From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9B11914E2E7 for ; Tue, 7 May 2024 10:20:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715077230; cv=none; b=pDoXPVlSZC/Wp4wQIZISJq4Gthy1a0JxoHE/pSZ2m2eQ9fZs3i3ymBdreODhU25e0u8/vaKxQ1GchNjYMA0BwnytSS+M5oeih9ZI35lG/Mzy5Oc0DpbZ1cAMGId8ZOw8TxGEvo+DDGCKl88z57HUUCjJRaMPTambazPSeldmN7k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715077230; c=relaxed/simple; bh=l7a39ZOU+Mrj446gjZOKy3Bn0QGJfDOBT5AHwPvmWLg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Cwapg+3wDhVfkuADUsGv1WeW4bUXidtyjPscthBUc9sJOTOvUWmQwAs+scMRgL7nD+8/M058YbbuFjelg2RCv8jwNBKicrTOaHASqQl2n9TtgMnXJ+P3kH+gEwp9F/HfVKAOp4je7eIMkcZ6+KBnqghKo0Ax1hPACDQAKSwfJvs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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 B6D361063; Tue, 7 May 2024 03:20:53 -0700 (PDT) Received: from [10.1.34.181] (unknown [10.1.34.181]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 26B1B3F587; Tue, 7 May 2024 03:20:26 -0700 (PDT) Message-ID: Date: Tue, 7 May 2024 11:20:24 +0100 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 0/8] add mTHP support for anonymous shmem Content-Language: en-GB To: Baolin Wang , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, david@redhat.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, ying.huang@intel.com, 21cnbao@gmail.com, shy828301@gmail.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: From: Ryan Roberts In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 06/05/2024 09:46, Baolin Wang wrote: > Anonymous pages have already been supported for multi-size (mTHP) allocation > through commit 19eaf44954df, that can allow THP to be configured through the > sysfs interface located at '/sys/kernel/mm/transparent_hugepage/hugepage-XXkb/enabled'. > > However, the anonymous shared pages will ignore the anonymous mTHP rule > configured through the sysfs interface, and can only use the PMD-mapped > THP, that is not reasonable. Many implement anonymous page sharing through > mmap(MAP_SHARED | MAP_ANONYMOUS), especially in database usage scenarios, > therefore, users expect to apply an unified mTHP strategy for anonymous pages, > also including the anonymous shared pages, in order to enjoy the benefits of > mTHP. For example, lower latency than PMD-mapped THP, smaller memory bloat > than PMD-mapped THP, contiguous PTEs on ARM architecture to reduce TLB miss etc. > > The primary strategy is similar to supporting anonymous mTHP. Introduce > a new interface '/mm/transparent_hugepage/hugepage-XXkb/shmem_enabled', > which can have all the same values as the top-level Didn't we agree that "force" would not be supported for now, and would return an error when attempting to set for a non-PMD-size hugepage-XXkb/shmem_enabled (or indirectly through inheritance)? > '/sys/kernel/mm/transparent_hugepage/shmem_enabled', with adding a new > additional "inherit" option. By default all sizes will be set to "never" > except PMD size, which is set to "inherit". This ensures backward compatibility > with the shmem enabled of the top level, meanwhile also allows independent > control of shmem enabled for each mTHP. > > Use the page fault latency tool to measure the performance of 1G anonymous shmem > with 32 threads on my machine environment with: ARM64 Architecture, 32 cores, > 125G memory: > base: mm-unstable > user-time sys_time faults_per_sec_per_cpu faults_per_sec > 0.04s 3.10s 83516.416 2669684.890 > > mm-unstable + patchset, anon shmem mTHP disabled > user-time sys_time faults_per_sec_per_cpu faults_per_sec > 0.02s 3.14s 82936.359 2630746.027 > > mm-unstable + patchset, anon shmem 64K mTHP enabled > user-time sys_time faults_per_sec_per_cpu faults_per_sec > 0.08s 0.31s 678630.231 17082522.495 > > From the data above, it is observed that the patchset has a minimal impact when > mTHP is not enabled (some fluctuations observed during testing). When enabling 64K > mTHP, there is a significant improvement of the page fault latency. > > TODO: > - Support mTHP for tmpfs. > - Do not split the large folio when share memory swap out. > - Can swap in a large folio for share memory. > > Changes from RFC: > - Rebase the patch set against the new mm-unstable branch, per Lance. > - Add a new patch to export highest_order() and next_order(). > - Add a new patch to align mTHP size in shmem_get_unmapped_area(). > - Handle the uffd case and the VMA limits case when building mapping for > large folio in the finish_fault() function, per Ryan. > - Remove unnecessary 'order' variable in patch 3, per Kefeng. > - Keep the anon shmem counters' name consistency. > - Modify the strategy to support mTHP for anonymous shmem, discussed with > Ryan and David. > - Add reviewed tag from Barry. > - Update the commit message. > > Baolin Wang (8): > mm: move highest_order() and next_order() out of the THP config > mm: memory: extend finish_fault() to support large folio > mm: shmem: add an 'order' parameter for shmem_alloc_hugefolio() > mm: shmem: add THP validation for PMD-mapped THP related statistics > mm: shmem: add multi-size THP sysfs interface for anonymous shmem > mm: shmem: add mTHP support for anonymous shmem > mm: shmem: add mTHP size alignment in shmem_get_unmapped_area > mm: shmem: add mTHP counters for anonymous shmem > > Documentation/admin-guide/mm/transhuge.rst | 29 ++ > include/linux/huge_mm.h | 35 ++- > mm/huge_memory.c | 17 +- > mm/memory.c | 43 ++- > mm/shmem.c | 335 ++++++++++++++++++--- > 5 files changed, 387 insertions(+), 72 deletions(-) >