Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753208AbZFOEbR (ORCPT ); Mon, 15 Jun 2009 00:31:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750913AbZFOEbD (ORCPT ); Mon, 15 Jun 2009 00:31:03 -0400 Received: from bilbo.ozlabs.org ([203.10.76.25]:42183 "EHLO bilbo.ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750891AbZFOEbC (ORCPT ); Mon, 15 Jun 2009 00:31:02 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18997.52863.576426.501025@cargo.ozlabs.ibm.com> Date: Mon, 15 Jun 2009 14:30:55 +1000 From: Paul Mackerras To: Roland Dreier Cc: Avi Kivity , Linus Torvalds , benh@kernel.crashing.org, akpm@linux-foundation.org, linuxppc-dev@ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] lib: Provide generic atomic64_t implementation In-Reply-To: References: <18995.20685.227683.561827@cargo.ozlabs.ibm.com> <4A34E4A5.3040306@redhat.com> <18996.60235.178618.531664@cargo.ozlabs.ibm.com> <4A34F564.2010500@redhat.com> X-Mailer: VM 8.0.12 under 22.2.1 (i486-pc-linux-gnu) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 878 Lines: 21 Roland Dreier writes: > FWIW, Nehalem EX actually goes to 8 cores/16 threads per socket. But > worrying about 32-bit performance on Nehalem is a little silly -- this > simplest solution is simply to run a 64-bit kernel. I'm not worried about ANY x86 processor, 32-bit or 64-bit, in fact, since x86 already has an atomic64_t implementation for both 32-bit and 64-bit. It is interesting, though, that arch/x86/include/asm/atomic_32.h unconditionally uses cmpxchg8b to implement atomic64_t, but I thought that cmpxchg8b didn't exist in processors prior to the Pentium. Presumably you can't use perf_counters on a 386 or 486. Paul. -- 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/