Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031238AbWI0XUX (ORCPT ); Wed, 27 Sep 2006 19:20:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031245AbWI0XUW (ORCPT ); Wed, 27 Sep 2006 19:20:22 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:54470 "EHLO e36.co.us.ibm.com") by vger.kernel.org with ESMTP id S1031238AbWI0XUV (ORCPT ); Wed, 27 Sep 2006 19:20:21 -0400 Subject: Re: [RFC] exponential update_wall_time From: john stultz To: Andrew Morton Cc: Roman Zippel , lkml , Ingo Molnar , Thomas Gleixner In-Reply-To: <20060927150501.3d40e11e.akpm@osdl.org> References: <1159385734.29040.9.camel@localhost> <20060927150501.3d40e11e.akpm@osdl.org> Content-Type: text/plain Date: Wed, 27 Sep 2006 16:20:21 -0700 Message-Id: <1159399221.7297.16.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 864 Lines: 28 On Wed, 2006-09-27 at 15:05 -0700, Andrew Morton wrote: > On Wed, 27 Sep 2006 12:35:33 -0700 > john stultz wrote: > > > + while (offset > clock->cycle_interval << (shift + 1)) > > + shift++; > > hurts my brain. Yea. Its not the most obvious patch, but the complexity is pretty isolated. > I have a vague feeling that this can be done with > something like ffz(~(offset/clock->cycle_interval))+epsilon, but that hurts > my brain too. Agreed. I don't want to obfuscate this code much more. In my opinion, the loop is tightly bounded and not expensive enough to try to optimize. thanks -john - 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/