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[73.219.103.14]) by smtp.gmail.com with ESMTPSA id v23-20020ae9e317000000b0069ea555b54dsm532576qkf.128.2022.04.19.14.10.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Apr 2022 14:10:57 -0700 (PDT) Date: Tue, 19 Apr 2022 17:10:55 -0400 From: Kent Overstreet To: Roman Gushchin Cc: linux-mm@kvack.org, Andrew Morton , Dave Chinner , linux-kernel@vger.kernel.org, Johannes Weiner , Michal Hocko , Shakeel Butt , Yang Shi , Greg Kroah-Hartman Subject: Re: [PATCH rfc 0/5] mm: introduce shrinker sysfs interface Message-ID: <20220419211055.jtzfvqagsiwrco6r@moria.home.lan> References: <20220416002756.4087977-1-roman.gushchin@linux.dev> <20220419183654.axbxcjehs6fpqg4z@moria.home.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 78F2D4000D X-Stat-Signature: 655q763n1g4c7h379smmzsr6wf11akc7 Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=n+9QqXc3; spf=pass (imf11.hostedemail.com: domain of kent.overstreet@gmail.com designates 209.85.222.179 as permitted sender) smtp.mailfrom=kent.overstreet@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1650402657-800268 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, Apr 19, 2022 at 11:50:45AM -0700, Roman Gushchin wrote: > On Tue, Apr 19, 2022 at 02:36:54PM -0400, Kent Overstreet wrote: > > On Fri, Apr 15, 2022 at 05:27:51PM -0700, Roman Gushchin wrote: > > > 7) Don't display cgroups with less than 500 attached objects > > > $ echo 500 > count_memcg > > > $ cat count_memcg > > > 53 817 > > > 1868 886 > > > 2396 799 > > > 2462 861 > > > > > > 8) Don't display cgroups with less than 500 attached objects (sum over all nodes) > > > $ echo "500" > count_memcg_node > > > $ cat count_memcg_node > > > 53 810 7 > > > 1868 886 0 > > > 2396 799 0 > > > 2462 861 0 > > > > > > 9) Scan system/root shrinker > > > $ cat count > > > 212 > > > $ echo 100 > scan > > > $ cat scan > > > 97 > > > $ cat count > > > 115 > > > > This part seems entirely overengineered though and a really bad idea - can we > > please _not_ store query state in the kernel? It's not thread safe, and it seems > > like overengineering before we've done the basics (just getting this stuff in > > sysfs is a major improvement!). > > Yes, it's not great, but I don't have a better idea yet. How to return the number > of freed objects? Do you suggest to drop this functionality at all or there are > other options I'm not seeing? I'd just drop all of the stateful stuff - or add an ioctl interface.