From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752316AbXDMGzd (ORCPT ); Fri, 13 Apr 2007 02:55:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752310AbXDMGzd (ORCPT ); Fri, 13 Apr 2007 02:55:33 -0400 Received: from holomorphy.com ([66.93.40.71]:37373 "EHLO holomorphy.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752068AbXDMGzc (ORCPT ); Fri, 13 Apr 2007 02:55:32 -0400 Date: Thu, 12 Apr 2007 23:55:45 -0700 From: William Lee Irwin III To: Nick Piggin Cc: Andrew Morton , Matt Mackall , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/13] maps: pagemap, kpagemap, and related cleanups Message-ID: <20070413065545.GQ2986@holomorphy.com> References: <20070412163235.dd030637.akpm@linux-foundation.org> <461ECB9C.8060000@yahoo.com.au> <20070412174201.065068b2.akpm@linux-foundation.org> <461ED96C.5030606@yahoo.com.au> <20070412182213.a18cc4a7.akpm@linux-foundation.org> <461EE005.6070605@yahoo.com.au> <20070412185723.5a5f0443.akpm@linux-foundation.org> <461EE890.2040601@yahoo.com.au> <20070412193255.62a0b8ed.akpm@linux-foundation.org> <461EFB98.8050408@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <461EFB98.8050408@yahoo.com.au> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: >> Do a full pagetable walk, with all the associated locking from within >> a systemtap script? I'd be surprised. Maybe if it's mostly hand-coded >> in C, perhaps. Then you just end up with the same thing, don't you? On Fri, Apr 13, 2007 at 01:40:08PM +1000, Nick Piggin wrote: > And my problem isn't with the hardcoded pagetable walker. Yeah, we'd > probably still keep the pagetable callback walker thingy with Matt's > associated cleanups (and my subsequent ones to clean it up more and > move it to mm/): there are other in-kernel users for that anyway. > The point is the proc API, and exposing random little parts of deep > kernel internals that some people happen to find useful at the time. > (which is why we have an incredible proliferation of these things). > With systemtap scripts, you could walk pagetables and print *the exact > page information you want*, or you could walk pfns, or LRU, or page_tree, > or walk the page tree then the rmap structures. And you can selectively > cull out items you don't care about if you only care about a subset of > items, based on arbitrary criteria. And you can most likely do all that > more efficiently than with a conglomeration of various /proc files > (assuming they even provide what you want in the first place). The EM guys are unwilling or unable for support-oriented reasons to deal with anything but unmodified kernels as shipped by distros. -- wli