Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264365AbUAaClH (ORCPT ); Fri, 30 Jan 2004 21:41:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264457AbUAaClH (ORCPT ); Fri, 30 Jan 2004 21:41:07 -0500 Received: from mail.shareable.org ([81.29.64.88]:41344 "EHLO mail.shareable.org") by vger.kernel.org with ESMTP id S264365AbUAaClF (ORCPT ); Fri, 30 Jan 2004 21:41:05 -0500 Date: Sat, 31 Jan 2004 02:41:00 +0000 From: Jamie Lokier To: "Eric W. Biederman" Cc: Ulrich Drepper , john stultz , lkml Subject: Re: [RFC][PATCH] linux-2.6.2-rc2_vsyscall-gtod_B1.patch Message-ID: <20040131024100.GA9236@mail.shareable.org> References: <1075344395.1592.87.camel@cog.beaverton.ibm.com> <401894DA.7000609@redhat.com> <20040129132623.GB13225@mail.shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 712 Lines: 16 Eric W. Biederman wrote: > With the x86-64 optimized vsyscall the syscall number does > not need to be placed into a register, because you have used > the proper entry point. For any syscall worth tuning in > user space I suspect that level of optimization would be > beneficial. A fast call path that does not waste a register. The cost of loading a constant into a register is _much_ lower than the cost of indirect jumps which we have been discussing. -- Jamie - 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/