From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753198Ab1HAPwK (ORCPT ); Mon, 1 Aug 2011 11:52:10 -0400 Received: from vms173011pub.verizon.net ([206.46.173.11]:35113 "EHLO vms173011pub.verizon.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752832Ab1HAPwB (ORCPT ); Mon, 1 Aug 2011 11:52:01 -0400 X-Greylist: delayed 3605 seconds by postgrey-1.27 at vger.kernel.org; Mon, 01 Aug 2011 11:52:01 EDT Date: Mon, 01 Aug 2011 10:51:38 -0400 (EDT) From: Len Brown X-X-Sender: lenb@x980 To: "Yung, Winson W" Cc: Venkatesh Pallipadi , "linux-kernel@vger.kernel.org" , "Van De Ven, Arjan" , "Kanigeri, Hari K" Subject: RE: [PATCH] [RFC] ondemand governor: dynamic cpufreq scaling with different CPUs In-reply-to: Message-id: References: User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-version: 1.0 Content-type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Re: software vs hardware coordination Speaking for Intel, everything we make, from hand-sets to supercomputers supports hardware coorination. Think about it -- if we did not, then we would not be able to support a legacy OS that doesn't know how to do SW coordination. HW coordiation is the simplest thing for the SW because SW doesn't have to know anything at all about topology constraints. It is also the simplest thing for the BIOS, which doesn't have to correctly describe topology. Yes, there is an MSR bit that the BIOS can flip to disable HW coordination. 90% of the time that bit is set it is a BIOS bug. eg. the bit is set, but the BIOS fails to properly set up the ACPI tables to properly enable SW coordination, resulting in a system with really strange performance issues. Indeed, I proposed before, and I will propose again that the underlying ACPI _PSD support behind SW coordination be completely removed from Linux. Venki, I recall that you mentioned one platform that depends on it -- and I'd like to understand that issue and address it with a quirk rather than expose all systems to BIOS bugs due to bogus _PSD support. Winston, Your system is running in SW coordination mode? What do you see if you run with the patch below? I'd be intersted to see the output from adpidump for your system. thanks, -Len Brown Intel Open Source Technology Center --- diff --git a/include/acpi/pdc_intel.h b/include/acpi/pdc_intel.h index 552637b..d081595 100644 --- a/include/acpi/pdc_intel.h +++ b/include/acpi/pdc_intel.h @@ -22,7 +22,6 @@ #define ACPI_PDC_EST_CAPABILITY_SWSMP (ACPI_PDC_SMP_C1PT | \ ACPI_PDC_C_C1_HALT | \ - ACPI_PDC_SMP_P_SWCOORD | \ ACPI_PDC_SMP_P_HWCOORD | \ ACPI_PDC_P_FFH)