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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 96859C43381 for ; Tue, 12 Mar 2019 15:33:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61CBD2083D for ; Tue, 12 Mar 2019 15:33:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1552404801; bh=ves5n6enpL+5V+AhpnpZHtzyJiCyHPWClcAOzEJHRhw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=TrGiPze5+Pv4EhGW3YsjA/x5SrairMcO0NXUnt8jXpnol5uPh9eHOvz6xziqkVFlw ukZNXAfu+0SGvHwzdDmsai7/N2nn40Kv90q6IBqLSjqz/pQZYaSwqpxE00Gjpl+778 sYzcyxFbVw1IYWWbLgCwxgieayHCDVamARFPUIZk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726890AbfCLPdU (ORCPT ); Tue, 12 Mar 2019 11:33:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:44094 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726422AbfCLPdT (ORCPT ); Tue, 12 Mar 2019 11:33:19 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 35CC6B69E; Tue, 12 Mar 2019 15:33:17 +0000 (UTC) Date: Tue, 12 Mar 2019 16:33:15 +0100 From: Michal Hocko To: Matthew Wilcox Cc: Suren Baghdasaryan , Sultan Alsawaf , Greg Kroah-Hartman , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Ingo Molnar , Peter Zijlstra , LKML , devel@driverdev.osuosl.org, linux-mm , Tim Murray Subject: Re: [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android Message-ID: <20190312153315.GV5721@dhcp22.suse.cz> 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> <20190312152541.GI19508@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190312152541.GI19508@bombadil.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 12-03-19 08:25:41, Matthew Wilcox wrote: > On Tue, Mar 12, 2019 at 09:05:32AM +0100, Michal Hocko wrote: > > On Mon 11-03-19 15:15:35, Suren Baghdasaryan wrote: > > > Yeah, killing speed is a well-known problem which we are considering > > > in LMKD. For example the recent LMKD change to assign process being > > > killed to a cpuset cgroup containing big cores cuts the kill time > > > considerably. This is not ideal and we are thinking about better ways > > > to expedite the cleanup process. > > > > If you design is relies on the speed of killing then it is fundamentally > > flawed AFAICT. You cannot assume anything about how quickly a task dies. > > It might be blocked in an uninterruptible sleep or performin an > > operation which takes some time. Sure, oom_reaper might help here but > > still. > > Many UNINTERRUPTIBLE sleeps can be converted to KILLABLE sleeps. It just > needs someone to do the work. They can and should as much as possible. No question about that. But not all of them can and that is why nobody should be relying on that. That is the whole point of having the oom_reaper and async oom victim tear down. -- Michal Hocko SUSE Labs