Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261381AbVARSbR (ORCPT ); Tue, 18 Jan 2005 13:31:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261379AbVARSbR (ORCPT ); Tue, 18 Jan 2005 13:31:17 -0500 Received: from palrel12.hp.com ([156.153.255.237]:14476 "EHLO palrel12.hp.com") by vger.kernel.org with ESMTP id S261369AbVARSbO (ORCPT ); Tue, 18 Jan 2005 13:31:14 -0500 From: David Mosberger MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16877.21998.984277.551515@napali.hpl.hp.com> Date: Tue, 18 Jan 2005 10:31:10 -0800 To: Linus Torvalds Cc: "Luck, Tony" , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: pipe performance regression on ia64 In-Reply-To: References: <200501181741.j0IHfGf30058@unix-os.sc.intel.com> X-Mailer: VM 7.19 under Emacs 21.3.1 Reply-To: davidm@hpl.hp.com X-URL: http://www.hpl.hp.com/personal/David_Mosberger/ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1007 Lines: 23 >>>>> On Tue, 18 Jan 2005 10:11:26 -0800 (PST), Linus Torvalds said: Linus> I don't know how to make the benchmark look repeatable and Linus> good, though. The CPU affinity thing may be the right thing. Perhaps it should be split up into three cases: - producer/consumer pinned to the same CPU - producer/consumer pinned to different CPUs - producer/consumer lefter under control of the scheduler The first two would let us observe any changes in the actual pipe code, whereas the 3rd case would tell us which case the scheduler is leaning towards (or if it starts doing something real crazy, like reschedule the tasks on different CPUs each time, we'd see a bandwith lower than case 2 and that should ring alarm bells). --david - 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/