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[130.237.96.130]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5b8d857f7edsm1229650e87.31.2026.09.24.00.20.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 24 Sep 2026 00:20:07 -0700 (PDT) Date: Thu, 24 Sep 2026 09:20:06 +0200 From: Klara Modin To: Baoquan He Cc: Chris Li , Rik van Riel , Gregory Price , Johannes Weiner , Nhat Pham , Kairui Song , Michal Hocko , Roman Gushchin , Shakeel Butt , Yosry Ahmed , David Hildenbrand , Muchun Song , Kemeng Shi , Barry Song , YoungJun Park , Chengming Zhou , "Lorenzo Stoakes (Oracle)" , "Liam R. Howlett" , "Vlastimil Babka (SUSE)" , Mike Rapoport , Suren =?utf-8?B?QmFnaGRhc2FyeWFu77+8?= , Qi Zheng , Axel Rasmussen , Yuanchu Xie , Wei Xu , Wenchao Hao , Jonathan Corbet , Hugh Dickins , Baolin Wang , Tejun Heo , Michal =?utf-8?Q?Koutn=C3=BD?= , Shuah Khan , Kunwu Chan , Meta kernel team , Linux Memory Management List , Linux Kernel Mailing List , linux-doc@vger.kernel.org, "open list:CONTROL GROUP - MEMORY RESOURCE CONTROLLER (MEMCG)" , Andrew Morton , Kairui Song , Joshua Hahn Subject: Re: Path forward for Virtualized Swap? Message-ID: References: <785353ef79844e81a8cd97e87b00ef1f785b15e5.camel@surriel.com> <83539be885f15bb567b30264f5f62e718f4a9fd0.camel@surriel.com> <5a7ad159b2fabf377b7e1fc4248c433287ac11fb.camel@surriel.com> 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 2026-09-24 13:51:50 +0800, Baoquan He wrote: > On 09/23/26 at 02:52pm, Klara Modin wrote: > > Hi, > > ... > > > > Chiming in as more of a user perspective. > > > > On my 4 GiB BPI-F3, I can reach more than 10:1 compression ratio on > > zswap during some parts when building GCC 17 snapshots. E.g: > > > > MemTotal: 3966864 kB > > SwapCached: 31872 kB > > SwapTotal: 16777212 kB > > SwapFree: 16638128 kB > > Zswap: 280140 kB > > Zswapped: 2859840 kB > > AnonPages: 2927376 kB > > AnonHugePages: 1409024 kB > > > > While this is 72 % rather than the 100 % you asked for, I think this > > shows that what size a potential limit on the uncompressed size of zswap > > is suitable heavily depends on the workload. > > > > I have been using vswap consistently on all my machines since about > > August, and I have also tried one or two versions of xswap (but the > > current lack of writeback makes it inconvenient for me). I really > > Thanks for testing xswap and reporting issue on xswap rfc v3. > > xswap has writeback now. I only built foundation for xswap, while > writeback part was left to other people for collaboration. Finally > I added it. > > [RFC PATCH 00/17] mm, swap: xswap writeback to a physical backend > https://lore.kernel.org/all/20260920072043.430390-1-hebaoquan@kylinos.cn/T/#u > Thanks, I'll give it another try when I have time. > > > appreciate the work being put in to decouple zswap from needing a > > physical swap device to work. > > ... > > > > My personal preference would be for a default uncapped (or very high, > > and I don't think 100 % of RAM is high) limit on the uncompressed data > > which is backed by zswap, since that would mean one less knob to tune. > > > > > > > > Chris > > > > Regards, > > Klara Modin