Technical white paper HP ProLiant Server Power Management Red Hat Enterprise Linux 6.x Table of contents Abstract 2 Introduction 2 HP Power Regulator 2 HP Power Capping 4 Power monitoring with HP iLO 4 5 Power capping demonstration with HP iLO 4 5 ProLiant power management with RHEL 6.x 7 Collaborative power control with RHEL 6.x 8 Idle power states (C-States) with RHEL 6.x 9 Additional RHEL 6.x power management features 9 Firmware bug issue under RHEL 6.
Abstract Power management is crucial to data center power provisioning. This document provides a brief overview of the processor-based power saving features supported on HP ProLiant servers and the power management features such as Power Regulator, Power Capping and Collaborative Power Control that are embedded in the ProLiant platforms. This document also discusses how these features are used and their relationship to the Red Hat Enterprise Linux (RHEL) 6.x (6.0, 6.1, 6.2 and 6.
HP Static High The firmware controls the P-states. The P-state of the processor is static and it is set to P0 which corresponds to the highest operating frequency supported by the processor. OS Control The RHEL 6.x operating system controls the P-states and it manages the P-states according to the policy set by the administrator via the OS. For the HP Static Low and HP Static High modes above, you are advised to disable CPC to ensure that the firmware has exclusive control of the P-states.
Figure 2: Configuring the Collaborative Power Control (CPC) setting via RBSU For more information on HP Power Regulator technology, see: http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00300430/c00300430.pdf HP Power Capping HP Power Capping satisfies data center power provisioning requirements by allowing the data center administrator to provide a power budget to a single-server or a group of servers.
Power monitoring with HP iLO 4 HP iLO 4 supports the facility to monitor current power consumption along historical timelines. As shown in Figure 3, HP iLO 4 displays the current power consumption as well as the peak and average power consumptions for the past 24-hour and 20-minute time periods. Figure 3: HP iLO 4 power meter readings for 24-hour and 20-minute time periods For more information on the HP Integrated Lights-Out (iLO) management technology, see: www.hp.
Figure 4: HP Power Capping threshold configuration Figure 5: Power consumption without capping 6
Figure 6: Power consumption with capping ProLiant power management with RHEL 6.x RHEL 6.x manages the power usage of ProLiant servers by adjusting the processor P-states when the HP Power Regulator setting in RBSU is configured in OS Control mode. Typically within the Linux operating system, a governor dictates the policy, while the actual P-state transition is accomplished by a suitable P-state driver. RHEL 6.
Example 1: Output for CPU 0 in OS Control mode # cpufreq-info -c 0 cpufrequtils 007: cpufreq-info (C) Dominik Brodowski 2004-2009 Report errors and bugs to cpufreq@vger.kernel.org, please. analyzing CPU 0: driver: acpi-cpufreq CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: 10.0 us. hardware limits: 1.20 GHz - 2.00 GHz available frequency steps: 2.00 GHz, 2.00 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.
available cpufreq governors: ondemand, userspace, performance current policy: frequency should be within 1.20 GHz and 2.00 GHz. The governor "ondemand" may decide which speed to use within this range. current CPU frequency is 1.20 GHz. Idle power states (C-States) with RHEL 6.x Processor power use at idle is a crucial factor in determining power consumption of a server when there is no workload to execute.
Note The May 2012 release of PowerTOP v2.0 can be compiled on RHEL 6.3; it cannot be compiled successfully on RHEL 6.0, 6.1, and 6.2 because the libnl library on each of these versions is out of date. An additional RPM package pciutilsdevel7 must be installed on RHEL 6.3. The RPM package is not included in RHEL 6.3 media. Figure 7: PowerTOP v1.11 output on an idle ProLiant DL360e Gen8 running under RHEL 6.
Figure 8: PowerTOP v2.0 output on an idle ProLiant DL360e Gen8 running under RHEL 6.3 with no IPMI service Firmware bug issue under RHEL 6.x When booting into RHEL 6.x, a firmware bug message will be logged as shown in Figure 9. The Linux kernel reports that BIOS occupies the MSR (Model-specific register) address 0x38d. The address represents the fixed-function performance counter control register (IA32_FIXED_CTR_CTRL) defined in the Intel specification8.
Figure 9: Firmware bug symptom on a ProLiant DL360e Gen8 server This firmware bug message does not impact the perf performance counter subsystem because the subsystem is executed continuously (as you can see by the message “Intel PMU driver.” in Figure 9), which means the subsystem still works properly. To support the performance monitoring functionality, the subsystem uses the generalpurpose performance counters instead of the fixed-function performance counters. This approach avoids the MSR conflict.
Figure 10: Disabling the Processor Power and Utilization Monitoring option in RBSU Summary HP ProLiant servers are capable of saving power both when the server is under load and when the server is idle. The processor-based power management features supported in the hardware are enabled by the firmware automatically, and are used in close coordination between the firmware and the RHEL 6.x operating system. Typically, you do not have to activate these features; they are already enabled by default.
For more information For additional information, refer to the resources listed below. Resource description Web address HP ProLiant Gen8 Power Regulator http://www.hp.com/go/proliantgen8 http://www.hp.com/go/linux-docs, select HP Linux Server Management Software http://www.hp.com/servers/power-regulator HP Power Capping and HP Dynamic Power Capping http://h20000.www2.hp.com/bc/docs/support/SupportManual/c015494 55/c01549455.pdf Power Regulator for ProLiant servers http://h20000.www2.hp.
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