Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263932AbUDFR51 (ORCPT ); Tue, 6 Apr 2004 13:57:27 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263937AbUDFR51 (ORCPT ); Tue, 6 Apr 2004 13:57:27 -0400 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:11147 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S263932AbUDFR5Y (ORCPT ); Tue, 6 Apr 2004 13:57:24 -0400 Date: Tue, 6 Apr 2004 19:57:22 +0200 From: Andrea Arcangeli To: Ingo Molnar Cc: Eric Whiting , akpm@osdl.org, linux-kernel@vger.kernel.org, Pete Zaitcev Subject: Re: -mmX 4G patches feedback [numbers: how much performance impact] Message-ID: <20040406175722.GE2234@dualathlon.random> References: <40718B2A.967D9467@amis.com> <20040405174616.GH2234@dualathlon.random> <4071D11B.1FEFD20A@amis.com> <20040405221641.GN2234@dualathlon.random> <20040406115539.GA31465@elte.hu> <20040406155925.GW2234@dualathlon.random> <20040406172431.GA9185@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040406172431.GA9185@elte.hu> User-Agent: Mutt/1.4.1i X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1499 Lines: 31 On Tue, Apr 06, 2004 at 07:24:31PM +0200, Ingo Molnar wrote: > (anyway, feel free to reproduce and post contrary results here. The onus I will run benchmarks as soon as I'm back from vacations. You didn't post the modified benchmarks to produce any realistic load. I will use the HINT to measure the slowdown on HZ=1000. It's an optimal benchmark simulating userspace load at various cache sizes and it's somewhat realistic. Note also that the slowdown I expect wasn't of the order 10%, obviously, I was expecting something between 1 and 2% which would be an *huge* slowdown for any cpu bound app just for the timer irq, and I will try to reproduce it on my 4-way xeon. Regardless, even if HZ=1000 would run 1% faster (not 0.02% slower as you measured) that changes nothing in terms of the 4:4 badness, the real badness is for apps doing more than userspace pure calculations. > is on you. And if you think i'm upset about your approach to this whole > issue then you are damn right.) the one upset should be the users running 30% slower with stuff like mysql just because they own a 4/8G box. There's little interest from my part to spend time on 4:4 stuff when things are so obvious (I want however to try to benchmark the HZ=1000 with the hint). - 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/