Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753735AbYHMQJg (ORCPT ); Wed, 13 Aug 2008 12:09:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751352AbYHMQJ2 (ORCPT ); Wed, 13 Aug 2008 12:09:28 -0400 Received: from terminus.zytor.com ([198.137.202.10]:42521 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751116AbYHMQJ2 (ORCPT ); Wed, 13 Aug 2008 12:09:28 -0400 Message-ID: <48A30642.4060709@zytor.com> Date: Wed, 13 Aug 2008 09:05:22 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Ulrich Drepper CC: Ingo Molnar , Arjan van de Ven , akpm@linux-foundation.org, hugh@veritas.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, briangrant@google.com, cgd@google.com, mbligh@google.com, Linus Torvalds , Thomas Gleixner Subject: Re: pthread_create() slow for many threads; also time to revisit 64b context switch optimization? References: <20080813104445.GA24632@elte.hu> <20080813063533.444c650d@infradead.org> <48A2EE07.3040003@redhat.com> <20080813142529.GB21129@elte.hu> <48A2F157.7000303@redhat.com> <20080813151007.GA8780@elte.hu> <48A2FC17.9070302@redhat.com> In-Reply-To: <48A2FC17.9070302@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1168 Lines: 28 Ulrich Drepper wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Ingo Molnar wrote: >> i find it pretty unacceptable these days that we limit any aspect of >> pure 64-bit apps in any way to 4GB (or any other 32-bit-ish limit). > > Sure, but if we can pin-point the sub-archs for which it is the problem > then a flag to optionally request it is even easier to handle. You'd > simply ignore the flag for anything but the P4 architecture. > > I personally have no problem removing the whole thing because I have no > such machine running anymore. But there are people out there who have. > This could also be done entirely in glibc (thus removing the dependency on the kernel): set the flag if and only if you detect a P4 CPU. You don't even need to enumerate all the CPUs in the system (which would be more painful) if you make the CPUID test wide enough that it catches all compatible CPUs. -hpa -- 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/