Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752728Ab1F3FLl (ORCPT ); Thu, 30 Jun 2011 01:11:41 -0400 Received: from e28smtp09.in.ibm.com ([122.248.162.9]:42014 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750888Ab1F3FLe (ORCPT ); Thu, 30 Jun 2011 01:11:34 -0400 Date: Thu, 30 Jun 2011 10:41:23 +0530 From: Ankita Garg 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 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: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1238 Lines: 36 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/