1 enterprise platforms group pinpointing representative portions of large intel itanium programs...

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Pinpointing Representative Portions of Large Intel Itanium

Programs with Dynamic Instrumentation

Harish Patil, Robert Cohn, Mark Charney, Rajiv Kapoor, Andrew

Sun, Anand Karunanidhi

Enterprise Platform GroupIntel Corporation

Presented at MICRO-37: Portland, OR, Dec. 6th, 2004

IA32/EM64T/IPF

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Target: LARGE Applications

• With little/no manual intervention

• Within reasonable time

Goal: Accurate Performance Prediction

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Instruction Counts : Some Itanium Applications

# Instructions (billions)

142 373 463

3,979 3,994

4,932

SPECINT (average)

SPECFP (average)

RenderManmagic

Fluent L2

Amber rt

Ls-Dyna 3cars

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Whole-Program Simulation is Slow

Simulation Time in YEARS@ 10,000 Instructions/Second

0.4 1.2 1.5

12.6 12.715.6

SPECINT (average)

SPECFP (average)

RenderManmagic

Fluent L2

Amber rt

Ls-Dyna 3cars

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Solution: Select Simulation Points

• Manually• Randomly

– Anywhere– From uniform regions

• Fine-grain sampling (SMARTS: CMU)• By program-phase analysis

(SimPoint:UCSD, iPart: Intel/MRL)

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Running Commercial Applications on Simulators is Hard

• Resource Requirements: Disks etc.– Need to modify/re-configure the simulator

• OS dependencies– Need support for specific kernel and

device drivers

• License checking– Need special action

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Use PIN to select simulation points (PinPoints) and generate traces

PIN: A dynamic-instrumentation system+ A tool for writing tools+ No special compiler/linker flags required

Solution: Native Execution with Instrumentation

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PIN-Tools: Profiling, Trace Generation and more….

PIN-based profiler

Simulation Point

Selection

ProfilePinPoints

PIN-based Trace

Generator

PIN-based Branch

Predictor

Your Simulator Here

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Simulation Point Selection withSimPoint [UCSD]

Why SimPoint?

• Instrumentation based

• Microarchitecture independent

• Works well (results later)

Applied to multi-threaded programs

PIN-based profiler

SimPoint Tools

Basic BlockVectors PinPoints

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Multiple Sources of Error

Goal: Accurate Performance Prediction

Error Source: Phase detection

Error Source: Non-repeatability

Error Source: Warm-up, Modeling

PinPoints TracesSimulationStats (CPI)

Phase-detection is not enough!

Need Trace Generation and Simulation

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Main Contributions• A Toolkit that automatically:

– Profiles, finds phases/ simulation regions (PinPoints)

–Validates that PinPoints are representative

–Generates traces for simulators

Available for Itanium/IA32/EM64T

• Evaluations in a production environment

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The PinPoints Toolkit

PinPoints file

H/W counters-based Validation

(pfmon : ItaniumPAPI : IA32)

Compute CPI

Match?

Whole ProgramWeighted Sum

for PinPoints

Phase Detection+ PinPoint Selection

Trace Generation/Simulation

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EvaluationsApplications: Built w/ Intel’s compilers (high opt)

HPC: Fluent, AMBER, LS-Dyna, RenderMan SPEC2000: Processed 8-9 times

Test Configurations: Linux (RedHat)

Merced Itanium (1) 800 MHz L3: 2MB

McKinley Itanium-2 900 MHz L3: 1.5MB

Madison Itanium-2 1.3 GHz L3: 3-6 MB

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• PinPoints << 1% of program execution•Turnaround time (Traces) : Few days

PinPoints Generated

Program # Retired Instructions

(billions)

# PinPoints (250 million insts. EACH)

AMBER-rt 3,994 6

Fluent-m3 2,625 8

LS-DYNA 4,932 6

SPECINT2000(avg.) 142 4

SPECFP2000(avg.) 373 5

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Results: Overview• PinPoints: Whole-Program CPI prediction

(SPEC2000 and HPC applications):– Average CPI prediction error ~5%– PinPoints better than random selection

• Predicting speedup between microarchitectures

– PinPoints can be used to evaluate microarchitecture variations

• PinPoints Traces: Prediction of native SPEC2000 ratios

– INT within 8% FP within 3%More results in the paper

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0.1

0.6

1.1

1.6

2.1

CP

I

Whole_pgm_CPI

PinPoints_CPI

CPI: Actual vs. PredictedSPEC2000: Itanium-Madison

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SPEC2000 CPI PredictionAverage Error: Madison : 2.8%

Merced : 3.2% McKinley : 2.7%

0.1

0.6

1.1

1.6

2.1

CP

I

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

% A

bs

(De

lta

in

CP

I)

%Delta

Whole_pgm_CPI

PinPoints_CPI

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HPC Applications CPI PredictionAverage Error: Madison : 5.0%

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

CP

I

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

% A

bs(d

elta

CP

I)

%Delta

Whole_pgm_CPI PinPoints_CPI

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Cumulative Distribution of CPI Errors for SPEC2000

5%

15%

25%

35%

45%

55%

65%

75%

85%

95%

0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20% 22% 24% 26% 28% 30%

CPI Error

% o

f R

un

s

PinPoints : N Points

Random: N Points

Uniform Random : N Points

Comparison With Random Selection[ 48 unique program runs ]

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Cumulative Distribution of CPI Errors for HPC apps.

5%

15%

25%

35%

45%

55%

65%

75%

85%

95%

0% 2% 4% 6% 8% 10% 12% 14% 16% 18% 20% 22% 24% 26% 28% 30%

CPI Error

% o

f R

un

s

PinPoints : N Points

Random: N Points

Uniform Random : N Points

Comparison With Random Selection[ 18 unique program runs ]

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Speedup: Merced McKinleySPEC2000

0123456

Spe

edup

McKinley:Actual

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PinPoints Speedup Prediction: SPEC2000: Merced McKinley

0

1

2

3

4

5

6

Spe

edup

McKinley:Actual

McKinley:Predicted

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PinPoints: Speedup Prediction Across Multiple Microarchitectures

Same Binaries/PinPoints

0

1

2

3

4

5

6

Sp

eed

up

McKinley:ActualMcKinley:PredictedMadison:ActualMadison:Predicted

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Putting it All Together:From PinPoints to Projections

PinPoints TracesSimulationStats (CPI)

Does simulation of traces for PinPoints predict native performance?

Error Source: Phase detection

Error Source: Non-repeatability

Error Source: Warm-up, Modeling

Error: Cumulative

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CPI Prediction with SimulationSPEC2000: Itanium Madison

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

CPI

0%10%20%30%40%50%60%70%80%90%100%

Abs

(% D

elta

)

% Delta

Actual: Native Hardware

Simulated: PinPoints(traces)

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Native SPEC2000 Ratios[Spring 2004]

Itanium: Madison 1.5GHz/6MB L3

2075

1174

0

500

1000

1500

2000

2500

SPECfp SPECint

SP

EC

Rat

io

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Performance Prediction from PinPoints Traces

Itanium: Madison 1.5GHz/6MB L3

2075

1174

2126

1270

0

500

1000

1500

2000

2500

SPECfp SPECint

SP

EC

Rat

io

Native Simulated

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Summary

PinPoints toolkit : Automatic simulation region selection, tracing, and validation

Dynamic instrumentation (PIN ) LARGE programs

• PinPoints: << 1% of executionCapture whole-program CPI– Average error < 5% for SPEC2000, HPC apps.– Better than random selection

• PinPoints traces: Predict SPEC2000 Ratios– INT within 8% FP within 3%

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Try it out!

(PIN + PinPoints) toolkit :

http://rogue.colorado.edu/Pin

New

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Backup: Simulator Warm-up• Strategy 1: Large slice-size (250 million

instructions)– Too coarse-grain for phase detection– Too much simulation time

• Strategy 2: 7 warm-up traces per simulation trace (30 million instructions)

Art (SPECFP2000): First pinpoint touches most of the working set– Simulate all pinpoint traces in

succession

1 enterprise platforms group pinpointing representative portions of large intel itanium programs...

Documents

instrumentation slide

mb slide

intelmrl slide

ia32em64tipf slide

simulation points pinpoints

special action slide

program simulation

production environment