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PowerSpy: Fine Grained Power Profiler. Kutty S Banerjee Emmanuel Agu. Mobile Devices – Energy Crisis. Rate of Growth of CPU Memory Disk Space Wireless Transfer Speed Far Greater than that of Battery Energy !!.

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powerspy fine grained power profiler

PowerSpy:Fine Grained Power Profiler

Kutty S Banerjee

Emmanuel Agu

mobile devices energy crisis
Mobile Devices – Energy Crisis
  • Rate of Growth of
    • CPU
    • Memory
    • Disk Space
    • Wireless Transfer Speed

Far Greater than that of Battery Energy !!

Powerful Change Part1:Batteries and Possible Alternatives for the Mobile Market. IEEE Pervasive Computing,October-December 2003 (Vol. 2, No. 4)

powerspy
PowerSpy

Helps answer the following questions:

  • Which Thread consumes How much power?
  • What procedures in each thread are invoked?
  • Which I/O Device consumes how much power?
    • <Application initiated I/O>
powerspy features
PowerSpy Features:
  • Non Intrusive of Kernel Source
  • Non Intrusive of Application Source
  • `Software-Only’
  • Accurate Billing sans OS activities
  • Windows 2000,XP,Server 2003
powerspy usage
PowerSpy Usage
  • Installation:
    • Powerspy.sys (kernel mode driver)
      • Installation Requires Administrative Privilege
    • Powerspy.exe (user mode application)
    • Windows XP (run checked build)
      • Boot option `/debug’ flag set
  • Usage:
    • powerspy devenv.exe (Microsoft Visual Studio)
    • Produces `report.dat’ . Results next…
thread and i o profiling
Thread and I/O Profiling

Thread Power Usage

Device Power Usage

application profiled
Application Profiled
  • OpenVRML
    • VRML Browser (disk heavy)
    • Graphics appln.
  • Mozilla
    • I/O heavy (Network heavy)
  • Windows Media Player
    • I/O heavy (Network heavy)
power measurement approaches
Power Measurement Approaches
  • Measure Power Loss - Application Runtime
    • Hardware (PowerScope)
    • Software (PowerSpy)
  • Break Application Runtime ->Finite Elements
    • Power Consumption Finitie Elements Known prior
    • Sum to get total power
powerscope approach
PowerScope Approach
  • Hardware multimeter measures current, voltage.
  • Samples PC, PID, ISR
  • Analysis offline
os context switches
OS Context Switches
  • Time of execution of thread=quantum
  • Need to monitor `current thread of execution’ as often as quantum period
  • What about preemption? We’ll see next…

System Architecture

pseudo code algorithm
Pseudo Code Algorithm

if(measurePowerOn_==true)

{

if(currentThread_!=SchedulerThread())

measurePowerOn_=false;

tempPower_=instPower_;

instPower_=measurePower();

totalPower_=tempPower_-instPower_;

}

else

{

if(currentThread_==SchedulerThread())

{

measurePowerOn_=true;

instPower_=measurePower();

}

}

i o device monitor1
I/O Device Monitor
  • Question ->Do you check all I/O Devices live in system ?
    • Push on stack question until Implementation!!
  • Question -> What if thread does overlapped I/O with `n’ devices?
    • Limitation of PowerSpy. We cannot distinguish b/w them!!
what about procedures
What about Procedures?
  • Two Approaches?
    • Invasive – Add stub of code in executable in each procedure for all modules
      • Stub merely records itself!!
    • NonInvasive – Simply check PC at sampled intervals. (POWERSPY APPROACH)
      • Use Module Export/Import Table
      • Base Loading Address

For address to module,procedure translation!!

windows scheduling policy
Windows Scheduling Policy
  • Preemptive Priority driven.
  • Get current thread running (last running) PsGetCurrentThreadId (kernel mode call)
  • To monitor Scheduler
    • Need to be at same priority
    • Must be non preemptable by Scheduler
    • DPC (Deferred Procedure Calls) execute at same priority as Windows Scheduler called `Dispatcher’
    • Timed DPC running at 10ms=roughly equal to Windows standard quantum.
    • Every 10ms, DPC preempts Scheduler and executes algorithm.
    • 10ms NOT GUARANTEED EXACT!!Windows is NOT REAL TIME!!
monitor i o operations
Monitor I/O Operations
  • All user mode appln do I/O by Win32 API
  • Win32 API forwards request to I/O Manager
  • I/O Manager creates IRP (I/O Request Packet) and forwards to appropriate Device Driver.
  • For every thread( user mode or kernel mode), internal OS data structure (undocumented) -> ETHREAD.
  • ETHREAD contains list of IRPs thread currently blocked on.
  • IRP contains name of I/O Devices.
  • Therefore, thread to I/O Device located!!
  • ETHREAD maintained in `ntoskrnl.exe’. Not Exported!! Therefore need `debug symbols’. Hence need to run `checked build of Windows’.
  • Have access to Internet!! Symbol Server of Microsoft at http://msdl.microsoft.com
limitations
Limitations
  • Thread Blocked on I/O Device DOES NOT mean I/O Device currently executing its order!!
  • I/O Device has internal queue.
  • Thread 4 blocked and billed but not actually serviced!! Excess Power billed!!
  • Procedures NOT CALL GRAPH!!
reference
Reference
  • Inside Windows 2000
  • Programming Applications for MS Windows
  • Windows Loader – Matt Pietrik
  • www.sysinternals.com
  • www.osronline.com
  • Powerscope
  • Windows DDK
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