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METHOD OF SERVER THROTTLING IN BLADE AND MICRO SERVER CHASSIS

IP.com Disclosure Number: IPCOM000246278D
Publication Date: 2016-May-23

Publishing Venue

The IP.com Prior Art Database

Related People

Nan Wang: AUTHOR [+4]

Abstract

Presented herein is a method to throttle the performance of a server based on the server's workload and the power supply unit (PSU) condition, which can achieve a better balance between power and performance. When some servers are working at peak power, a central throttle unit (CTU) will throttle some of the other servers in the chassis to ensure the servers run at peak power as long as possible. When the PSU hits over power protection (OPP) limit, the CTU will throttle some of the server nodes rather than all servers in the chassis. The CTU will pick those servers with lower power to throttle. Thus, a server with a high workload can avoid the influence of the entire chassis being throttled by CTU control.

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METHOD OF SERVER THROTTLING IN BLADE AND MICRO SERVER CHASSIS

AUTHORS:

Nan Wang

 Yang Sun Bruce Chen

Zomin Gan

CISCO SYSTEMS, INC.

ABSTRACT

    Presented herein is a method to throttle the performance of a server based on the server's workload and the power supply unit (PSU) condition, which can achieve a better balance between power and performance. When some servers are working at peak power, a central throttle unit (CTU) will throttle some of the other servers in the chassis to ensure the servers run at peak power as long as possible. When the PSU hits over power protection (OPP) limit, the CTU will throttle some of the server nodes rather than all servers in the chassis. The CTU will pick those servers with lower power to throttle. Thus, a server with a high workload can avoid the influence of the entire chassis being throttled by CTU control.

DETAILED DESCRIPTION

    A central processing unit (CPU) used in computer servers running in best performance is required to run at higher frequency with more. When deployed in a datacenter, power supply and cooling costs keep increasing and there is a greater focus on the balance between the power usage and performance. Improving datacenter energy efficiency is becoming a fundamental requirement.

    The CPU could run at a higher frequency with better performance for datacenter server applications. Take an Intel CPU as an example, the thermal designed power (TDP) is limited by the thermal, but the peak power of the CPU could as much as double of the TDP to get the best performance. Normally, the hardware and power supply design are

Copyright 2016 Cisco Systems, Inc.

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based on the TDP, and a throttle circuit is needed to avoid unexpected issues when the system is running at peak power.

    Intel and power supply unit (PSU) vendors have developed a PSU specification to define the power supply requirements for Intel-based server and workstation systems. The power supplies' over power protection (OPP) limits the current output of the power supply to protect against overstress of components. The power supply becomes a current source and voltage folds back to limit power. The power supply asserts an SMBALERT signal before the output current hits the OPP point; this will quickly throttle the system power. An added buffer capacitance is used to support the voltage during the delay between hitting OPP and power throttling. The figure shows a simple equation that can be used to calculate the needed capacitance given the throttling delay.

Figure 1: Pmax Protection

    The power supply may have a circuit to quickly assert the SMBALERT signal when the output current exceeds the 130% current. The SMBALERT signal is asserted within 10usec. The power supply holds the SMBALERT signal asserted for 100msec duration then release it. The SMBALERT is connected to all servers as PROCHOT signal in the chassis.

    Once the server is throttled, the CPU would be held in Pn, which could be the lowest spin of CPU frequenc...