From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752201AbaLFCQr (ORCPT ); Fri, 5 Dec 2014 21:16:47 -0500 Received: from mail-pa0-f52.google.com ([209.85.220.52]:56221 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751398AbaLFCQp convert rfc822-to-8bit (ORCPT ); Fri, 5 Dec 2014 21:16:45 -0500 References: <1417772453-22483-1-git-send-email-ethan.zhao@oracle.com> <5481D8B9.2030603@hp.com> Mime-Version: 1.0 (1.0) In-Reply-To: <5481D8B9.2030603@hp.com> Content-Type: text/plain; charset=gb2312 Content-Transfer-Encoding: 8BIT Message-Id: Cc: Ethan Zhao , "dirk.j.brandewie@intel.com" , "kristen@linux.intel.com" , "viresh.kumar@linaro.org" , "rjw@rjwysocki.net" , "corbet@lwn.net" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-pm@vger.kernel.org" , "alexey.kodanev@oracle.com" X-Mailer: iPad Mail (12B435) From: ethan Subject: Re: [PATCH 2/2 V8] intel_pstate: add kernel parameter to force loading. Date: Sat, 6 Dec 2014 10:16:37 +0800 To: Linda Knippers Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linda， > 在 2014年12月6日，00:09，Linda Knippers 写道： > >> On 12/5/2014 4:40 AM, Ethan Zhao wrote: >> To force loading on Oracle Sun X86 servers, provide one kernel command line >> parameter >> >> intel_pstate = force >> >> For those who be aware of the risk of no power capping capabily working and >> try to get better performance with this driver. >> >> Signed-off-by: Ethan Zhao >> Tested-by: Alexey Kodanev >> --- >> v2: change to hardware vendor specific naming parameter. >> v4: refine code and doc. >> v5&v6: fix a typo in doc. >> v7: change enum PCC to PPC. >> v8: change the name of kernel command line parameter to generic one. >> >> Documentation/kernel-parameters.txt | 5 +++++ >> drivers/cpufreq/intel_pstate.c | 6 +++++- >> 2 files changed, 10 insertions(+), 1 deletion(-) >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 479f332..7d0983e 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. >> disable >> Do not enable intel_pstate as the default >> scaling driver for the supported processors >> + force >> + Enable intel_pstate on systems where it may cause problems to >> + happen due to conflicts with platform firmware attempting to >> + drive P-states by itself in certain situations (for thermal >> + control or power capping in general or other purposes). > > I suggest something like: > Enable intel_pstate on systems that prohibit it by > default in favor of acpi-cpufreq. Forcing the > intel_pstate driver instead of acpi-cpufreq may disable > platform features, such as thermal controls and power > capping, that rely on ACPI p-state information being P-States > Used by the OS and therefore should be used with care. Indicated to OSPM caution > This option does not work with processors that aren't > supported by the intel_pstate driver or on platforms > that use pcc-cpufreq instead of acpi-cpufreq. > > Maybe this is too specific but I believe it is accurate. Comments? > Looks better to me, except some words commented. Thanks, Ethan > -- ljk > >> >> intremap= [X86-64, Intel-IOMMU] >> on enable Interrupt Remapping (default) >> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c >> index 1bb62ca..2654e13 100644 >> --- a/drivers/cpufreq/intel_pstate.c >> +++ b/drivers/cpufreq/intel_pstate.c >> @@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = { >> }; >> >> static int __initdata no_load; >> +static unsigned int force_load; >> >> static int intel_pstate_msrs_not_valid(void) >> { >> @@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void) >> case PSS: >> return intel_pstate_no_acpi_pss(); >> case PPC: >> - return intel_pstate_has_acpi_ppc(); >> + return intel_pstate_has_acpi_ppc() && >> + (!force_load); >> } >> } >> >> @@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str) >> >> if (!strcmp(str, "disable")) >> no_load = 1; >> + if (!strcmp(str, "force")) >> + force_load = 1; >> return 0; >> } >> early_param("intel_pstate", intel_pstate_setup); >