From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f200.google.com (mail-pf1-f200.google.com [209.85.210.200]) by kanga.kvack.org (Postfix) with ESMTP id 19A818E0001 for ; Mon, 7 Jan 2019 00:10:25 -0500 (EST) Received: by mail-pf1-f200.google.com with SMTP id q63so42420860pfi.19 for ; Sun, 06 Jan 2019 21:10:25 -0800 (PST) Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id az5sor35455810plb.11.2019.01.06.21.10.23 for (Google Transport Security); Sun, 06 Jan 2019 21:10:23 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\)) Subject: Re: memory cgroup pagecache and inode problem From: Fam Zheng In-Reply-To: Date: Mon, 7 Jan 2019 13:10:17 +0800 Content-Transfer-Encoding: quoted-printable Message-Id: References: <15614FDC-198E-449B-BFAF-B00D6EF61155@bytedance.com> <97A4C2CA-97BA-46DB-964A-E44410BB1730@bytedance.com> Sender: owner-linux-mm@kvack.org List-ID: To: Yang Shi Cc: Fam Zheng , cgroups@vger.kernel.org, Linux MM , tj@kernel.org, Johannes Weiner , lizefan@huawei.com, Michal Hocko , Vladimir Davydov , duanxiongchun@bytedance.com, =?utf-8?B?5byg5rC46IKD?= , liuxiaozhou@bytedance.com > On Jan 5, 2019, at 03:36, Yang Shi wrote: >=20 >=20 > drop_caches would drop all page caches globally. You may not want to > drop the page caches used by other memcgs. We=E2=80=99ve tried your async force_empty patch (with a modification to = default it to true to make it transparently enabled for the sake of = testing), and for the past few days the stale mem cgroups still = accumulate, up to 40k. We=E2=80=99ve double checked that the force_empty routines are invoked = when a mem cgroup is offlined. But this doesn=E2=80=99t look very = effective so far. Because, once we do `echo 1 > = /proc/sys/vm/drop_caches`, all the groups immediately go away. This is a bit unexpected. Yang, could you hint what are missing in the force_empty operation, = compared to a blanket drop cache? Fam=