RequesterAware Power Reduction

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Requester-Aware Power Reduction

• Yung-Hsiang Lu, Luca Benini
• Giobanni De Micheli
• ISSS00

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Introduction

• Motivation
• PM was implemented in two ways
• PM predicts future workload by observing requests
  at devices (APM)
• without direct interaction with requesters
• program can directly control power state (RCPM)
• Neither extreme is appropriate

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Introduction

• Paper proposes
• one approach between the two extremes
• programs can specify what devices are needed
  before generating requests
• Contributions
• explain the advantages to distinguishing
  individual requesters
• API which allows programs to indicate their
  device requirement
• build experimental environment

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Autonomous Power Management
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Autonomous Power Management

• Draw back
• requests comes from different programs
• have different power consumption patterns
• ex) ftp, telnet, netscape (considering NIC)
• without information about requesters
• may waste power to maintain performance
• ex) program can finish, no program requires a
  device

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Requester-Controlled Power Management
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ACPI ( RCPM example )

• An interface specification
• Defines
• Hardware registers - implemented in chipset
  silicon
• BIOS interfaces
• System and device power states

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ACPI System Overview
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Requester-Controlled power Management

• Draw back
• no well-defined rules to distinguish power states
• may set the same device to different power state
• hardware parameter is not static

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Approach in this paper

• Requesters(Processes) actively specify which
  devices will be used
• thus, get two benefit
• when no process uses a device, device can sleep
  immediately
• process schedulers arrange the order of execution

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Process Scheduling PM
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Performance Based API

• PB API
• interface between PM and programs

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Performance Based API
Some Examples
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Big Picture
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Experimental Setup
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Experimental Setup

• Use a one-hour three-phase workload
• 1. Sends a file of 50MB
• 2. Receives a file of 50MB
• 3. Periodically requests for acknowledgment.
• period 10 seconds, repeat 50 times
• between adjacent phases
• NC is idle for five minutes

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Results
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Results
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Results