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Tue, 16 Nov 2021 08:29:21 -0800 (PST) MIME-Version: 1.0 References: <20211019215511.3771969-1-surenb@google.com> <20211019215511.3771969-2-surenb@google.com> <89664270-4B9F-45E0-AC0B-8A185ED1F531@google.com> In-Reply-To: From: Suren Baghdasaryan Date: Tue, 16 Nov 2021 08:29:10 -0800 Message-ID: Subject: Re: [PATCH v11 2/3] mm: add a field to store names for private anonymous memory To: Michal Hocko Cc: akpm@linux-foundation.org, Alexey Alexandrov , ccross@google.com, sumit.semwal@linaro.org, dave.hansen@intel.com, keescook@chromium.org, willy@infradead.org, kirill.shutemov@linux.intel.com, vbabka@suse.cz, hannes@cmpxchg.org, corbet@lwn.net, viro@zeniv.linux.org.uk, rdunlap@infradead.org, kaleshsingh@google.com, peterx@redhat.com, rppt@kernel.org, peterz@infradead.org, catalin.marinas@arm.com, vincenzo.frascino@arm.com, chinwen.chang@mediatek.com, axelrasmussen@google.com, aarcange@redhat.com, jannh@google.com, apopple@nvidia.com, jhubbard@nvidia.com, yuzhao@google.com, will@kernel.org, fenghua.yu@intel.com, thunder.leizhen@huawei.com, hughd@google.com, feng.tang@intel.com, jgg@ziepe.ca, guro@fb.com, tglx@linutronix.de, krisman@collabora.com, chris.hyser@oracle.com, pcc@google.com, ebiederm@xmission.com, axboe@kernel.dk, legion@kernel.org, eb@emlix.com, gorcunov@gmail.com, pavel@ucw.cz, songmuchun@bytedance.com, viresh.kumar@linaro.org, thomascedeno@google.com, sashal@kernel.org, cxfcosmos@gmail.com, linux@rasmusvillemoes.dk, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Bj3MQbYK; spf=pass (imf22.hostedemail.com: domain of surenb@google.com designates 209.85.210.51 as permitted sender) smtp.mailfrom=surenb@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 453798BD30 X-Stat-Signature: r9hq7p1qgorckgjjxobhrgcm86m9bhin X-HE-Tag: 1637080502-764181 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: On Tue, Nov 16, 2021 at 1:51 AM Michal Hocko wrote: > > On Mon 15-11-21 10:59:20, Suren Baghdasaryan wrote: > [...] > > Hi Andrew, > > I haven't seen any feedback on my patchset for some time now. I think > > I addressed all the questions and comments (please correct me if I > > missed anything). > > I believe the strings vs. ids have been mostly hand waved away. The > biggest argument for the former was convenience for developers to have > something human readable. There was no actual proposal about the naming > convention so we are relying on some unwritten rules or knowledge of the > code to be debugged to make human readable string human understandable > ones. I believe this has never been properly resolved except for - this > has been used in Android and working just fine. I am not convinced TBH. > > So in the end we are adding a user interface that brings a runtime and > resource overhead that will be hard to change in the future. Reference > counting handles a part of that and that is nice but ids simply do not > have any of that. I explained the way this interface is used and why ids would not work for us in https://lore.kernel.org/all/CAJuCfpESeM_Xd8dhCj_okNggtDUXx3Nn9FpL_f9qsKXKZzCKpA@mail.gmail.com. I explored all the proposed alternatives, all of which would be prohibitive for our needs due to performance costs compared to this solution. I wish I could come up with something simpler but a simpler solution simply does not meet our needs. It's true that this approach does not formalize how VMAs are named but I don't see why kernel should impose a naming convention. I can see some systems defining more formal conventions but I believe it should be up to the userspace to do that. > > > Can it be accepted as is or is there something I should address > > further? > > Is the above reason to nack it? No, I do not think so. I just do not > feel like I want to ack it either. Concerns have been expressed and I > have to say that I would like a minimalistic approach much more. Also > extending ids into string is always possible. The other way around is > not possible. Unfortunately, extending ids into strings comes with the cost we can't afford in Android. Therefore I don't see a point for me to upstream such a solution which I can't use. Thanks, Suren. > > -- > Michal Hocko > SUSE Labs