From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id EAE826B004A for ; Wed, 10 Nov 2010 09:49:19 -0500 (EST) Received: by fxm20 with SMTP id 20so425841fxm.14 for ; Wed, 10 Nov 2010 06:49:17 -0800 (PST) Subject: Re: [PATCH v2]mm/oom-kill: direct hardware access processes should get bonus From: "Figo.zhang" In-Reply-To: References: <1288662213.10103.2.camel@localhost.localdomain> <1289305468.10699.2.camel@localhost.localdomain> Content-Type: text/plain; charset="UTF-8" Date: Wed, 10 Nov 2010 22:48:16 +0800 Message-ID: <1289400496.10699.21.camel@localhost.localdomain> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: lkml , KOSAKI Motohiro , "linux-mm@kvack.org" , Andrew Morton , Linus Torvalds List-ID: On Tue, 2010-11-09 at 13:16 -0800, David Rientjes wrote: > On Tue, 9 Nov 2010, Figo.zhang wrote: > > > > > the victim should not directly access hardware devices like Xorg server, > > because the hardware could be left in an unpredictable state, although > > user-application can set /proc/pid/oom_score_adj to protect it. so i think > > those processes should get 3% bonus for protection. > > > > The logic here is wrong: if killing these tasks can leave hardware in an > unpredictable state (and that state is presumably harmful), then they > should be completely immune from oom killing since you're still leaving > them exposed here to be killed. we let the processes with hardware access get bonus for protection. the goal is not select them to be killed as possible. > > So the question that needs to be answered is: why do these threads deserve > to use 3% more memory (not >4%) than others without getting killed? If > there was some evidence that these threads have a certain quantity of > memory they require as a fundamental attribute of CAP_SYS_RAWIO, then I > have no objection, but that's going to be expressed in a memory quantity > not a percentage as you have here. > > The CAP_SYS_ADMIN heuristic has a background: it is used in the oom killer > because we have used the same 3% in __vm_enough_memory() for a long time > and we want consistency amongst the heuristics. Adding additional bonuses > with arbitrary values like 3% of memory for things like CAP_SYS_RAWIO > makes the heuristic less predictable and moves us back toward the old > heuristic which was almost entirely arbitrary. yes, i think it is be better those processes which be protection maybe divided the badness score by 4, like old heuristic. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org