From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 0BD89600385 for ; Fri, 28 May 2010 10:06:32 -0400 (EDT) Received: by pzk37 with SMTP id 37so782017pzk.27 for ; Fri, 28 May 2010 07:06:31 -0700 (PDT) Date: Fri, 28 May 2010 23:06:23 +0900 From: Minchan Kim Subject: Re: [RFC] oom-kill: give the dying task a higher priority Message-ID: <20100528140623.GA11041@barrios-desktop> References: <20100528143605.7E2A.A69D9226@jp.fujitsu.com> <20100528145329.7E2D.A69D9226@jp.fujitsu.com> <20100528125305.GE11364@uudg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100528125305.GE11364@uudg.org> Sender: owner-linux-mm@kvack.org To: "Luis Claudio R. Goncalves" Cc: KOSAKI Motohiro , balbir@linux.vnet.ibm.com, Oleg Nesterov , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Thomas Gleixner , Peter Zijlstra , David Rientjes , Mel Gorman , williams@redhat.com List-ID: On Fri, May 28, 2010 at 09:53:05AM -0300, Luis Claudio R. Goncalves wrote: > On Fri, May 28, 2010 at 02:59:02PM +0900, KOSAKI Motohiro wrote: > | > RT Task > | > > | > void non-RT-function() > | > { > | > system call(); > | > buffer = malloc(); > | > memset(buffer); > | > } > | > /* > | > * We make sure this function must be executed in some millisecond > | > */ > | > void RT-function() > | > { > | > some calculation(); <- This doesn't have no dynamic characteristic > | > } > | > int main() > | > { > | > non-RT-function(); > | > /* This function make sure RT-function cannot preempt by others */ > | > set_RT_max_high_priority(); > | > RT-function A(); > | > set_normal_priority(); > | > non-RT-function(); > | > } > | > > | > We don't want realtime in whole function of the task. What we want is > | > just RT-function A. > | > Of course, current Linux cannot make perfectly sure RT-functionA can > | > not preempt by others. > | > That's because some interrupt or exception happen. But RT-function A > | > doesn't related to any dynamic characteristic. What can justify to > | > preempt RT-function A by other processes? > | > | As far as my observation, RT-function always have some syscall. because pure > | calculation doesn't need deterministic guarantee. But _if_ you are really > | using such priority design. I'm ok maximum NonRT priority instead maximum > | RT priority too. > > I confess I failed to distinguish memcg OOM and system OOM and used "in > case of OOM kill the selected task the faster you can" as the guideline. > If the exit code path is short that shouldn't be a problem. > > Maybe the right way to go would be giving the dying task the biggest > priority inside that memcg to be sure that it will be the next process from > that memcg to be scheduled. Would that be reasonable? Hmm. I can't understand your point. What do you mean failing distinguish memcg and system OOM? We already have been distinguish it by mem_cgroup_out_of_memory. (but we have to enable CONFIG_CGROUP_MEM_RES_CTLR). So task selected in select_bad_process is one out of memcg's tasks when memcg have a memory pressure. Isn't it enough? -- Kind regards, Minchan Kim -- 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/ . Don't email: email@kvack.org