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Shutemov" , David Rientjes , Vlastimil Babka , Hugh Dickins Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20230929114421.3761121-1-ryan.roberts@arm.com> From: John Hubbard In-Reply-To: <20230929114421.3761121-1-ryan.roberts@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: SJ0PR03CA0042.namprd03.prod.outlook.com (2603:10b6:a03:33e::17) To BY5PR12MB4130.namprd12.prod.outlook.com (2603:10b6:a03:20b::16) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BY5PR12MB4130:EE_|LV3PR12MB9214:EE_ X-MS-Office365-Filtering-Correlation-Id: 5aac6ea6-2399-45ac-91df-08dbe3fcb609 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 jB3N5i44 XhFF0WKexXg540pgKSDo0Ex4zgwSVdowiKzzHBfHiC70HwmLN27zc0wdDhFfd/wAh2eoEFZG/aJjJTWvEqkAf69jfYSOSy1QvrjXKS2K4BVW6uumH0u18oUMP8Hl1Vgc1NhdutzaMJC1FU3N3mceEO/kMhrCxyrOh2LNQh6+TsZZEwshusewqFmdrbgjzAdRLwLaXxLfoSDPTe1a2lRpvQz+Zdwn1ux9F4MDMRK9SZLCo9irhHIyUOBCwLcjZXn3sIezoweDSDf+JJKkOWG+EpFkvuNyJF1s3L5DnN8foqCJf8rmrkklxddHmrhSONKDspR/LlnHhc8IBZMfeTkx8EwI/og== 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 9/29/23 4:44 AM, Ryan Roberts wrote: > Hi All, > > This is v6 of a series to implement variable order, large folios for anonymous > memory. (previously called "ANON_LARGE_FOLIO", "LARGE_ANON_FOLIO", > "FLEXIBLE_THP", but now exposed as an extension to THP; "small-order THP"). The > objective of this is to improve performance by allocating larger chunks of > memory during anonymous page faults: ... > > The major change in this revision is the addition of sysfs controls to allow > this "small-order THP" to be enabled/disabled/configured independently of > PMD-order THP. The approach I've taken differs a bit from previous discussions; > instead of creating a whole new interface ("large_folio"), I'm extending THP. I > personally think this makes things clearer and more extensible. See [6] for > detailed rationale. > Hi Ryan and all, I've done some initial performance testing of this patchset on an arm64 SBSA server. When these patches are combined with the arm64 arch contpte patches in Ryan's git tree (he has conveniently combined everything here: [1]), we are seeing a remarkable, consistent speedup of 10.5x on some memory-intensive workloads. Many test runs, conducted independently by different engineers and on different machines, have convinced me and my colleagues that this is an accurate result. In order to achieve that result, we used the git tree in [1] with following settings: echo always >/sys/kernel/mm/transparent_hugepage/enabled echo recommend >/sys/kernel/mm/transparent_hugepage/anon_orders This was on a aarch64 machine configure to use a 64KB base page size. That configuration means that the PMD size is 512MB, which is of course too large for practical use as a pure PMD-THP. However, with with these small-size (less than PMD-sized) THPs, we get the improvements in TLB coverage, while still getting pages that are small enough to be effectively usable. These results are admittedly limited to aarch64 CPUs so far (because the contpte TLB coalescing behavior plays a big role), but it's nice to see real performance numbers from real computers. Up until now, there has been some healthy discussion and debate about various aspects of this patchset. This data point shows that at least for some types of memory-intensive workloads (and I apologize for being vague, at this point, about exactly *which* workloads), the performance gains are really worth it: ~10x ! [1] https://gitlab.arm.com/linux-arm/linux-rr.git (branch: features/granule_perf/anonfolio-v6-contpte-v2) thanks, -- John Hubbard NVIDIA