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[2003:cb:c737:4900:68b3:e93b:e07a:558b]) by smtp.gmail.com with ESMTPSA id 21-20020a05600c22d500b003f96d10eafbsm9778433wmg.12.2023.06.27.00.14.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 27 Jun 2023 00:14:31 -0700 (PDT) Message-ID: Date: Tue, 27 Jun 2023 09:14:29 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH v6 00/33] Split ptdesc from struct page To: Hugh Dickins , "Vishal Moola (Oracle)" References: <20230627031431.29653-1-vishal.moola@gmail.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, linux-sh@vger.kernel.org, Catalin Marinas , Dave Hansen , linux-openrisc@vger.kernel.org, Matthew Wilcox , sparclinux@vger.kernel.org, linux-riscv@lists.infradead.org, Claudio Imbrenda , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, Yoshinori Sato , linux-hexagon@vger.kernel.org, Huacai Chen , linux-csky@vger.kernel.org, Geert Uytterhoeven , xen-devel@lists.xenproject.org, Jonas Bonn , Arnd Bergmann , linux-um@lists.infradead.org, linux-m68k@lists.linux-m68k.org, loongarch@lists.linux.dev, Paul Walmsley , linux-arm-kernel@lists.infradead.org, Thomas Bogendoerfer , linux-mm@kvack.org, linux-mips@vger.kernel.org, Dinh Nguyen , Richard Weinberger , Andrew Morto n , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 27.06.23 06:44, Hugh Dickins wrote: > On Mon, 26 Jun 2023, Vishal Moola (Oracle) wrote: > >> The MM subsystem is trying to shrink struct page. This patchset >> introduces a memory descriptor for page table tracking - struct ptdesc. > ... >> 39 files changed, 686 insertions(+), 455 deletions(-) > > I don't see the point of this patchset: to me it is just obfuscation of > the present-day tight relationship between page table and struct page. > > Matthew already explained: > >> The intent is to get ptdescs to be dynamically allocated at some point >> in the ~2-3 years out future when we have finished the folio project ... > > So in a kindly mood, I'd say that this patchset is ahead of its time. > But I can certainly adapt to it, if everyone else sees some point to it. I share your thoughts, that code churn which will help eventually in the far, far future (not wanting to sound too pessimistic, but it's not going to be there tomorrow ;) ). However, if it's just the same as the other conversions we already did (e.g., struct slab), then I guess there is no reason to stop now -- the obfuscation already happened. ... or is there a difference regarding this conversion and the previous ones? -- Cheers, David / dhildenb