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[96.255.20.138]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8942e47d897sm548586d6.0.2026.01.15.09.33.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Jan 2026 09:33:15 -0800 (PST) Date: Thu, 15 Jan 2026 12:32:41 -0500 From: Gregory Price To: Yosry Ahmed Cc: Nhat Pham , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-cxl@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@meta.com, longman@redhat.com, tj@kernel.org, hannes@cmpxchg.org, mkoutny@suse.com, corbet@lwn.net, gregkh@linuxfoundation.org, rafael@kernel.org, dakr@kernel.org, dave@stgolabs.net, jonathan.cameron@huawei.com, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, ziy@nvidia.com, david@kernel.org, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, rppt@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, yury.norov@gmail.com, linux@rasmusvillemoes.dk, rientjes@google.com, shakeel.butt@linux.dev, chrisl@kernel.org, kasong@tencent.com, shikemeng@huaweicloud.com, bhe@redhat.com, baohua@kernel.org, chengming.zhou@linux.dev, roman.gushchin@linux.dev, muchun.song@linux.dev, osalvador@suse.de, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com, cl@gentwo.org, harry.yoo@oracle.com, zhengqi.arch@bytedance.com Subject: Re: [RFC PATCH v3 7/8] mm/zswap: compressed ram direct integration Message-ID: References: <20260108203755.1163107-1-gourry@gourry.net> <20260108203755.1163107-8-gourry@gourry.net> <4ftthovin57fi4blr2mardw4elwfsiv6vrkhrjqjsfvvuuugjj@uivjc5uzj5ys> Precedence: bulk X-Mailing-List: cgroups@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 Thu, Jan 15, 2026 at 05:00:04PM +0000, Yosry Ahmed wrote: > > > > 2. Just enable zswap shrinker and have memory reclaim move these pages > > into disk swap. This will have a much more drastic performance > > implications though :) > > I think what you're getting it as that we can still make forward > progress after memory lands in compressed cxl. But moving memory to > compressed cxl is already forward progress that reclaim won't capture if > we charge memory as a full page. I think this is the crux of the issue. > > We need to figure out how to make accounting work such that moving > memory to compressed cxl is forward progress, but make sure we don't > break the overall accounting consisteny. If we only charge the actual > compressed size, then from the system perspective there is a page that > is only partially charged and the rest of it is more-or-less leaked. Which is comically fine - because the actual capacity of the node is functionally a lie anyway :D ~Gregory