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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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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