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t=1680040884; bh=jUBIC7Sc+iPgVT9gHDQeN68lIpi9Snj+LspClgfqvr8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mjhr/j5vratBXuceuVIFNG7DIsga4eCcq6ZEVY+hHyPZO8kNLXIHMfolTrjeVnI3n 68iG7xegaoIUCrtFB4t+Ui8gkTK5EttAh8tzuzKm1tOOJjQWH0V9hi2VVFK8nFNo// R+ULzKwoJexhBqDR2rZPcIzDRmjwyNal7drDUv33mABQKrg801D6MkT2CQefxtTA9q aZCK3Ps1rD6eMxLDvrblwFbyzgxl86v1HFlnuE2e7OLfCQRK+0m/pE/BG8837EvITn /mNWptWyeLsckP95e39rGLB2MLboqdqPPeQ2M75kO1Gr0o7aUxw/UCJUS6USdaqVTw Unv8Nk0AQRB1g== Date: Tue, 28 Mar 2023 15:01:22 -0700 From: Chris Li To: Yosry Ahmed Cc: "Huang, Ying" , 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 , Aneesh Kumar K V , Michal Hocko , Wei Xu Subject: Re: [LSF/MM/BPF TOPIC] Swap Abstraction / Native Zswap Message-ID: References: <87edpbq96g.fsf@yhuang6-desk2.ccr.corp.intel.com> <87jzz1pfb3.fsf@yhuang6-desk2.ccr.corp.intel.com> <87fs9ppdhz.fsf@yhuang6-desk2.ccr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: u9168r9ayy58ebu5e9bjqoc6kxdttywr X-Rspam-User: X-Rspamd-Queue-Id: B8A8840026 X-Rspamd-Server: rspam06 X-HE-Tag: 1680040887-91511 X-HE-Meta: U2FsdGVkX1/3PZrnRiA65syBUg9LQs18HP480vI1Lhj5GBNUBAC8tFb9W6gTlGRo+5zatjjVQpMeD2M+J5ScebY/pGdawcSrGZsWleeRGQFBvC3UVz2YwHfOyECG2VjHZs4eMKYjnq3ny1MH+GU9hIbySYiXR4736SFXa5C85DvmnYCq0y1SIJorJrNyvp0qRcD7DS1IHpQGW6nbAsi377b18af/wY+edLF2I9RQ9HjAeohOLcJx2gGruwxqv9UHQmdplvpZfGdleqsz5A1SxkYyFIV+pAnNHPkMuVsG84CGp0wz6Yj3EO9XuXZCi5w76ohzO6kcLX6Y7ZWGKDW3kOUP6V9mv4Nr8TdD1GMZSdRtQ/M4vUTy5dUKf3Pd23HuGrcpEdHPmxxZSUMUJ3SCbCXaL8uEE/8hNf3+7TkQ68UGaXk0iF0THopAwAkD2+HCi882eE/ZEV0tevIckv/f7sGszNhIU9JPXdZ61fU7RVGcMTQrxKe8Ev0Z2p5u6TKLivGqF8D0g0Gn4UMCF+d7B59LMfkIjmyTVeuWrw2UqSr2U0jWJWnNg5ggsy/YVeCdHTWCl9gnIogQLq9RX2wkDnsfDcFJx9ANquLY6nsNBCvukPipFsvaZgaPo+B/y6HFoLYhXOIiT2JiHhVFST5GoyQ5wpZfEnty/glB8Wug/+p71U88Hd9ESUJftH2jWYtAOENUaNhhBQtEBH5Njkv1dAWC4scJBF8bvbii3zD8S62YxvYsfKtHV7lV3HQ8eLr5ut0Ml+REQYpvE8xxDDhJs+ZiqXkof4I/lg8emiUUOZNGSWuuRE2fvYI17refJ42UM1sK8Fs6I3gl9wtKTr2rBxlXVzRnMiDKaLXq3h6MjAHXqNgqCvYWtZslQcBfjOvfHj3rz1dCR6pOgba23MDEE5xbjtaF33DZ6jmfWdtXHeodblhLfnhIETuMokpKq8Wgau4C4JIzy5JlQnAFcJx L5EPcdWN 5Oorn+wDLHw/FEVmqwgdMurP1gLRgWXxzjpJlZ6vtY1bfTUvC1xrRuydrho2ym65M+P8k7WLYudfNsUpDTeuB2Yqj5PKRzVuQTK1O0vMg9NKqu4qgxDNTbTolDUrHNmEf067fThC4zWCeGjKas2XBrPBCL8MzuFr6Z1UBTA+e0dG2EihVan58NBS0bhnV+AxFEiLb 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: On Tue, Mar 28, 2023 at 02:44:27PM -0700, Yosry Ahmed wrote: > > Your swap descriptor will be using one swp_entry_t, which get from the PTE > > to lookup, right? That is the swap entry I am talking about. You just > > substitute zswap swap entry with the swap descriptor swap entry. > > You still need to allocate from the free swap entry space at least once. > > Oh, you mean the swap ID space. We just need to find an unused ID, we > can simply use an allocating xarray > (https://docs.kernel.org/core-api/xarray.html#allocating-xarrays). > This is simpler than keeping track of swap slots in a swapfile. Ah I see. That makes sense. Thanks for explaining it to me. The real block swap device will still need to scan the swap_map to find an empty space to write the page. Chris