Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263893AbUILXGj (ORCPT ); Sun, 12 Sep 2004 19:06:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263818AbUILXGi (ORCPT ); Sun, 12 Sep 2004 19:06:38 -0400 Received: from holomorphy.com ([207.189.100.168]:45447 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S263893AbUILXGc (ORCPT ); Sun, 12 Sep 2004 19:06:32 -0400 Date: Sun, 12 Sep 2004 16:06:17 -0700 From: William Lee Irwin III To: Chris Wedgwood Cc: Ingo Molnar , Anton Blanchard , linux-kernel@vger.kernel.org, viro@parcelfarce.linux.theplanet.co.uk Subject: Re: /proc/sys/kernel/pid_max issues Message-ID: <20040912230617.GS2660@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Chris Wedgwood , Ingo Molnar , Anton Blanchard , linux-kernel@vger.kernel.org, viro@parcelfarce.linux.theplanet.co.uk References: <20040912085609.GK32755@krispykreme> <20040912093605.GJ2660@holomorphy.com> <20040912095805.GL2660@holomorphy.com> <20040912101350.GA13164@elte.hu> <20040912104314.GN2660@holomorphy.com> <20040912104524.GO2660@holomorphy.com> <20040912110810.GQ2660@holomorphy.com> <20040912112026.GA16678@elte.hu> <20040912171319.GR2660@holomorphy.com> <20040912180229.GA7157@taniwha.stupidest.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040912180229.GA7157@taniwha.stupidest.org> Organization: The Domain of Holomorphy User-Agent: Mutt/1.5.6+20040722i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1563 Lines: 29 On Sun, Sep 12, 2004 at 10:13:19AM -0700, William Lee Irwin III wrote: >> I presumed it was merely cosmetic, so daemons around system startup >> will get low pid numbers recognizable by sysadmins. Maybe filtering >> process listings for pids < 300 is/was used to find daemons that may >> have crashed? I'm not particularly attached to the feature, and have >> never used it myself, but merely noticed its implementation was off. On Sun, Sep 12, 2004 at 11:02:29AM -0700, Chris Wedgwood wrote: > I always assumed it was an optimization when looking for a new PID > after a wrap by trying to skip over the kernel threads. Arguably 300 > is way too small for larger systems (which might have several thousand > kernel threads) and should probably be sized on boot (or when starting > userspace) if anyone really cares. There's no reason it couldn't be made tunable, though we may want to place restrictions on what values are allowed, e.g. reserved_pids > 0 and reserved_pids < min(BITS_PER_PAGE, pid_max). For that matter, we should likely be using proc_dointvec_minmax() for pid_max or otherwise a custom strategy function if we need to update bounds on reserved_pids and/or reserved_pids in tandem. I suspect this is obscure enough I should leave it alone unless someone develops a strong opinion about it. -- wli - 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/