Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932196AbVIXQvw (ORCPT ); Sat, 24 Sep 2005 12:51:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932197AbVIXQvw (ORCPT ); Sat, 24 Sep 2005 12:51:52 -0400 Received: from gateway-1237.mvista.com ([12.44.186.158]:44530 "EHLO av.mvista.com") by vger.kernel.org with ESMTP id S932196AbVIXQvv (ORCPT ); Sat, 24 Sep 2005 12:51:51 -0400 Subject: Re: [ANNOUNCE] ktimers subsystem From: Daniel Walker To: tglx@linutronix.de Cc: Roman Zippel , Ingo Molnar , Christopher Friesen , linux-kernel@vger.kernel.org, akpm@osdl.org, george@mvista.com, johnstul@us.ibm.com, paulmck@us.ibm.com In-Reply-To: <1127570212.15115.77.camel@tglx.tec.linutronix.de> References: <20050919184834.1.patchmail@tglx.tec.linutronix.de> <1127342485.24044.600.camel@tglx.tec.linutronix.de> <43333EBA.5030506@nortel.com> <1127458197.24044.726.camel@tglx.tec.linutronix.de> <20050924051643.GB29052@elte.hu> <1127570212.15115.77.camel@tglx.tec.linutronix.de> Content-Type: text/plain Date: Sat, 24 Sep 2005 09:51:21 -0700 Message-Id: <1127580681.18231.42.camel@c-67-188-6-232.hsd1.ca.comcast.net> Mime-Version: 1.0 X-Mailer: Evolution 2.0.4 (2.0.4-6) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1817 Lines: 43 On Sat, 2005-09-24 at 15:56 +0200, Thomas Gleixner wrote: > On Sat, 2005-09-24 at 12:35 +0200, Roman Zippel wrote: > > Hi, > > > > On Sat, 24 Sep 2005, Ingo Molnar wrote: > > > > > > Anyway, the biggest cost is the conversion from/to the 64bit ns value > > > > [...] > > > > > > Where do you get that notion from? Have you personally measured the > > > performance and code size impact of it? If yes, would you mind to share > > > the resulting data with us? > > > > > > Our data is that the use of 64-bit nsec_t significantly reduces the size > > > of a representative piece of code (object size in bytes): > > > > > > AMD64 I386 ARM PPC32 M68K > > > nsec_t_ops 226 284 252 428 206 > > > timespec_ops 412 324 448 640 342 > > > > > > i.e. a ~40% size reduction when going to nsec_t on m68k, in that > > > particular function. Even larger, ~45% code size reduction on a true > > > 64-bit platform. > > > > Without any source these numbers are not verifiable. You don't even > > mention here what that "representative piece of code" is... These numbers are misleading .. Doing a total code comparison shows that a 2.6.14-rc2+ktimers kernel is slightly bigger than a vanilla 2.6.14-rc2 kernel (gcc 4.0, defconfig) .. So your argument that "small is faster" must mean ktimers is slower, or at least not faster .. Making a speed argument based on code size doesn't make much sense to me, if it's actually faster then show that it's faster. Daniel - 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/