From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756812AbYF3OsU (ORCPT ); Mon, 30 Jun 2008 10:48:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751669AbYF3OsJ (ORCPT ); Mon, 30 Jun 2008 10:48:09 -0400 Received: from sinclair.provo.novell.com ([137.65.248.137]:45152 "EHLO sinclair.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751331AbYF3OsI convert rfc822-to-8bit (ORCPT ); Mon, 30 Jun 2008 10:48:08 -0400 Message-Id: <4868B841.BA47.005A.0@novell.com> X-Mailer: Novell GroupWise Internet Agent 7.0.3 Date: Mon, 30 Jun 2008 08:41:05 -0600 From: "Gregory Haskins" To: "Ingo Molnar" Cc: , , , , Subject: Re: [PATCH 0/3] sched: newidle and RT wake-buddy fixes References: <20080627202444.3829.21595.stgit@lsg.lsg.lab.novell.com> <20080630131511.GA7506@elte.hu> In-Reply-To: <20080630131511.GA7506@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On Mon, Jun 30, 2008 at 9:15 AM, in message <20080630131511.GA7506@elte.hu>, Ingo Molnar wrote: > * Gregory Haskins wrote: > >> Hi Ingo, >> The following patches apply to linux-tip/sched/devel and enhance the >> performance of the kernel (specifically in PREEMPT_RT, though they do >> not regress mainline performance as far as I can tell). They offer >> somewhere between 50-100% speedups in netperf performance, depending >> on the test. > > -tip testing found this boot hang: Ok, I dug in a little bit here. I haven't verified this out yet, but I think the problem is that your config is PREEMPT_VOLUNTARY which NOPs the preempt_disable() in schedule() that I rely on to allow the lock to be dropped. (Doh!) One way I can fix this is to fixup the newidle() code to only play the irq dropping tricks ifdef CONFIG_PREEMPT == TRUE. Does this sound reasonable, or is there a better way to address this? -Greg > > Linux version 2.6.26-rc8-tip (mingo@dione) (gcc version 4.2.3) #12917 > SMP Mon Jun 30 15:06:32 CEST 2008 > [...] > CPU 1/1 -> Node 0 > CPU: Physical Processor ID: 0 > CPU: Processor Core ID: 1 > CPU1: AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ stepping 02 > Brought up 2 CPUs > Total of 2 processors activated (8041.15 BogoMIPS). > [ hard hang ] > > with this config: > > http://redhat.com/~mingo/misc/config-Mon_Jun_30_14_54_19_CEST_2008.bad > > full bootlog: > > http://redhat.com/~mingo/misc/hang-Mon_Jun_30_14_54_19_CEST_2008.bad > > it should continue with this bootup sequence: > > calling net_ns_init+0x0/0x1a0 > net_namespace: 376 bytes > initcall net_ns_init+0x0/0x1a0 returned 0 after 0 msecs > calling init_smp_flush+0x0/0x60 > > i've bisected it down to: > > -------------- > | commit cc8160c56843201891766660e3816d2e546c1b17 > | Author: Gregory Haskins > | Date: Fri Jun 27 14:29:50 2008 -0600 > | > | sched: enable interrupts and drop rq-lock during newidle balancing > -------------- > > so i've reverted that change for now. > > Ingo