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Fri, 15 Dec 2023 01:50:37 -0800 (PST) X-Google-Smtp-Source: AGHT+IEj0WCc7h2W06gwb0544zgPnIeghTyp6d8BMs+Gqvk9Yl1q2nTxcxfziVYO7Ty/itdzxF+rd+Jc9exaxn2+BMo= X-Received: by 2002:a0d:f842:0:b0:5d7:1940:b377 with SMTP id i63-20020a0df842000000b005d71940b377mr9389520ywf.67.1702633836737; Fri, 15 Dec 2023 01:50:36 -0800 (PST) MIME-Version: 1.0 References: <20231207192406.3809579-1-nphamcs@gmail.com> <20231209034229.GA1001962@cmpxchg.org> <20231214171137.GA261942@cmpxchg.org> In-Reply-To: From: Fabian Deutsch Date: Fri, 15 Dec 2023 10:50:16 +0100 Message-ID: Subject: Re: [PATCH v6] zswap: memcontrol: implement zswap writeback disabling To: Chris Li Cc: Yu Zhao , Johannes Weiner , Minchan Kim , Nhat Pham , "akpm@linux-foundation.org" , "tj@kernel.org" , "lizefan.x@bytedance.com" , "cerasuolodomenico@gmail.com" , "yosryahmed@google.com" , "sjenning@redhat.com" , "ddstreet@ieee.org" , "vitaly.wool@konsulko.com" , "mhocko@kernel.org" , "roman.gushchin@linux.dev" , "shakeelb@google.com" , "muchun.song@linux.dev" , "hughd@google.com" , "corbet@lwn.net" , "konrad.wilk@oracle.com" , "senozhatsky@chromium.org" , "rppt@kernel.org" , "linux-mm@kvack.org" , "kernel-team@meta.com" , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "david@ixit.cz" , Kairui Song , Zhongkun He X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6B4CFC000A X-Stat-Signature: 7x4a7rpzzkeone1gi9yq5agjqs5cxhn8 X-HE-Tag: 1702633839-991354 X-HE-Meta: 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 WEiCE4hi ODXVMhr/75h1/lsMkziINSPFEtAkxcEqBH72DFwHiDs3S/h3rqDN2CnmHPc9UB2h8fIoVYMhQLCVEJ97GShqDZiXSRBXlqu3k293qQiyVd0FCy2s7lnhAa8Uq5NdHOLACCdNwGpaPSo4COgQgvgDwDnPvhgG8reXNcvubm+ea390m8tK3osiLmd6phAeClVSyUVwgNF9eQ0FVgGYpZDOQtYXfBdg18/GxIXCl75v5LlARjOD2Jp8BjVZRWOKmivt9uQ5TGc10I3Wp7Br4SNWy4RLDEjjrlk4jYboIoyCPMtJMvowc0sdIFGbv5L68PL3Cw1wKeYahT1hI9ZjK7VcEHOBv0x6EmFOO7sUHT3xupDPYd+09TuZtcmv84Q== 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: List-Subscribe: List-Unsubscribe: On Fri, Dec 15, 2023 at 10:40=E2=80=AFAM Chris Li wrote= : > > On Thu, Dec 14, 2023 at 11:42=E2=80=AFPM Fabian Deutsch wrote:. > > > > > > Just to clarify, the "node" you mean the "node" in kubernetes sense, > > > which is the whole machine. In the Linux kernel MM context, the node > > > often refers to the NUMA memory node, that is not what you mean here, > > > right? > > > > Correct, I was referring to a kubernetes node, not numa node. > > > > > > > >> - With todays node level swap, and setting memory.swap.max=3D0 for a= ll cgroups allows you toachieve a similar behavior (only opt-in cgroups wil= l get swap). > > >> - the above approach however will still have a shared swap backend f= or all cgroups. > > > > > > Yes, the "memory.swap.tires" idea is trying to allow cgroups to selec= t > > > a subset of the swap backend in a specific order. It is still in the > > > early stage of discussion. If you have any suggestion or feedback in > > > that direction, I am looking forward to hearing that. > > > > Interesting. There have been concerns to leak confidential data acciden= tally when it's getting written to a swap device. > > One common solution is to encrypt the data written to the device. If > someone gets hold of the swapped outed device without the key, they > can't get to the memory data without the key. Yes - I guess like writing it onto a dmcrypt device with some random key. Nevertheless, this was one of the topics. > > > > The other less discussed item was QoS for swap io traffic. > > > > At a first glance it seems like tires could help with the second use-ca= se. > > The idea is that you can select the swap tiers list for each cgroup. > That way you can assign different swap QoS to different cgroup. Yes, it sounds like a fit. What use-cases did you have in mind for the tiers feature?