From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4982AC55171 for ; Sun, 2 Aug 2026 16:08:20 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D9CF36B007B; Sun, 2 Aug 2026 12:08:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D4E566B0088; Sun, 2 Aug 2026 12:08:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C647E6B008A; Sun, 2 Aug 2026 12:08:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 9DA506B007B for ; Sun, 2 Aug 2026 12:08:18 -0400 (EDT) Received: from smtpin04.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 2791C160516 for ; Sun, 2 Aug 2026 16:08:18 +0000 (UTC) X-FDA: 85056811476.04.E904A6F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf16.hostedemail.com (Postfix) with ESMTP id 7658E180003 for ; Sun, 2 Aug 2026 16:08:16 +0000 (UTC) Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=fViHsPsw; spf=pass (imf16.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1785686896; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=H+4xx3fRKee1b0QajtvgZv/bFYWSicihtcsfxKrpyj8=; b=m6aa55Q6PUM1MEKMjIy2nVQR7uz6f63n+6YNn0kG+YDMikcCq6d8jvggwp5GNiZEvieVHK rr6skQBDAbI/9k3VAfeTTE98GWwdqsz/SoVRS+oQtSXqlm4jbaiUXyCblnHvcYFS/xGHTG BINm03kFmSfwEyC7JOX2rN8dYEAjFfE= ARC-Authentication-Results: i=1; imf16.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=fViHsPsw; spf=pass (imf16.hostedemail.com: domain of sj@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1785686896; b=p2kFV4USisUFhFybkDFUh4RtDHYtKKGhi3PDEnivTHK06KoPuMbFHHFtjr+RiAsnCj39ev 1aPHQPSAUsT9vNaibJ+k9DjfpntPh5Wsflt8ZHwqMRwsNKwcOrpsGNojnaLlzrQP/N/dLQ e3hDXbpSrgqLudICRXNWkglBC4IAX4U= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 44BBB40F11; Sun, 2 Aug 2026 16:08:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A56271F000E9; Sun, 2 Aug 2026 16:08:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785686895; bh=H+4xx3fRKee1b0QajtvgZv/bFYWSicihtcsfxKrpyj8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=fViHsPswWigTKEfPBToFcw3DBd7G4MxypKk/ObN08SNRwfIiSmB1gi58BxY634oTS xhYBJ+W7P76Del+d1V7R746QWJ78Z3CXuTXnLUV36MKbq+smBuiZ7QtNnkOSLfiyRG iR0iSBZRvR+u4doaVnz2BhahCK0dqGkdTWfgPYTfkB4663fXF0CjqEy/0/fDFHoNf4 HVYE+1sPqqQr3lV20HM1tOfTLYPCEt141ysP99Zn0nM6lgDhLuS2NwJE7+qmnpPcOy 7l7nEOSihJlcHapONkZ4xBGdIfVJGu+j2hgR/mS9vxOd9b4eEjb+2povUvxI5HTGVT JMM5BTeXywfUQ== From: SJ Park To: David Rientjes Cc: SJ Park , Davidlohr Bueso , Fan Ni , Frank van der Linden , Gregory Price , Jonathan Cameron , Joshua Hahn , Raghavendra K T , "Rao, Bharata Bhasker" , Wei Xu , Xuezheng Chu , Yiannis Nikolakopoulos , Zi Yan , linux-mm@kvack.org Subject: Re: [Linux Memory Hotness and Promotion] Notes from July 30, 2026 Date: Sun, 2 Aug 2026 09:08:10 -0700 Message-ID: <20260802160811.88983-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 7658E180003 X-Rspamd-Server: rspam01 X-Stat-Signature: xs3abpw7y7crur9ih8m4pdr3c3nu17dd X-HE-Tag: 1785686896-304437 X-HE-Meta: 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 6rIbPloo 2Y/YrNq7jPP2msaxW04N00wkBPJIdfg3WErWqLK6//fatdUu7vZeJv0WPFFgJFasTIwmhseyDjoeow3HV8OLLiyADG6E5G70lUk+J43qW2ULRtxU2UOb4Rjbne9U0wKdsraHmy92QhlJ2p1MhGFb7itnb7BPd3iuxGZd8RllmaRL990bVtgRZxAdEo1KoAq8Bd6J4/wXNFORCkIx52g2ss0KOFwAKAYkRqBi/+WAfzc7qDxVTiSIjO1lOGjQZSRqJqopoMY247TyMbZemjFc0qdHOumXQkIZbxnIAzH8K4IQGPUgMDFc9LuxL3VehGM4byVgH9KopC4RtORfhwtMqDLEavdzlwoq2uIFKW2k/JHAZ2v1pRSvXpEpFTjI/jHnGc4us/K86wCLZ35wl9jkGKyX/JQUA5qR/rxHHJjxMltt5qE/xKORLyUVMxFwRGxfSpMzK3OlAsjnaHtuZpTZUUq/Cmhlk6Bi36gOh Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sat, 1 Aug 2026 20:40:35 -0700 (PDT) David Rientjes wrote: > Hi everybody, > > Here are the notes from the last Linux Memory Hotness and Promotion call > that happened on Thursday, July 30. Thanks to everybody who was involved! > > These notes are intended to bring people up to speed who could not attend > the call as well as keep the conversation going in between meetings. Thank you for sharing this note, David. This is so helpful! [...] > Bharata updated on the status of his v8 patch series. He has posted it > with some numbers and did not observe any regressions when comparing NUMAB > with pghot. The initial goal is to upstream the support for the tiering > subsystem regardless of the number of page hotness sources. Thus, the > upstreaming story will be about clean up and refactoring to support > tiering; David Hildenbrand had suggested that the current approach was too > extensive. > > Bharata was also looking into performance numbers asynchronously. Gregory > had been vocal on why this patch series is needed upstream, but any > additional use cases and support for the upstream series would be > beneficial. > > ----->o----- > There was discussion about what overlap this work had with DAMON. I should have attended the meeting, sorry. I show some rooms to improve clarifications. Let me add a few comments. > DAMON > was noted as being highly complex I admit there are many complicated parts in DAMON. We therefore actively working on this. We develop auto-tuning and simplified alternative features for users. We cleanup and refacor the code for developers. It would be nice if I could further learn what makes people feel this way, and wht can we change in DAMON to make it simplified. > and we reflected on previous examples > where this was a similar story upstream. Wei suggested that memory > tiering should be supported in the core MM and not something external. I think this could better be clarified. What is the definition of core MM, and why it is beneficial to have the support inside it? > He > also suggested that we wanted to support hotness signals from hardware > (like CHMU) and fix the promotion side but that does not require extending > DAMON specifically. Nobody in the call suggested that they were working on > productionizing DAMON at this time. We shared the plan [1] to extend DAMON for multiple access primitives (a.k.a source) other than page table accessed bit in LSFMMBPF'25. A few people showed interest. Amazon and Micron publicly showed their interest. There were few more companies showed interest offline. We therefore kept working on it. Recently a concrete plan with timeline [2] is made, and we are working on it. Quite amount of preparational changes are already upstreamed and working prototypes are shared. > > Gregory suggested that our focus should be on generic support in the > kernel that ensures that we can handle these memory topologies correctly > and without extensive configurations, including from userspace. Wei > strongly agreed with this. I fully agree with this. I shared my plan [3] for doing that for not only tiering but general NUMA topologies in LPC'25. I will try to join the next call for more conversations. But feel free to ask any questions on the mailing list or privately to me, at anytime. [1] https://lwn.net/Articles/1016525/ [2] https://lore.kernel.org/all/20260525225208.1179-1-sj@kernel.org/ [3] https://lpc.events/event/19/contributions/2066/ Thanks, SJ [...]