Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751372AbWEIW5k (ORCPT ); Tue, 9 May 2006 18:57:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751390AbWEIW5k (ORCPT ); Tue, 9 May 2006 18:57:40 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:42732 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S1751372AbWEIW5k (ORCPT ); Tue, 9 May 2006 18:57:40 -0400 Date: Tue, 9 May 2006 15:56:59 -0700 (PDT) From: Christoph Lameter To: Chris Wright cc: linux-kernel@vger.kernel.org, virtualization@lists.osdl.org, xen-devel@lists.xensource.com, Ian Pratt , Christian Limpach Subject: Re: [RFC PATCH 05/35] Add sync bitops In-Reply-To: <20060509085149.024456000@sous-sol.org> Message-ID: References: <20060509084945.373541000@sous-sol.org> <20060509085149.024456000@sous-sol.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: 689 Lines: 15 On Tue, 9 May 2006, Chris Wright wrote: > Add "always lock'd" implementations of set_bit, clear_bit and > change_bit and the corresponding test_and_ functions. Also add > "always lock'd" implementation of cmpxchg. These give guaranteed > strong synchronisation and are required for non-SMP kernels running on > an SMP hypervisor. Could you explain why this is done and what is exactly meant with "always looked"? Wh the performance impact? - 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/