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imf06.hostedemail.com; dkim=none; spf=pass (imf06.hostedemail.com: domain of dev.jain@arm.com designates 217.140.110.172 as permitted sender) smtp.mailfrom=dev.jain@arm.com; dmarc=pass (policy=none) header.from=arm.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1773134939; a=rsa-sha256; cv=none; b=RhpKwVtbdyf9qgM0k5EcU8e48kvVRiQOMXSoE67QPaPyrv/0jxwm+ZF6bbzmGrNp7FPAw3 bGxohpDlkDW9gpc3af3MkKzv2glBuAY7SGSVJNgw06P7X0x+rAjP/lvrFJ/8vvxEZN15Ss HukuujoxzOCHYqaFq7HUXsYj0HDqP0Q= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0A31F16A3; Tue, 10 Mar 2026 02:28:52 -0700 (PDT) Received: from [10.164.19.59] (unknown [10.164.19.59]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6ED8A3F73B; Tue, 10 Mar 2026 02:28:50 -0700 (PDT) Message-ID: <0a5279ba-7964-49ea-a84b-c80b5e53c359@arm.com> Date: Tue, 10 Mar 2026 14:58:47 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/9] mm/rmap: Optimize anonymous large folio unmapping To: "Lorenzo Stoakes (Oracle)" Cc: akpm@linux-foundation.org, axelrasmussen@google.com, yuanchu@google.com, david@kernel.org, hughd@google.com, chrisl@kernel.org, kasong@tencent.com, weixugc@google.com, Liam.Howlett@oracle.com, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, riel@surriel.com, harry.yoo@oracle.com, jannh@google.com, pfalcato@suse.de, baolin.wang@linux.alibaba.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, baohua@kernel.org, youngjun.park@lge.com, ziy@nvidia.com, kas@kernel.org, willy@infradead.org, yuzhao@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260310073013.4069309-1-dev.jain@arm.com> <032ab9a6-a49f-41c7-81fe-1c6fbaf94a79@lucifer.local> Content-Language: en-US From: Dev Jain In-Reply-To: <032ab9a6-a49f-41c7-81fe-1c6fbaf94a79@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 1CA20180009 X-Rspamd-Server: rspam07 X-Stat-Signature: jy54ecio853cqp196dnnf69d9g11fmcu X-Rspam-User: X-HE-Tag: 1773134938-585725 X-HE-Meta: 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 aQKyHahl tuQKOuq5piyzgZ4iksHaqyMIljOdjCaD0M2whZDFpthKlib+6Rge/aNeO2akC11KZDAV0vWL/S/WP53aZnYOMzy4ustBqR4VpjGIQBj6k7mSeW2dHK14Az5rv79vW5aJlYXUmCYCR9nR90RGJ6xucIz3zrX29m/KclAZ72HlODlbJxOm6dyK6fz6JuOZdUUZVX6Nt Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/03/26 1:32 pm, Lorenzo Stoakes (Oracle) wrote: > On Tue, Mar 10, 2026 at 01:00:04PM +0530, 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; >> } >> >> On arm64, only showing one of the middle values in the distribution: >> > > This doesn't seem very statistically valid. > > How about you give median, stddev etc.? Variance matters too. Okay. > >> without patch: >> madvise(MADV_PAGEOUT) took 52192959 ns (52.193 ms) >> >> with patch: >> madvise(MADV_PAGEOUT) took 26676625 ns (26.677 ms) > > You have a habit of only giving data on arm64, and not mentioning whether you've > tested on any other arch/setup. I did do an x86 build, forgot to mention that. I didn't do the numbers thinking this patchset is quite generic and has got nothing to do with the arm64 cont bit - but arguably I should have. > > I've commented on this before so I'm a bit disappointed you've done the exact > same thing here again. Especially since you've previously introduced regressions > this way. > > Please can you test this on (hardware!) x86-64 _at least_ as well and confirm > you aren't regressing anything for 4K pages? Lemme go and manage that :) > >> >> >> [1] https://lore.kernel.org/all/20250513084620.58231-1-21cnbao@gmail.com/ >> >> --- >> Based on mm-unstable bb420884e9e0. mm-selftests pass. >> >> Dev Jain (9): >> mm/rmap: make nr_pages signed in try_to_unmap_one >> mm/rmap: initialize nr_pages to 1 at loop start in try_to_unmap_one >> mm/rmap: refactor lazyfree unmap commit path to >> commit_ttu_lazyfree_folio() >> mm/memory: Batch set uffd-wp markers during zapping >> mm/rmap: batch unmap folios belonging to uffd-wp VMAs >> mm/swapfile: Make folio_dup_swap batchable >> mm/swapfile: Make folio_put_swap batchable >> mm/rmap: introduce folio_try_share_anon_rmap_ptes >> mm/rmap: enable batch unmapping of anonymous folios >> >> include/linux/mm_inline.h | 37 +++-- >> include/linux/page-flags.h | 11 ++ >> include/linux/rmap.h | 38 ++++- >> mm/internal.h | 26 ++++ >> mm/memory.c | 26 +--- >> mm/mprotect.c | 17 --- >> mm/rmap.c | 274 ++++++++++++++++++++++++------------- >> mm/shmem.c | 8 +- >> mm/swap.h | 10 +- >> mm/swapfile.c | 25 ++-- >> 10 files changed, 298 insertions(+), 174 deletions(-) >> >> -- >> 2.34.1 >>