From mboxrd@z Thu Jan 1 00:00:00 1970 From: ankita@in.ibm.com (Ankita Garg) Date: Thu, 30 Jun 2011 10:41:23 +0530 Subject: [PATCH 00/10] mm: Linux VM Infrastructure to support Memory Power Management In-Reply-To: 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> Message-ID: <20110630051123.GD12667@in.ibm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 at in.ibm.com) Linux Technology Center IBM India Systems & Technology Labs, Bangalore, India