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Tue, 22 Sep 2026 08:43:42 -0700 (PDT) Date: Tue, 22 Sep 2026 11:43:39 -0400 From: Johannes Weiner To: Chris Li Cc: Rik van Riel , Gregory Price , Baoquan He , 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 =?iso-8859-1?Q?Koutn=FD?= , 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam06 X-Stat-Signature: p4yba81z3sz6pxdsrbffx5yg5tzqqzhh X-Rspam-User: X-Rspamd-Queue-Id: 79E8580002 X-HE-Tag: 1790091824-221245 X-HE-Meta: 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 ttjyQAEu w/1rsEMKvBjgyf8thDOWnDcOZFXQcWAQnjpZngL6sFpVGCAiLI/KJIlcykFxa7yxzc5cx5Vuy2bIK5OVCtzQsPTJ20BbvC4/KWkw67fuJew4XAI5ugGt5Fn40R07960YJVRIYhbPV/jyhKHjPZO5RlZJpOQ86sc2tFyle+Z1u9kpftKDyRHaRxNgHCvyYSaBg6kMPt46ITQc2KsSmLGmaopoeqte6VPuRUuY6/ztqLvcUsK4HwYt0WHqEtm8EdXsOZrlUousN+SejiwTx1bsI6klA0oWEqzTrucJ+s7q2jtiBrDZwNK3xJ9+Of0/ZMIaW7kOAkJtDoPKOywBvM4xGs5siY2zDGzRH8XnuqG2C9pAxg2jIol2fxU4wGBsblVPn45p7S0AlsEvbBGdMpwpdUTbv7lQ0NBgVYUbK7svC1bcmCKprQ215v9so+j1PF55Vs8ez+NH8Azb7PAMOvqvoopBvlGLeRwmzSs3vITeCTNDNYAitd4Kf7wUSqK3BPqHgu/CE22jxCqcxku4= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 22, 2026 at 05:23:31AM -1000, Chris Li wrote: > In my experiment, 100% is already way above that bound, which is why > I'm curious about your data point. How do you run and test your system > at 100%? Please correct me if I am wrong, but it looks like you > haven't. You're conflating machine size with workingset residency. Rik showed an example where the compressed set was twice as large as the anon set, and it worked fine. And why is that surprising? We know many applications have long tails of cold pages. Idle tmpfs files and shmem segments. Things that get rarely used. memcache style workloads have a small, hot index and a huge data segment with poor access locality. Even if large parts of it are in compressed space that's better than storage fetches. Your "this will thrash after 7-10%" is an average based on common workingsets that are actually hot. It doesn't mean there aren't cases that benefit from much higher overcommit. Why even get into this? Why even try to find some universal limit on something that just costs memory anyway, when memory containment is already a solved problem?