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Tue, 28 Nov 2023 15:06:06 -0800 (PST) MIME-Version: 1.0 References: <87msv58068.fsf@yhuang6-desk2.ccr.corp.intel.com> <87h6l77wl5.fsf@yhuang6-desk2.ccr.corp.intel.com> <87r0ka64v9.fsf@yhuang6-desk2.ccr.corp.intel.com> In-Reply-To: From: Yosry Ahmed Date: Tue, 28 Nov 2023 15:05:29 -0800 Message-ID: Subject: Re: [PATCH v10] mm: vmscan: try to reclaim swapcache pages if no swap space To: Minchan Kim Cc: Michal Hocko , "Huang, Ying" , Liu Shixin , Yu Zhao , Andrew Morton , Sachin Sant , Johannes Weiner , Kefeng Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 1E0931C0007 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 6gxc1yn1u4icpxwbucwecs6z8up71ziw X-HE-Tag: 1701212767-508821 X-HE-Meta: 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 VNyAarsh JtzGjYruEOOhMZoGPLwSGVS118CVI8pjqXmOdJ6aZlQR+ecub+HdXsbJuPZSCFq84DfWrPeuGnMnDGDKuanRhok+AtRbZrjXDNwT+O1kfnOseJxbDwmRCgctGRMgclXvS22K2gSiOCjapGQRvqO97OZJgAmmvVUqMWg/Qp6rt12iElW+EUA9UlSVonWJr3wAP8Bfm71oskMs8zzh4cVt8RaSbQqHwComraPr3CEQi4xGtrQuoRhCdqQyltqfT1Gz0cM6hdpsTqFwTvMXAlz7vGsdDTXAnbaObiM2rCv3hXBR+J3s6nwDe+FU3xVxy4iuLe/rMcA4dA2qJD+UbOHqc+Bjq9vGwxBw+kvmh 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 Tue, Nov 28, 2023 at 2:45=E2=80=AFPM Minchan Kim wr= ote: > > On Tue, Nov 28, 2023 at 11:16:04AM +0100, Michal Hocko wrote: > > On Tue 28-11-23 09:31:06, Huang, Ying wrote: > > > Michal Hocko writes: > > [...] > > > > Right. On the other hand we could be more aggressive when dropping = the > > > > swapcache. Is there any actual reason why we cannot try to folio_fr= ee_swap > > > > even when mem_cgroup_swap_full =3D=3D F? > > > > > > If there are plenty free space in swap device, why not take advantage= of > > > it? > > > > Maybe a stupid question but what is the advantage of keeping around in > > the swap cache? > > If the page is shared, we avoids addtional IO to bring them back so > swap cache. I think this case is actually necessary for correctness, not just to avoid additional IO. Otherwise subsequent swapins will create new copies of the page, right? > > If the page is still clean on reclaim moment since swap-in, VM doesn't > need to write them out to the swap disk since original data is already > there.