Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161139AbXAZSXv (ORCPT ); Fri, 26 Jan 2007 13:23:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161149AbXAZSXu (ORCPT ); Fri, 26 Jan 2007 13:23:50 -0500 Received: from omx1-ext.sgi.com ([192.48.179.11]:34680 "EHLO omx1.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1161139AbXAZSXt (ORCPT ); Fri, 26 Jan 2007 13:23:49 -0500 Date: Fri, 26 Jan 2007 10:23:44 -0800 (PST) From: Christoph Lameter To: Andrew Morton cc: Nick Piggin , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC] Track mlock()ed pages In-Reply-To: <20070126101027.90bf3e63.akpm@osdl.org> Message-ID: References: <45B9A00C.4040701@yahoo.com.au> <20070126031300.59f75b06.akpm@osdl.org> <20070126101027.90bf3e63.akpm@osdl.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1304 Lines: 36 On Fri, 26 Jan 2007, Andrew Morton wrote: > > Large amounts of mlocked pages may be a problem for > > > > 1. Reclaim behavior. > > > > 2. Defragmentation > > > > We know that. What has that to do with this patch? Knowing how much mlocked pages are where is necessary to solve these issues. > > > You could perhaps go for a walk across all the other vmas which presently > > > map this page. If any of them have VM_LOCKED, don't increment the counter. > > > Similar on removal: only decrement the counter when the final mlocked VMA > > > is dropping the pte. > > > > For that we would need an additional refcount for vmlocked maps in the > > page struct. > > No you don't. The refcount is already there. It is "the sum of the VM_LOCKED > VMAs which map this page". > > It might be impractical or expensive to calculate it, but it's there. Correct. Its so expensive that it cannot be used to build vm stats for mlocked pages. F.e. Determination of the final mlocked VMA dropping the page would require a scan over all vmas mapping the page. - 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/