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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8997c6bba49sm78730156d6.15.2026.02.23.07.02.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 Feb 2026 07:02:34 -0800 (PST) Date: Mon, 23 Feb 2026 10:02:30 -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 v5 00/10] mm: Hot page tracking and promotion infrastructure Message-ID: References: <20260129144043.231636-1-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 Mon, Feb 23, 2026 at 07:57:39PM +0530, Bharata B Rao wrote: > > Time in seconds - Lower is better > Mop/s total - Higher is better > ===================================================================================== > Base Base pghot-default > pghot-precise > NUMAB0 NUMAB2 NUMAB2 NUMAB2 > ===================================================================================== > Time in seconds 7349.86 4422.50 6219.71 4113.56 > Mop/s total 53247.66 88493.630 62923.030 95139.810 > > pgpromote_success 0 42181834 248503390 41955718 > pgpromote_candidate 0 0 577086192 0 > pgpromote_candidate_nrl 0 42181834 29410329 41956171 > pgdemote_kswapd 0 0 216489010 0 > numa_pte_updates 0 42252749 607470975 42037882 > numa_hint_faults 0 42183772 606540729 41968150 > ===================================================================================== > > - In the base case, the benchmark numbers improve significantly due to hot page > promotion. > - Though the benchmark runs for hundreds of minutes, the pages get promoted > within the first few mins. > - pghot-precise is able to match the base case numbers. > - The benchmark suffers in pghot-default case due to promotion being limited > to the default NID (0) only. This leads to excessive PTE updates, hint faults, > demotion and promotion churn. Wow, this really seems to justify the extra memory usage. Is it possible for you to change pghot-default to move the page to a random (or round-robin) node on the top tier instead of NID(0) by default? At least then pghot-default would be correct 1/N % of the time (in theory). I'd be curious to see how close it gets to NUMAB2 with that. ~Gregory