Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752294AbZK1PfP (ORCPT ); Sat, 28 Nov 2009 10:35:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751937AbZK1PfO (ORCPT ); Sat, 28 Nov 2009 10:35:14 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:59138 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752186AbZK1PfN (ORCPT ); Sat, 28 Nov 2009 10:35:13 -0500 Subject: Re: Problem? intel_iommu=off; perf top shows acpi_os_read_port as extremely busy From: Peter Zijlstra To: Ingo Molnar Cc: Michael Breuer , Thomas Gleixner , Len Brown , Arjan van de Ven , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org In-Reply-To: <20091128071808.GA32183@elte.hu> References: <4B106CC0.4050406@majjas.com> <20091128071808.GA32183@elte.hu> Content-Type: text/plain; charset="UTF-8" Date: Sat, 28 Nov 2009 16:27:46 +0100 Message-ID: <1259422066.2155.4.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1451 Lines: 36 On Sat, 2009-11-28 at 08:18 +0100, Ingo Molnar wrote: > * Michael Breuer wrote: > > > Having given up for now on VT-D, I rebooted 2.6.38 rc8 with > > intel_iommu=off. Whilst my myriad of broken bios issues cleared, I now > > see in perf top acpi_os_read_port as continually the busiest function. > > With intel_iommu enabled, _spin_lock was always on top, and nothing > > else was notable. > > > > This seems odd to me, perhaps this will make sense to someone else. > > > > FWIW, I'm running on an Asus p6t deluxe v2; ht enabled; no errors or > > oddities in dmesg or /var/log/messages. > > Could you post the perf top output please? > > Also, could you also post the output of: > > perf stat -a --repeat 10 sleep 1 > > this will show us how idle the system is. (My guess is that your system > is idle and perf top shows acpi_os_read_port because the system goes to > idle via ACPI methods and PIO is slow. In that case all is nominal and > your system is fine. But it's hard to tell without more details.) Isn't there also a list of symbols it won't display? Can't find either the list nor the switch to turn it off (really didn't look hard), but acme might know. -- 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/