Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 18 Sep 2002 12:50:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 18 Sep 2002 12:49:35 -0400 Received: from neon-gw-l3.transmeta.com ([63.209.4.196]:34576 "EHLO neon-gw.transmeta.com") by vger.kernel.org with ESMTP id ; Wed, 18 Sep 2002 12:48:48 -0400 Date: Wed, 18 Sep 2002 09:53:59 -0700 (PDT) From: Linus Torvalds To: Rik van Riel 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: 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: 1235 Lines: 35 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 ? > > And are you willing to walk 100000 threads for every 16 pids allocated ? Give me a real-life case where that happens, and I might care. I dare you. 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. And guys, if this is a performance problem for some extreme site, the fix is truly trivial: echo $((0x7fffffff)) > /proc/sys/max_pid and you're done. You're completely making up a problem that is not a problem in real life. Come back to me when the above doesn't work _in_practice_ and somebody is actually bitten, and maybe I'll care. Until then, all you're doing is mental masturbation. Linus - 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/