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 C58A923B63E for ; Tue, 9 Jun 2026 13:25:01 +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=1781011502; cv=none; b=SGb/m4BP7ipEb7suWFjhb5cEkZV0QV5qF7Dk44C8L1sz19EdXaZ/hei0r1Ls1yx/kbgrx9kHJr9+EGVTqp9M28Y2uXcGSFevW8Tl79fm59JR9Ej3fb5TwQk4lX4JlXFGI7/tXsq2M+kNPNmITjbl2gZpQvJ0Iy9B2NNUHWyLl7Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781011502; c=relaxed/simple; bh=OhfdxOTXC2MrGMf0prBGNqS+h6zlx0l3W7HofyinHio=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WWKcsuDTYc6DnfILA21/5zUE9as44qrWBL7KAW8D7We6ubbcdsNbVSCpMsHXcmoQtRts3rnFaO1VEcy5Tu9F6/GgaQ5E90RQFpdNCg84wskSYmfdNGSX2asnO9NdFgK2GQlZ/77rRdd2q+G67WPuFH7jN+SDK3oUfTSgxAetw9U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=eT0iyD16; 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="eT0iyD16" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6EEC1F00893; Tue, 9 Jun 2026 13:24:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781011501; bh=vGB+OvVONd6SPuLHVWBqT8ifMP+j15JEDdf0lNucBcU=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=eT0iyD16ladRfod6LkrmqNSXjn+wr2cS9lONFb3qeVpeylpD5+UvMG1wFSCfd6Hpz E1A38VRANXVUkbCc6JzSpU2qhqakL3PzaX48DfXQvLN4urFNqNdQRMIeNbylc0QyNs Eiz3UD5phgEJwg4SgaTikP/DvTZPc+ZSMc5Br2T200YvKu4rHZQWxW7zd/56bzrZhl l23QPapzDpZErk9jNVC/QBau+Yrg8V1PeFHMpASLqxViqQtd43TPdlFrcr443U/bB3 s19BwDhfbwFSd5txhCy3AZcfW1oIZUb90VZqiI6lRFOxErW7dj4eZhp6abET4LRMcm WDGJSXVv3ZSmQ== Message-ID: <6dd97825-1da7-4de4-a508-41cb023e9803@kernel.org> Date: Tue, 9 Jun 2026 15:24:52 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 00/12] Optimize anonymous large folio unmapping To: Dev Jain , akpm@linux-foundation.org, ljs@kernel.org, chrisl@kernel.org, kasong@tencent.com, hughd@google.com, liam@infradead.org Cc: riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, baolin.wang@linux.alibaba.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260526063635.61721-1-dev.jain@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 On 5/26/26 08:36, Dev Jain wrote: > Speed up unmapping of anonymous large folios by clearing the ptes, and > setting swap ptes, in one go. > > The following benchmark (stolen from Barry at [1]) is used to measure the > time taken to swapout 256M worth of memory backed by 64K large folios: > > #define _GNU_SOURCE > #include > #include > #include > #include > #include > #include > #include > > #define SIZE_MB 256 > #define SIZE_BYTES (SIZE_MB * 1024 * 1024) > > int main() { > void *addr = mmap(NULL, SIZE_BYTES, PROT_READ | PROT_WRITE, > MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); > if (addr == MAP_FAILED) { > perror("mmap failed"); > return 1; > } > > memset(addr, 0, SIZE_BYTES); > > struct timespec start, end; > clock_gettime(CLOCK_MONOTONIC, &start); > > if (madvise(addr, SIZE_BYTES, MADV_PAGEOUT) != 0) { > perror("madvise(MADV_PAGEOUT) failed"); > munmap(addr, SIZE_BYTES); > return 1; > } > > clock_gettime(CLOCK_MONOTONIC, &end); > > long duration_ns = (end.tv_sec - start.tv_sec) * 1e9 + > (end.tv_nsec - start.tv_nsec); > printf("madvise(MADV_PAGEOUT) took %ld ns (%.3f ms)\n", > duration_ns, duration_ns / 1e6); > > munmap(addr, SIZE_BYTES); > return 0; > } > > Performance as measured on a Linux VM on Apple M3 (arm64): > > Vanilla - Mean: 37401913 ns, std dev: 12% > Patched - Mean: 17420282 ns, std dev: 11% -53% > > No regression observed on 4K folios. > > Performance as measured on bare metal x86: > > Vanilla - mean: 54986286 ns, std dev: 1.5% > Patched - mean: 51930795 ns, std dev: 3% That's still -5.5% (with a stddev of 3%). What happens on larger folio sizes? (e.g., 1 MiB) -- Cheers, David