Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S382379AbUKAXjt (ORCPT ); Mon, 1 Nov 2004 18:39:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268374AbUKAXbs (ORCPT ); Mon, 1 Nov 2004 18:31:48 -0500 Received: from deliver.epitech.net ([163.5.0.25]:50992 "HELO ideliver.epitech.net") by vger.kernel.org with SMTP id S380292AbUKAXBI (ORCPT ); Mon, 1 Nov 2004 18:01:08 -0500 Date: Tue, 2 Nov 2004 00:01:03 +0100 From: Marc Bevand To: dean gaudet Cc: linux-kernel@vger.kernel.org Subject: Re: [rc4-amd64] RC4 optimized for AMD64 Message-ID: <20041101230103.GA656@iah.epita.fr> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 956 Lines: 23 dean gaudet wrote: | | [...] | ack... it's too early on a monday morning -- i misread the documentation. | this ZF assumption is actually defined and portable... still kind of ugly. | how much benefit do you see? When "dec" is placed before "ror", throughput goes up by about 5% on my test system (Opteron 244 rev C0). I don't find it "ugly" because the optimization no intrusive at all (only 1 moved instruction). Concerning the "dec / sub $1" case, it makes absolutely no difference on the Opteron, I just used "dec" because the opcode is 3 bytes length instead of 4. -- Marc Bevand http://www.epita.fr/~bevand_m Computer Science School EPITA - System, Network and Security Dept. - 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/