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[73.219.103.14]) by smtp.gmail.com with ESMTPSA id m139-20020a37a391000000b0069e88edfdacsm375265qke.105.2022.04.19.11.36.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Apr 2022 11:36:56 -0700 (PDT) Date: Tue, 19 Apr 2022 14:36:54 -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: <20220419183654.axbxcjehs6fpqg4z@moria.home.lan> References: <20220416002756.4087977-1-roman.gushchin@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220416002756.4087977-1-roman.gushchin@linux.dev> Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=pUNRUP0C; spf=pass (imf29.hostedemail.com: domain of kent.overstreet@gmail.com designates 209.85.160.182 as permitted sender) smtp.mailfrom=kent.overstreet@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Stat-Signature: x4mkgguoyce19437fguwk6mkqbo8btbu X-Rspamd-Queue-Id: 74748120010 X-Rspamd-Server: rspam04 X-Rspam-User: X-HE-Tag: 1650393417-804303 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 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!). I know kmemleak does something kinda sorta like this, but that's a special purpose debugging tool and this looks to be something more general purpose that'll get used in production.