kunit.h | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h index df16cc070eeb0..a1ba807d59a13 100644 --- a/mm/damon/tests/core-kunit.h +++ b/mm/damon/tests/core-kunit.h @@ -1488,6 +1488,26 @@ static void damon_test_walk_control_obsolete(struct kunit *test) damon_destroy_ctx(ctx); } +static void damon_test_rand(struct kunit *test) +{ + struct damon_ctx ctx; + int counts[10] = {}; + int i; + + prandom_seed_state(&ctx.rnd_state, get_random_u64()); + for (i = 0; i < 10000; i++) { + unsigned long rnd = damon_rand(&ctx, 0, 10); + + KUNIT_EXPECT_GE(test, rnd, 0); + KUNIT_EXPECT_LE(test, rnd, 9); + counts[rnd]++; + } + for (i = 0; i < 10; i++) { + KUNIT_EXPECT_GE(test, counts[i], 900); + KUNIT_EXPECT_LE(test, counts[i], 1100); + } +} + static struct kunit_case damon_test_cases[] = { KUNIT_CASE(damon_test_target), KUNIT_CASE(damon_test_regions), @@ -1518,6 +1538,7 @@ static struct kunit_case damon_test_cases[] = { KUNIT_CASE(damon_test_apply_min_nr_regions), KUNIT_CASE(damon_test_is_last_region), KUNIT_CASE(damon_test_walk_control_obsolete), + KUNIT_CASE(damon_test_rand), {}, }; -- 2.47.3