From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756740Ab1LBOpp (ORCPT ); Fri, 2 Dec 2011 09:45:45 -0500 Received: from relay1.mentorg.com ([192.94.38.131]:43747 "EHLO relay1.mentorg.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756656Ab1LBOpn (ORCPT ); Fri, 2 Dec 2011 09:45:43 -0500 From: Pedro Alves Organization: CodeSourcery To: Pavel Emelyanov Subject: Re: [rfc 2/3] fs, proc: Introduce the Children: line in /proc//status Date: Fri, 2 Dec 2011 14:45:36 +0000 User-Agent: KMail/1.13.6 (Linux/2.6.38-13-generic; KDE/4.7.2; x86_64; ; ) Cc: KAMEZAWA Hiroyuki , Cyrill Gorcunov , "linux-kernel@vger.kernel.org" , Andrew Morton , Tejun Heo , Andrew Vagin , Serge Hallyn , Vasiliy Kulikov References: <20111129191252.769160532@openvz.org> <201112021425.44897.pedro@codesourcery.com> <4ED8E296.3070005@parallels.com> In-Reply-To: <4ED8E296.3070005@parallels.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201112021445.37024.pedro@codesourcery.com> X-OriginalArrivalTime: 02 Dec 2011 14:45:39.0480 (UTC) FILETIME=[0F302980:01CCB101] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Friday 02 December 2011 14:37:10, Pavel Emelyanov wrote: > On 12/02/2011 06:25 PM, Pedro Alves wrote: > > On Friday 02 December 2011 14:17:08, Pavel Emelyanov wrote: > > > >> O_O OK, I was wrong, they do live there. But I consider this as bug. > > > > You can't change that. It'd break current gdb at least. > > OMG! You know, NPTL didn't exist on earlier kernels. This preserved backwards compatibility. > >> I.e. each task will be shown multiple times, which is not very fun, but memory exhaustive from my POV. > > > > Now that is a good argument against hard linking. But not if you make > > the entries under children/ symlinks. Then find doesn't recurse. And > > then > > > > $ find -L /proc/PID/ > > > > does recurse and give you the whole tree. Which I'd say is > > actually useful... > > It is useful, but the /proc/pid/children file solves the same problem in a much > more simple way. The memory usage by proc (one file vs one dir and a set of files) > is less and time to lookup a child is also less (read + lookup vs readdir + lookup > (symlink itself) + lookup (symlink resolve)). > > Yes, it doesn't allow you to have fun with find, but frankly, do you really need > this? Even if we're talking about gdb -- reading /proc/pid/children is not harder > and not easier than readdir-ing it. > > IOW - what's the real benefit of a directory with symlinks against a file except > for a fun? As I said on the first message, it's easier on the command line, likely for quick scripting too. And for consistency. gdb or whatever other software can of course do whatever programatically. But if I can't persuade you guys that's a good thing, fine. -- Pedro Alves