From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752310AbXDMHDv (ORCPT ); Fri, 13 Apr 2007 03:03:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752318AbXDMHDv (ORCPT ); Fri, 13 Apr 2007 03:03:51 -0400 Received: from smtp105.mail.mud.yahoo.com ([209.191.85.215]:40263 "HELO smtp105.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752264AbXDMHDv (ORCPT ); Fri, 13 Apr 2007 03:03:51 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=g7BbJY7iHyuJiKBsNQL71Rm1ap9ZL6btFjlDBF2Ywjn/esIvUBlMTlBaTzb9B1Bf0e9marP7T+rlVIlPHD29PQj9kjLRBV332X/XzwSsuzIO2ehszUjCt/0rOwWpXrwkvQKP6OcIy++VvliSVrZQuSPnehQFZ+TBNq1TAJ/K9po= ; X-YMail-OSG: yLjcabgVM1nd7QREJ5RUhTq3XkAcuJtiygoO4MLiyM0TNi49LYnbD0bAB00xjFq_9FAZeQUhYQ-- Message-ID: <461F2B4F.90506@yahoo.com.au> Date: Fri, 13 Apr 2007 17:03:43 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: William Lee Irwin III CC: Andrew Morton , Matt Mackall , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/13] maps: pagemap, kpagemap, and related cleanups 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> <20070413065545.GQ2986@holomorphy.com> In-Reply-To: <20070413065545.GQ2986@holomorphy.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org William Lee Irwin III wrote: > 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. And I think major distros ship with kprobes enabled, so that is yet another reason why systemtap should be considered before adding these proc interfaces. Thanks, Nick -- SUSE Labs, Novell Inc.