From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id D25286B0083 for ; Thu, 30 Jun 2011 01:11:37 -0400 (EDT) Received: from d28relay03.in.ibm.com (d28relay03.in.ibm.com [9.184.220.60]) by e28smtp01.in.ibm.com (8.14.4/8.13.1) with ESMTP id p5U5BPFe015239 for ; Thu, 30 Jun 2011 10:41:25 +0530 Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay03.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p5U5BPvC3977222 for ; Thu, 30 Jun 2011 10:41:25 +0530 Received: from d28av01.in.ibm.com (loopback [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p5U5BOjd024174 for ; Thu, 30 Jun 2011 10:41:24 +0530 Date: Thu, 30 Jun 2011 10:41:23 +0530 From: Ankita Garg Subject: Re: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management Message-ID: <20110630051123.GD12667@in.ibm.com> Reply-To: Ankita Garg References: <1306499498-14263-1-git-send-email-ankita@in.ibm.com> <20110629130038.GA7909@in.ibm.com> <1309367184.11430.594.camel@nimitz> <20110629174220.GA9152@in.ibm.com> <1309370342.11430.604.camel@nimitz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: Dave Hansen , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-pm@lists.linux-foundation.org, svaidy@linux.vnet.ibm.com, thomas.abraham@linaro.org, "Paul E. McKenney" , KAMEZAWA Hiroyuki , Matthew Garrett , Arjan van de Ven Hi, On Wed, Jun 29, 2011 at 01:11:00PM -0700, Andi Kleen wrote: > Dave Hansen writes: > > > > It's also going to be a pain to track kernel references. On x86, our > As Vaidy mentioned, we are only looking at memory being either allocated or free, as a way to evacuate it. Tracking memory references, no doubt, is a difficult proposition and might involve a lot of overhead. > Even if you tracked them what would you do with them? > > It's quite hard to stop using arbitary kernel memory (see all the dancing > memory-failure does) > > You need to track the direct accesses to user data which happens > to be accessed through the direct mapping. > > Also it will be always unreliable because this all won't track DMA. > For that you would also need to track in the dma_* infrastructure, > which will likely get seriously expensive. > -- Regards, Ankita Garg (ankita@in.ibm.com) Linux Technology Center IBM India Systems & Technology Labs, Bangalore, India -- 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 internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org