Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 18 Sep 2002 12:57:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 18 Sep 2002 12:56:19 -0400 Received: from perninha.conectiva.com.br ([200.250.58.156]:57103 "HELO perninha.conectiva.com.br") by vger.kernel.org with SMTP id ; Wed, 18 Sep 2002 12:55:31 -0400 Date: Wed, 18 Sep 2002 14:00:19 -0300 (BRT) From: Rik van Riel X-X-Sender: riel@duckman.distro.conectiva To: Linus Torvalds Cc: Andries Brouwer , Ingo Molnar , William Lee Irwin III , Subject: Re: [patch] lockless, scalable get_pid(), for_each_process() elimination, 2.5.35-BK In-Reply-To: Message-ID: X-spambait: aardvark@kernelnewbies.org X-spammeplease: aardvark@nl.linux.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: 1091 Lines: 31 On Wed, 18 Sep 2002, Linus Torvalds wrote: > On Wed, 18 Sep 2002, Rik van Riel wrote: > > > > On second thought ... yes there's a reason. Suppose you have > > 100000 threads on your box already, how long is it going to > > take to walk them all to figure out the pid distribution ? > The pid space is not a uniform distribution, which your made-up-example > depends on. So you usually walk the 100000 threads _once_, and then you > don't have to walk them again for quite a long time. Agreed, you're right there. On the other hand, walking the threads _once_ will take 1.5 minutes on a 500 MHz PII (according to Ingo's measurements). That's about 18 times the timeout for the NMI oopser and will cause people real trouble. cheers, Rik -- Spamtrap of the month: september@surriel.com http://www.surriel.com/ http://distro.conectiva.com/ - 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/