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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 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 X-Rspamd-Queue-Id: 4D8BB8000A X-Rspam-User: X-Stat-Signature: n7ekks4rmxwc4x3ed3ndi5k8dhpxq3er X-Rspamd-Server: rspam08 X-HE-Tag: 1781011502-30860 X-HE-Meta: U2FsdGVkX19uMwCMDcMS/c70i73QLfbweTFgeM0Ce6FX2Dv6gKlo+2oVNtadUa8ua962nr1KysrcyVdIslVAhf4mFsvHXAWm52oz6gXY31V74COqsg8GaEPduZzrecOPgONj6IYJiyS//mhCevWznczHYFcY9PwqjI5l4fVdJpfSerOBUtuQ8GxecOXuzMkJZAYnDigu2NlL0X2Ycnn4iFyebLx8ewiFdT5Des9RJHTzegZJnEa9AwDWnJDUadNyXZGwZFkInIupr9ehx7o3KmyjzSjYo/TIN86pZKY0Oi9nWM1bZIRBiJfp6WOQTX7a4r+R3YgGn1p8h3wJ4GawUFtmyotOgsSBQm6VBfOmVS2xQwI8uA5JzotIQjzbGFoU2zoTUiMmSmAIH2nCR+xIwFyyvNN4CgdiaBbbx0GXxcKSHL1l1wG9wvAS1Y3wzWIkFXuPVo+nBE5h3D/BdQSonXTgsQ/iO6AK2HuoLS3iDjogv3OlQrnyt2XqLFF+5S2Pmzh45zlyJ44OvpDdODi+mZH2opHOyM1G/a0FBkbCddJ5mrzBMwqZDgbXPxLlTHcW2taD/oay1uJDCNhYbu4GwiSkreZmU9TPa00LswOwenZJ0lze7Fg4HFDJtDwAZCJvAf8tL+RY+aFr/v6Q75HoyrP3rJUY9GYhS9nBzjXr1tUjJ2FgmT1tAirupKsthVbb6yyiRv+1hX6eQF7FwZUhcbN0FBitzH3HrzAy/IAkgfsyIQki1PyS8ISxSr736Ukxhp1yUH/WlNccyrh9Eu8K3h3BK54gcXL0ZEcwiAR0m7GwBWi+ohSQ+Ate5r6y/kHFRWiCpu4yfGCLH3FUp+WTYwDgP896AVRu1wVM+STQhvzNvZqlVxmJzpedTc+T9tUGKPsCDLo/ba4tqfDQdh3i9DVLHrigv9YIB7G1kx0LJs6woWN18IwewHDjRIR0xl6O+16mzN57KMyH/RQyH2B KP7H3jDu +GBjy3H80xzVxhAyCfLtPY/gEwqPB3T19Qc6oGiUaiywLzegcU3qKdxxAgf8oM/T+7GHiKiKxMdyfGHdP4XdiB7Xowa0hKY3th5p0cTqWkPGiSQGAOAzUpXbn1xZs2tnF1G3EU2Gw0AkVqTcbvo8U608X7EvKxJpPwCO7w0Ysv1lQlLWd9SWIYV4iqIr9kqWaPwf7047VPkUJ05QXmnr25zJA4lCnx+jZ+7OKHVkGdI77akjAyhPY4DeKPcmNDyRxx1fK Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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