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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id af79cd13be357-8c37f51cf95sm1746353885a.33.2026.01.13.06.41.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Jan 2026 06:41:21 -0800 (PST) Date: Tue, 13 Jan 2026 09:40:48 -0500 From: Gregory Price To: Bharata B Rao Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Jonathan.Cameron@huawei.com, dave.hansen@intel.com, mgorman@techsingularity.net, mingo@redhat.com, peterz@infradead.org, raghavendra.kt@amd.com, riel@surriel.com, rientjes@google.com, sj@kernel.org, weixugc@google.com, willy@infradead.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, dave@stgolabs.net, nifan.cxl@gmail.com, xuezhengchu@huawei.com, yiannis@zptcorp.com, akpm@linux-foundation.org, david@redhat.com, byungchul@sk.com, kinseyho@google.com, joshua.hahnjy@gmail.com, yuanchu@google.com, balbirs@nvidia.com, alok.rathore@samsung.com, shivankg@amd.com Subject: Re: [RFC PATCH v4 0/9] mm: Hot page tracking and promotion infrastructure Message-ID: References: <20251206101423.5004-1-bharata@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2DA6740016 X-Stat-Signature: wwhz7dmn8grdsaogzyj6yxg4y59536s3 X-HE-Tag: 1768315283-37461 X-HE-Meta: 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 5Y+1vL/M D+Y1BZS7wpWj5mu7iKfs95UH5AyKgdSpWw9QQq2VKdtQ0+JZJ23XvrOuejk5MHSjakcO0N+F4k4XO2xKgB3EyJn23DjTiipTh0ESGN3zob+AClH6jxZOQkGji/nR9ar3LRKjnAzgcs7DJGHHGDfbfKYFGAWtx1cm3M+VLAPP0b/HeffJOi5e5aZZ+ed4JpgFktIs3KrRTggXZGXHQx84M2sqfJjQau+UwhkDe3UfNPeqnc3l/l3wJGKXCWg7IqMX6WBWqsHCqRCc+TTZkGxEoBa/bnjnjJ2JJkBS5XYVGxQ7aulNNh2G0BbL23CMNlVQxO5e7dJS267vRewji8w8bD7d6IPUtI/3OG7ndSEMXTpXLsf8LrUJpJ21VRI8eVkviKXNJ7fgMm/q9eQMGrOEW8QsEzA== 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 Tue, Jan 13, 2026 at 08:08:34PM +0530, Bharata B Rao wrote: > On 13-Jan-26 7:54 PM, Gregory Price wrote: > > On Sat, Dec 06, 2025 at 03:44:14PM +0530, Bharata B Rao wrote: > >> Hi, > >> > >> This is v4 of page hotness tracking and promotion sub-system pghot. > >> > > > > Just fyi, we haven't started real workload testing, but we're setting > > up the process soon. Just wanted to let you know it's on the radar. > > > > We want to test this at the same time with some fixes we've been > > working on for multi-tenant fairness in the demotion/reclaim path. > > Thanks Gregory for taking this up for testing. > > I am working on v5 with following enhancements: > > 1. Default mode: 1 byte per PFN for storing hotness info. NID isn't stored but > promotion will be done to a default toptier node(specifiable via sysfs/debugs). > Frequency and time are stored but due to paucity of bits, I will have to use > some sort of bucketing scheme for storing time like how current hot page > promotion logic does. > > 2. Precision mode: 4 bytes or 32bits per PFN where NID is stored in addition to > time and frequency. > > 2 is completed and 1 is in the works. Once I get it working correctly, I will > post v5. > > Since there were a few bugs in v4, I think it makes sense to start testing on v5 > itself. > Can do, thanks for the heads up, we'll wait for v5. Cheers, Gregory