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Thu, 09 Mar 2023 18:16:29 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Yosry Ahmed Date: Thu, 9 Mar 2023 18:15:52 -0800 Message-ID: Subject: Re: [LSF/MM/BPF TOPIC] Swap Abstraction / Native Zswap To: Luis Chamberlain Cc: lsf-pc@lists.linux-foundation.org, Johannes Weiner , Linux-MM , Michal Hocko , Shakeel Butt , David Rientjes , Hugh Dickins , Seth Jennings , Dan Streetman , Vitaly Wool , Yang Shi , Peter Xu , Minchan Kim , Andrew Morton , Anthony Iliopoulos , Davidlohr Bueso , Adam Manzanares Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 1816420016 X-Rspamd-Server: rspam01 X-Stat-Signature: sdkrhbb9fs1mz4m67bdhzcc6rc5jqegy X-HE-Tag: 1678414590-806985 X-HE-Meta: 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 0ybWucN5 iH8ZETeNtGn5NBBAIkdSVvvUKPsmUIY50rHSIya8Ee2V/Lp+ICfFzIvJsUtfmzwwKCR/kaB0ki5PdkuMB+pq/qVDiV3NUdkj+EZYsd45NYTYzIVjAL7yiSKDLBdHE8EIdPAYjrbODEKuoKENZUinTh5UzwJrawnXfDoka8Sf6tmF1r3+JeA+aUa210V1THVujUDGzG79TaSxpoKs91hdzP0DZBPGGTK+sPk+llpv//fORbQUHHE7gMsqnf0qi44ciCpZq0EUWdgaEmX6x5SmX3mKXjmTAXLII5IPNtjxeXPFGnTPYv+3bZA3B2QagQPzJ7TtMnQKJgh9amO58oApql1Wj1a5x7/J3I/RTT/w87yu2CG9j37k5EbPjDhpE0ygj+6d355kWIFY4ylVv6wYla0YUp8CtiuxfYkuP X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Mar 9, 2023 at 6:08=E2=80=AFPM Luis Chamberlain = wrote: > > On Sat, Feb 18, 2023 at 02:38:40PM -0800, Yosry Ahmed wrote: > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Intro =3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > Currently, using zswap is dependent on swapfiles in an unnecessary > > way. To use zswap, you need a swapfile configured (even if the space > > will not be used) and zswap is restricted by its size. > > There's also overlap with zram too. zswap uses zpool and so does its > compression backends (zbud, zsmalloc, z3fold), but zram does not. Vitaly > did a great job at presenting some overlap between all this before, so > perhaps we can summon him as I'd imagine he'd be interested. > > https://lpc.events/event/4/contributions/551/attachments/364/597/zram-dec= ouple.pdf Yes. Hopefully by making zswap independent from swapfiles we partially bridge the gap between zswap and zram. > > FWIW we've been using zswap with the whole intention of *never* touching > disk on purpose for years now on kdevops with the goal to just do compres= sion > of memory and avoid having to mess with a block device as preamble. This = is > done on the hypervisor with tons of guests, that together with KSM saves = *huge* > amount of memory: > > https://github.com/linux-kdevops/kdevops/blob/master/docs/kernel-ci/kerne= l-ci-hypervisor-tuning.md At Google, we have been also using zswap without writeback for years. It's great to hear that others share the same use case. Perhaps it's finally time to properly support this use case upstream. > > Luis