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a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788791826; b=03NjyXakM9qdjTAYBgPEwnpgWCTfhyqy2fLRJw+VVbLLXmlQkQQJZ9jG75gdoWtBy4uERC 9RSjA/815JsO/jmWdYj2z/LfC6gpeEQzwxLrcvom9cxu54aIJL6tLuVQrlaNIAYtztRlmf i+gUoyQ8eyk2RRCO6mUb0lsC5LSp4KU= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=fTsNlF5q; spf=pass (imf13.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 130204096B; Mon, 7 Sep 2026 14:37:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 549C31F00A3A; Mon, 7 Sep 2026 14:36:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788791825; bh=2dFmlZ2YhxBRrcc8f1XDZg+4p46ZaRA0KsVdhSI9A9k=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=fTsNlF5qXOl6OwLzVuaYAniAR1fo5SJUeWa258aoCLLwCtAxXx0zHhJrF+sdx5vbr 3lb6+wyYVfJla+j56FQlmO+yri3oZ6+g830MUEIIS7ls7FwUrOz6lOxWkWcfHyt6rA nyUwdgZ04ERH/PzzM+KmyGNyIImfaehdWYeK/64TUxEREtcIS6tu9TTSsGQykTlmds +LJRSfKWdd6sMCBuOoQsdZl/Kj1thDoVh56ySlrNbqlV1dvXS5LLpUgABJSpCCb/0M KtwtfZ/eLkr1fLnDerSvqAw7CTotyxD8LoL/qgnW4HTIb1qww/oRNlZuVfN6DTTcsf DbuCuh8Lmjg1g== Message-ID: <9f8c6e91-c1c8-4ec5-96a9-9d6d4ab571cc@kernel.org> Date: Mon, 7 Sep 2026 16:36:56 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] kselftest: mm: remove HPAGE_SIZE and HPAGE_SHIFT macro To: Yeoreum Yun , linux-mm@kvack.org, linux-kselftest@vger.kernel.org Cc: akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, kas@kernel.org, sarthak.sharma@arm.com References: <20260907081509.924979-1-yeoreum.yun@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: E180520003 X-Stat-Signature: hn5gehc5sb8xdfw9zppgt3753gdkrh4f X-HE-Tag: 1788791825-935965 X-HE-Meta: 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 jJ46TfzJ OqaA7e28wJ7+0WLfRBAsUBP5vT7moW0GinzRROfR24y7rrjiVVLyTWJNzgTjUpAFd9ryB5l3/arx8ZYOC1NuQbJN2WiZfI4zMc5WGJ1/hscq6XA637TF5MXBa7JpD8ndpaAyDyT8WEkLnm4eSZwjC+TM1Z287ASa93q5fASnBxiihJxxxBskKZaezoDVgwFApKXW1s69t2d86yRwfbXi7h4BOF1fptuMeqA6NQ4nbmfMTpx9ZTz1LKCnfK/MZr8cp7uDgdypvlKvyk3xTVRQRaWkJYlFXMAdNyvqmNMiIAAuNXbVs3BTysnbEwHbRL+Xdx1Ui+edGG3eDX3z1s2K9rG7v5aN7Q/yst+WtPn1A2uLxQhhC24t0PVe/o5vBlkuK/GWyzG/kG+zFbpU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/7/26 10:15, Yeoreum Yun wrote: > HPAGE_SIZE and HPAGE_SHIFT macro is written based on the 4KB PAGE_SIZE. > When this macro is used in some test, test result would be strange in > the system where PAGE_SIZE is more then 4KB. > > Here is the example with transhuge-stress test with 16KB PAGE_SIZE: > > transhuge-stress: allocate 61073 transhuge pages, using 122146 MiB virtual memory and 1908 MiB of ram > 3.292 s/loop, 0.054 ms/page, 37106.002 MiB/s 2566 succeed, 58507 failed, 2566 different pages > 0.591 s/loop, 0.010 ms/page, 206850.792 MiB/s 0 succeed, 61073 failed, 0 different pages > 0.527 s/loop, 0.009 ms/page, 231895.107 MiB/s 0 succeed, 61073 failed, 0 different pages > 0.527 s/loop, 0.009 ms/page, 231839.704 MiB/s 0 succeed, 61073 failed, 0 different pages > 0.528 s/loop, 0.009 ms/page, 231544.782 MiB/s 0 succeed, 61073 failed, 0 different pages > 0.528 s/loop, 0.009 ms/page, 231462.074 MiB/s 0 succeed, 61073 failed, 0 different pages > 0.527 s/loop, 0.009 ms/page, 231770.300 MiB/s 0 succeed, 61073 failed, 0 different pages > ... > ok 1 Completed > > Remove the HPAGE_SIZE and HPAGE_SHIFT macros and introduce pmd_page_shift() > helper to get the HPAGE_SHIFT properly. For HPAGE_SIZE, use pre-existing > helper, read_pmd_pagesize(). > > Also, run the KSM_MERGE_TIME_HUGE_PAGES test with a size of 512 MiB, > which is the least common multiple of the PMD sizes for 4 KiB, 16 KiB, > and 64 KiB base pages. Since allocate_transhuge() allocates mappings in > PMD-sized units, the test may fail with the previous size of 100 MiB, > which is not a multiple of the PMD size when the base page size is > 16 KiB or 64 KiB. > > After this patch, output of transhuge-stress: > > transhuge-stress: allocate 3817 transhuge pages, using 122146 MiB virtual memory and 119 MiB of ram > 2.558 s/loop, 0.670 ms/page, 47755.759 MiB/s 2585 succeed, 1232 failed, 2585 different pages > 2.640 s/loop, 0.692 ms/page, 46268.432 MiB/s 2585 succeed, 1232 failed, 2585 different pages > 2.635 s/loop, 0.690 ms/page, 46360.298 MiB/s 2585 succeed, 1232 failed, 2585 different pages > 2.782 s/loop, 0.729 ms/page, 43899.795 MiB/s 2616 succeed, 1201 failed, 2616 different pages > 2.692 s/loop, 0.705 ms/page, 45380.876 MiB/s 2627 succeed, 1190 failed, 2627 different pages > 2.612 s/loop, 0.684 ms/page, 46765.812 MiB/s 2628 succeed, 1189 failed, 2628 different pages > 2.683 s/loop, 0.703 ms/page, 45520.990 MiB/s 2630 succeed, 1187 failed, 2630 different pages > 2.727 s/loop, 0.714 ms/page, 44789.321 MiB/s 2631 succeed, 1186 failed, 2631 different pages > ... > ok 1 Completed > > Suggested-by: Lorenzo Stoakes (ARM) > Signed-off-by: Yeoreum Yun > --- [...] > diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh > index d09f9f6a384e..24aa1de27c25 100755 > --- a/tools/testing/selftests/mm/run_vmtests.sh > +++ b/tools/testing/selftests/mm/run_vmtests.sh > @@ -360,8 +360,8 @@ fi > CATEGORY="memfd_secret" run_test ./memfd_secret > fi > > -# KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 100 > -CATEGORY="ksm" run_test ./ksm_tests -H -s 100 > +# KSM KSM_MERGE_TIME_HUGE_PAGES test with size of 512 > +CATEGORY="ksm" run_test ./ksm_tests -H -s 512 Why the magic value 512? (desrves a comment) A clear sign that the ksm tests must be rewritten to be standalone and just handle this internally. @Sarthak > # KSM KSM_MERGE_TIME test with size of 100 > CATEGORY="ksm" run_test ./ksm_tests -P -s 100 > # KSM MADV_MERGEABLE test with 10 identical pages [...] > index 4821a3563036..f75bf0bacd18 100644 > --- a/tools/testing/selftests/mm/vm_util.c > +++ b/tools/testing/selftests/mm/vm_util.c > @@ -21,6 +21,8 @@ > > unsigned int __page_size; > unsigned int __page_shift; > +uint64_t __pmd_page_size; > +uint64_t __pmd_page_shift; > > uint64_t pagemap_get_entry(int fd, char *start) > { > @@ -161,6 +163,9 @@ uint64_t read_pmd_pagesize(void) > char buf[20]; > ssize_t num_read; > > + if (__pmd_page_size) > + return __pmd_page_size; > + > fd = open(PMD_SIZE_FILE_PATH, O_RDONLY); > if (fd == -1) > return 0; > @@ -173,7 +178,25 @@ uint64_t read_pmd_pagesize(void) > buf[num_read] = '\0'; > close(fd); > > - return strtoul(buf, NULL, 10); > + __pmd_page_size = strtoul(buf, NULL, 10); > + > + return __pmd_page_size; > +} > + > +uint64_t pmd_page_shift(void) > +{ > + if (__pmd_page_shift) > + return __pmd_page_shift; > + > + if (!__pmd_page_size) > + __pmd_page_size = read_pmd_pagesize(); > + > + if (!__pmd_page_size) > + return 0; > + > + __pmd_page_shift = (ffsl(__pmd_page_size) - 1); > + > + return __pmd_page_shift; > } The interface is a bit inconsistent. read_pmd_pagesize() vs. pmd_page_shift(). Consider renaming read_pmd_pagesize() to pmd_pagesize() in a cleanup patch. ... or (better?) adding a size_to_shift() helper instead? I think most places that want the shift also want the size. So this can just be const uint64_t hpage_size = read_pmd_pagesize(); const uint64_t hpage_shift = size_to_shift(hpage_size); In size_to_shift(), you can just handle if (size == 0) return 0; etc. -- Cheers, David