From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3B1BAC43381 for ; Tue, 12 Mar 2019 18:43:27 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E18B7205C9 for ; Tue, 12 Mar 2019 18:43:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="OwoZi4sC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E18B7205C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6ACD98E0003; Tue, 12 Mar 2019 14:43:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 65DEC8E0002; Tue, 12 Mar 2019 14:43:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 54CD38E0003; Tue, 12 Mar 2019 14:43:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by kanga.kvack.org (Postfix) with ESMTP id 386128E0002 for ; Tue, 12 Mar 2019 14:43:26 -0400 (EDT) Received: by mail-io1-f69.google.com with SMTP id n15so2512481ioc.0 for ; Tue, 12 Mar 2019 11:43:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=fo/v7SBqR9Y8HorvRV4qY+qTc74qy6r2ZpOJax4E0b4=; b=OVAKkvvHt01TeojEtfpAOugNP7sBTnXagZgCdhkI7RNw9WuKiP39YfmkyzV4AsNB86 fD19x2Xd1SoqgftuoubPE+vnufmSs8Hn0puz5mKMnEdt8b/0/nPkbsRepmPgeEnFTtk4 /M92m4udNeR/mpHvYGhnWoJT2//JekQO36jsm2ET9w98eYEd9HuMQ7jREycWbTShwCiC G/YUghLo2XxO1Dkm0zMDwSa7SiS5N/jSbEoVaeDqlOMLfJNZwdAFiqN6ws66TErVwmGn 3R6jvPRHlLHLNr3bVdsn+HYxPccXrPKLvPuGRhqxO/VHJ0NM9zCzEmuHn9c2GdrWlFhB g1ng== X-Gm-Message-State: APjAAAUdEuQoVGHsTakvgNq7reK5UP0nnfFGoXWRc/0UXzHyrd4ABPYL JrYZ6W3lk/2o2NsyJuNHDfCbfUuthZ8WiwFsmCoI3YFQ06UIPuHybxW/NWk/tO57xyzN2amD6fp 1kc9QlfJpphjBgA70HApwLHJJ6CAyC37GVGEhOJXKr0kcuSpqrrn2/WYNPjv9i5VCXtwC6nLZ/A je3LRvuVg7GFNH+X+Epc9SL254Ei7vOxtFbjDEEQPKgYcSovh/pGPT2J38BodTsYO6T2/HfUkZl T/1gRuQoJa1WXZppi7kljCOvayUa2DnmVq7Ly6Mv7DInz6tBqiR5eew+UjJfwLYj6zJDgcsQLba ntKR9NCn65SL2JjOyxvO0QRX3HSElZZ2Lb3Dk5mV53OYhuRp8+wgDi503BtW4O+3hfI1I5rnysM H X-Received: by 2002:a5d:984a:: with SMTP id p10mr5567693ios.217.1552416205967; Tue, 12 Mar 2019 11:43:25 -0700 (PDT) X-Received: by 2002:a5d:984a:: with SMTP id p10mr5567671ios.217.1552416205241; Tue, 12 Mar 2019 11:43:25 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1552416205; cv=none; d=google.com; s=arc-20160816; b=HUS7y2D6uWmBpFAkNdRVXZS32Yk5nRlyFQSyEgTMq1m4ecHQ6jBUvIOu2g0Ni2BUl0 Lix7+YlbR4dQurbWlSsshgv5rSRjwcuxY4RHpEDgTJ1FIVhAq2NKGyOg+wXDhVKDf8eG STafoK6YewOIGNadVdu9DxsFoAH8lnEXtYoPgrTmwTNy3+VdaaFKn1y27C2dXPsKEPQb fVJr10LMfvlj/uJDHQehbzVv39Wbcfh2+zgsxmEO4QldBDAwVLLwmZbSHmjntK7+ck+D HFr6XkS1TDbI7bd5Y1hJVTr6WfuJPLYru7jWubTmOscFk2alpfyuw+tYkVnuDuJ0BRad ANZg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=fo/v7SBqR9Y8HorvRV4qY+qTc74qy6r2ZpOJax4E0b4=; b=qW/4UQhO3fp+6IiFs22sF4hEw62fX8hXmHRlYo0GYYh5eDkRv2pTG6Fz6ThAe5UgsE l8a9nOiDwvMo/JCU9PUoQQ87et2OD4oU/moxugnIkKeWdvh8uTzzdsMq6VgCZpSDDSLF YqKwnEg2Rha+I4eHOYSSJH7t6YxFoDCQyHyemZ8c/UssL3044aY63fRp6F6/9LZg0NAX jWCqlz0VFCFf7gNQyXOdWhGznCeOYtjgQ7bTgyRT4oJb1DFlomsOPgUEWbMhDFe10c+q lWx0xsi01weffz57GcGOGKljOtzQRQEWIxi+YeN03Q8VMOP2RiDYMpDJ5F47hKO0UoF6 Dm+A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=OwoZi4sC; spf=pass (google.com: domain of timmurray@google.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=timmurray@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from mail-sor-f41.google.com (mail-sor-f41.google.com. [209.85.220.41]) by mx.google.com with SMTPS id s25sor2387160iol.28.2019.03.12.11.43.25 for (Google Transport Security); Tue, 12 Mar 2019 11:43:25 -0700 (PDT) Received-SPF: pass (google.com: domain of timmurray@google.com designates 209.85.220.41 as permitted sender) client-ip=209.85.220.41; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=OwoZi4sC; spf=pass (google.com: domain of timmurray@google.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=timmurray@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=fo/v7SBqR9Y8HorvRV4qY+qTc74qy6r2ZpOJax4E0b4=; b=OwoZi4sCHLXm6jIB0SrimzodzEpnuPM1ocHav7KTqC/dNINfGz1ZTNNM/Qor4MM/g0 N+4QizOgiWx6nzvYXPvQ/Cv4V0+kOKHlBD849Q6u93IR06hIERUU+zCuFjk+zYBU0hVW +9wA5VDFmCWUJQo4t4/PMQqmEY68hU97RT4cDqmb03LNd8WglTVlQSADJx8bOSlnFh/h IM6esZI0z3TL94uA0L3h1/beuuBxUp2WaMn2DAMWX4EW2ypY0Ylq3Lr8IdGG/Z4WJy+L nTpuBSvtJn5K6TfhDU/Iupb3+Qq+u8M1sDN4xRN4LTInedhd+UXZkbovRG74KnkZKRpC N40A== X-Google-Smtp-Source: APXvYqxl7+sqyVCZd0nlCLusQ7k24/I/mt+5W6Z1PdcID4CmgBm88PBxwF51+PonJKlNy38PiMl+aatep/V5nuxT7XQ= X-Received: by 2002:a5e:db0d:: with SMTP id q13mr425229iop.279.1552416204862; Tue, 12 Mar 2019 11:43:24 -0700 (PDT) MIME-Version: 1.0 References: <20190310203403.27915-1-sultan@kerneltoast.com> <20190311174320.GC5721@dhcp22.suse.cz> <20190311175800.GA5522@sultan-box.localdomain> <20190311204626.GA3119@sultan-box.localdomain> <20190312080532.GE5721@dhcp22.suse.cz> <20190312163741.GA2762@sultan-box.localdomain> <20190312174520.GA9276@sultan-box.localdomain> In-Reply-To: <20190312174520.GA9276@sultan-box.localdomain> From: Tim Murray Date: Tue, 12 Mar 2019 11:43:13 -0700 Message-ID: Subject: Re: [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android To: Sultan Alsawaf Cc: Michal Hocko , Suren Baghdasaryan , Greg Kroah-Hartman , =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Ingo Molnar , Peter Zijlstra , LKML , devel@driverdev.osuosl.org, linux-mm Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Mar 12, 2019 at 10:45 AM Sultan Alsawaf wrote: > > On Tue, Mar 12, 2019 at 10:17:43AM -0700, Tim Murray wrote: > > Knowing whether a SIGKILL'd process has finished reclaiming is as far > > as I know not possible without something like procfds. That's where > > the 100ms timeout in lmkd comes in. lowmemorykiller and lmkd both > > attempt to wait up to 100ms for reclaim to finish by checking for the > > continued existence of the thread that received the SIGKILL, but this > > really means that they wait up to 100ms for the _thread_ to finish, > > which doesn't tell you anything about the memory used by that process. > > If those threads terminate early and lowmemorykiller/lmkd get a signal > > to kill again, then there may be two processes competing for CPU time > > to reclaim memory. That doesn't reclaim any faster and may be an > > unnecessary kill. > > ... > > - offer a way to wait for process termination so lmkd can tell when > > reclaim has finished and know when killing another process is > > appropriate > > Should be pretty easy with something like this: Yeah, that's in the spirit of what I was suggesting, but there are lot of edge cases around how to get that data out efficiently and PID reuse (it's a real issue--often the Android apps that are causing memory pressure are also constantly creating/destroying threads). I believe procfds or a similar mechanism will be a good solution to this.