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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766042563; bh=v8cAalRQn43JyXFhRWos5ZPdRsZtNdz6rnazo+rNvyE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=IiFtzWuMvKFyQXgkjfnEsQWHGnpImypXXT+oPLEYQCLJn/YvQN+eI2Et9GNHnUhN+ i+gH/qKbSbixNoOHsW9F5Blvg01u7KKsvOyMcGXMzwRFqll2KtwgTGESGuzyZ0Do7M wMjhcvVZYs9r0oLSt1MBDGJNHqzosSrkpCPqxi3hbL/QZ3WR73t4Git79o6y4o9Wac 3PzQS3ZWVuE/xF/nOchsxWXkJoPKH5QO/MC6JACnRIVKMk+PKgfgSj8YomHVYkPvW5 UyBHYf5hV7J5ZeaXVCAQp/+cSoZ51yDkubbrrIn0jKf44Bfp3CTBIZzlhRzMFEZ60B 2hCYXKZYq2Iog== Message-ID: Date: Thu, 18 Dec 2025 08:22:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 6/8] x86/clear_page: Introduce clear_pages() To: Ankur Arora , linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org Cc: akpm@linux-foundation.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, mjguzik@gmail.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, willy@infradead.org, raghavendra.kt@amd.com, chleroy@kernel.org, ioworker0@gmail.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com References: <20251215204922.475324-1-ankur.a.arora@oracle.com> <20251215204922.475324-7-ankur.a.arora@oracle.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: <20251215204922.475324-7-ankur.a.arora@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 45CD11C0002 X-Stat-Signature: fx9adu5rqtqa8r3hd8xarqh4yy6zeq73 X-Rspam-User: X-HE-Tag: 1766042565-576972 X-HE-Meta: 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 Oy63hKO/ tB3ej2V6Bt9GlhlA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 12/15/25 21:49, Ankur Arora wrote: > Performance when clearing with string instructions (x86-64-stosq and > similar) can vary significantly based on the chunk-size used. > > $ perf bench mem memset -k 4KB -s 4GB -f x86-64-stosq > # Running 'mem/memset' benchmark: > # function 'x86-64-stosq' (movsq-based memset() in arch/x86/lib/memset_64.S) > # Copying 4GB bytes ... > > 13.748208 GB/sec > > $ perf bench mem memset -k 2MB -s 4GB -f x86-64-stosq > # Running 'mem/memset' benchmark: > # function 'x86-64-stosq' (movsq-based memset() in > # arch/x86/lib/memset_64.S) > # Copying 4GB bytes ... > > 15.067900 GB/sec > > $ perf bench mem memset -k 1GB -s 4GB -f x86-64-stosq > # Running 'mem/memset' benchmark: > # function 'x86-64-stosq' (movsq-based memset() in arch/x86/lib/memset_64.S) > # Copying 4GB bytes ... > > 38.104311 GB/sec > > (Both on AMD Milan.) > > With a change in chunk-size from 4KB to 1GB, we see the performance go > from 13.7 GB/sec to 38.1 GB/sec. For the chunk-size of 2MB the change isn't > quite as drastic but it is worth adding a clear_page() variant that can > handle contiguous page-extents. > > Signed-off-by: Ankur Arora > Tested-by: Raghavendra K T Nothing jumped at me. Reviewed-by: David Hildenbrand (Red Hat) -- Cheers David