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AJvYcCVwIUlPRcHvS4d0XfzRiWB2FIdxHSAvMd8Pd7+Qh3JJi6y8msBJIJkxq9QdhjzQbQyBMEsU6XkMLiMAuv/jCuxT1ZQ= X-Gm-Message-State: AOJu0YyTcGsI25ut39AorEkZk5HIdoqdYVPfERSBIx3Vmw3+YEijkY/l Xw4lTn1gJZpmdATxGC63bQA2lE/X+7up1piPOTRG2MpUD8enJBvNnaHQsiQLMKkOepeWbdEAnu6 ja6Uv1Q0PfgS6TvPEvDL1k//avfmDFoK+4DSc X-Google-Smtp-Source: AGHT+IEq8Fs3z13ePwWrnbWJUDpx50btCGNNHylLrjkBr8g/csKK0P+GO3+xFEqljtHAVxZhGvPrjS68k6wXeE2cHVA= X-Received: by 2002:a05:600c:6546:b0:41f:9dd0:7168 with SMTP id 5b1f17b1804b1-4212c091f55mr2200815e9.2.1717173943952; Fri, 31 May 2024 09:45:43 -0700 (PDT) MIME-Version: 1.0 References: <20240529180510.2295118-1-jthoughton@google.com> <20240529180510.2295118-3-jthoughton@google.com> In-Reply-To: From: Yu Zhao Date: Fri, 31 May 2024 10:45:04 -0600 Message-ID: Subject: Re: [PATCH v4 2/7] mm: multi-gen LRU: Have secondary MMUs participate in aging To: Oliver Upton Cc: James Houghton , Sean Christopherson , Andrew Morton , Paolo Bonzini , Albert Ou , Ankit Agrawal , Anup Patel , Atish Patra , Axel Rasmussen , Bibo Mao , Catalin Marinas , David Matlack , David Rientjes , Huacai Chen , James Morse , Jonathan Corbet , Marc Zyngier , Michael Ellerman , Nicholas Piggin , Palmer Dabbelt , Paul Walmsley , Raghavendra Rao Ananta , Ryan Roberts , Shaoqin Huang , Shuah Khan , Suzuki K Poulose , Tianrui Zhao , Will Deacon , Zenghui Yu , kvm-riscv@lists.infradead.org, kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 9C6DD20015 X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: umejory531gwxwwurwfjh5z5dj1sgitr X-HE-Tag: 1717173945-497161 X-HE-Meta: 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 QLnKEpYS 31EeiMQEVlgmaPnvXDlWRUN0B1G1RpkHWv8GymoIp0HHyI8/qfbBzEVsgO0S5UUD+D8oNniSSR+x2/b+hGWkyhdTIdXlLerjTIBnFQ/m1iCzPl8mpUZkDqlFCEgO4cIT8qX7sw5nQtkJr0OG4nemsP5bG8rT0+DOGPwAGWuOUBknwl8aBeiSpInQSsTW8YvT8yoxPS0tjCu6ve+6bBgoUWNuHUgIVwtnepmMj 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 Fri, May 31, 2024 at 1:03=E2=80=AFAM Oliver Upton wrote: > > On Fri, May 31, 2024 at 12:05:48AM -0600, Yu Zhao wrote: Let me add back what I said earlier: I'm not convinced, but it doesn't mean your point of view is invalid. If you fully understand the implications of your design choice and document them, I will not object. > > All optimizations in v2 were measured step by step. Even that bitmap, > > which might be considered overengineered, brought a readily > > measuarable 4% improvement in memcached throughput on Altra Max > > swapping to Optane: > > That's great, but taking an iterative approach to the problem allows > the reviewers and maintainers to come to their own conclusions about > each optimization independently. Squashing all of that together and > posting the result doesn't allow for this. That's your methodology, which I respect: as I said I won't stand in your w= ay. But mine is backed by data, please do respect that as well, by doing what I asked: document your justifications. > Even if we were to take the series as-is, the door is wide open to > subsequent improvements. > > > What I don't think is acceptable is simplifying those optimizations > > out without documenting your justifications (I would even call it a > > design change, rather than simplification, from v3 to v4). > > No, sorry, there's nothing wrong with James' approach here. Sorry, are you saying "without documenting your justifications" is nothing wrong? If so, please elaborate. > The discussion that led to the design of v4 happened on list; you were > on CC. The general consensus on the KVM side was that the bitmap was > complicated and lacked independent justification. There was ample > opportunity to voice your concerns before he spent the time on v4. Please re-read my previous emails -- I never object to the removal of the bitmap or James' approach. And please stop making assumptions -- I did voice my concerns with James privately. > You seriously cannot fault a contributor for respinning their work based > on the provided feedback. Are you saying I faulted James for taking others' feedback? If so, where? And I'll make sure I don't give such an impression in the future. Also what do you think about the technical flaws and inaccurate understandings I pointed out? You seem to have a strong opinion on your iterate approach, but I hope you didn't choose to overlook the real meat of this discussion.