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Message-ID: <13a2ce75-b1c0-4930-8911-36ded0b428a7@redhat.com>
Date:   Mon, 27 Nov 2023 15:50:46 +0100
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Subject: Re: [RESEND PATCH v7 10/10] selftests/mm/cow: Add tests for anonymous
 small-sized THP
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To:     Ryan Roberts <ryan.roberts@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Yin Fengwei <fengwei.yin@intel.com>,
        Yu Zhao <yuzhao@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Yang Shi <shy828301@gmail.com>,
        "Huang, Ying" <ying.huang@intel.com>, Zi Yan <ziy@nvidia.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Itaru Kitayama <itaru.kitayama@gmail.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        John Hubbard <jhubbard@nvidia.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Hugh Dickins <hughd@google.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>
Cc:     linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org
References: <20231122162950.3854897-1-ryan.roberts@arm.com>
 <20231122162950.3854897-11-ryan.roberts@arm.com>
 <8dd0f52c-d261-4541-930f-bd4e5921be5b@arm.com>
From:   David Hildenbrand <david@redhat.com>
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In-Reply-To: <8dd0f52c-d261-4541-930f-bd4e5921be5b@arm.com>
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Precedence: bulk

On 27.11.23 15:02, Ryan Roberts wrote:
> On 22/11/2023 16:29, Ryan Roberts wrote:
>> Add tests similar to the existing PMD-sized THP tests, but which operate
>> on memory backed by (PTE-mapped) small-sized THP. This reuses all the
>> existing infrastructure. If the test suite detects that small-sized THP
>> is not supported by the kernel, the new tests are skipped.
>>
>> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
>> ---
>>   tools/testing/selftests/mm/cow.c | 71 +++++++++++++++++++++++++++++++-
>>   1 file changed, 70 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
>> index d03c453cfd5c..3efc395c7077 100644
>> --- a/tools/testing/selftests/mm/cow.c
>> +++ b/tools/testing/selftests/mm/cow.c
>> @@ -29,15 +29,49 @@
>>   #include "../../../../mm/gup_test.h"
>>   #include "../kselftest.h"
>>   #include "vm_util.h"
>> +#include "thp_settings.h"
>>
>>   static size_t pagesize;
>>   static int pagemap_fd;
>>   static size_t pmdsize;
>> +static int nr_thpsmallsizes;
>> +static size_t thpsmallsizes[20];
> 
> Off the back of some comments David made againt the previous patch [1], I'm
> proposing to rework this a bit so that ALL thp sizes are stored in this array,
> not just the non-PMD-sized sizes. This makes the changes overall a bit smaller
> and easier to understand, I think...
> 
>>   static int nr_hugetlbsizes;
>>   static size_t hugetlbsizes[10];
>>   static int gup_fd;
>>   static bool has_huge_zeropage;
>>
>> +static int sz2ord(size_t size)
>> +{
>> +	return __builtin_ctzll(size / pagesize);
>> +}
>> +
>> +static int detect_smallthp_sizes(size_t sizes[], int max)
> 
> This changes to detect_thp_sizes() and deposits all sizes in sizes[]

Just what I wanted to propose :) Makes it simpler by removing the 
"small" terminology and just detecting thp sizes.

-- 
Cheers,

David / dhildenb