METRICS: A System Architecture for Design Process Optimization

1
METRICSA System Architecture for Design Process
Optimization

• Andrew B. Kahng and Stefanus Mantik
• UCSD CSE and ECE Depts., La Jolla, CA
• UCLA CS Dept., Los Angeles, CA

2
Motivations

• How do we improve design productivity ?
• Does our design technology / capability yield
  better productivity than it did last year ?
• How do we formally capture best known methods,
  and how do we identify them in the first place ?
• Does our design environment support continuous
  improvement of the design process ?
• Does our design environment support what-if /
  exploratory design ? Does it have early
  predictors of success / failure?
• Currently, there are no standards or
  infrastructure for measuring and recording the
  semiconductor design process

3
Purpose of METRICS

• Standard infrastructure for the collection and
  the storage of design process information
• Standard list of design metrics and process
  metrics
• Analyses and reports that are useful for design
  process optimization

METRICS allows Collect, Data-Mine, Measure,
Diagnose, then Improve
4
Related Works

• OxSigen LLC (Siemens 97-99)
• Enterprise- and project-level metrics
  (normalized transistors) Numetrics Management
  Systems DPMS
• Other in-house data collection systems
• e.g., TI (DAC 96 BOF)
• Web-based design support
• IPSymphony, WELD, VELA, etc.
• E-commerce infrastructure
• Toolwire, iAxess, etc.
• Continuous process improvement
• Data mining and visualization

5
Outline

• Data collection process and potential benefits
• METRICS system architecture
• METRICS standards
• METRICS for design flow
• METRICS integration with datamining
• Current implementation
• Issues and conclusions

6
Potential Data Collection/Diagnoses

• What happened within the tool as it ran? what was
  CPU/memory/solution quality? what were the key
  attributes of the instance? what
  iterations/branches were made, under what
  conditions?
• What else was occurring in the project? spec
  revisions, constraint and netlist changes,
• Example diagnosis User performs same operation
  repeatedly with nearly identical inputs
• tool is not acting as expected
• solution quality is poor, and knobs are being
  twiddled

7
Benefits

• Benefits for project management
• accurate resource prediction at any point in
  design cycle
• up front estimates for people, time, technology,
  EDA licenses, IP re-use...
• accurate project post-mortems
• everything tracked - tools, flows, users, notes
• no loose, random data left at project end
• management console
• web-based, status-at-a-glance of tools, designs
  and systems at any point in project
• Benefits for tool RD
• feedback on the tool usage and parameters used
• improve benchmarking

8
Outline

• Data collection process and potential benefits
• METRICS system architecture
• METRICS standards
• METRICS for design flow
• METRICS integration with datamining
• Current implementation
• Issues and conclusions

9
METRICS System Architecture
10
METRICS Performance

• Transmitter
• low CPU overhead
• multi-threads / processes non-blocking scheme
• buffering reduce number of transmissions
• small memory footprint
• limited buffer size
• Reporting
• web-based
• platform and location independent
• dynamic report generation
• always up-to-date

11
XML Example
ltMETRICS_LISTgt ltMETRIC PID134 FID22
TID47gt ltNAMEgtTOTAL_WIRELENGTHlt/NAMEgt ltVALUE
gt14250347lt/VALUEgt ltTYPEgtINTEGERlt/TYPEgt ltTIMEST
AMPgt010312220512lt/TIMESTAMPgt lt/METRICgt ltMETRIC
PID134 FID22 TID47gt ltNAMEgtTOTAL_CPU_TIM
Elt/NAMEgt ltVALUEgt2150.28lt/VALUEgt ltTYPEgtDOUBLElt/
TYPEgt ltTIMESTAMPgt010312220514lt/TIMESTAMPgt lt/ME
TRICgt lt/METRICS_LISTgt
12
Transmitter Examples

• Wrapper-based transmitter
• !/usr/local/bin/perl -w
• TOOL 0
• PID initProject
• FID initFlow -pid PID
• TID initToolRun -pid PID -fid FID
• system sendMetrics TOOL_NAME TOOL\ STRING
• while(ltINgt)
• system sendMetrics NAME VALUE\ TYPE
• system terminateToolRun
• system terminateFlow -pid PID -fid FID
• system terminateProject -pid PID
• exit 0

• API-based transmitter
• include transmitter.h
• int main(int argc, char argv)
• Transmitter MTR
• MTR.initProject()
• MTR.initFlow()
• MTR.initToolRun()
• MTR.sendMetrics(TOOL_NAME, argv0,\
  STRING)
• MTR.sendMetrics(Name, Value, Type)
• MTR.terminateToolRun()
• MTR.terminateFlow()
• MTR.terminateProject()
• exit 0

13
Example Reports
CPU_TIME 12 0.027 NUM_CELLS Correlation 0.93
14
METRICS Server
Apache
Reports
Reporting Servlets
SQL via JDBC
Oracle 8i
Requests
SQL via JDBC
Transmitter Servlets
15
Open Source Architecture

• METRICS components are industry standards
• e.g., Oracle 8i, Java servlets, XML, Apache web
  server, PERL/TCL scripts, etc.
• Custom generated codes for wrappers and APIs are
  publicly available
• collaboration in development of wrappers and APIs
• porting to different operating systems
• Codes are available at http//vlsicad.cs.ucla.edu
  /GSRC/METRICS

16
Outline

• Data collection process and potential benefits
• METRICS system architecture
• METRICS standards
• METRICS for design flow
• METRICS integration with datamining
• Current implementation
• Issues and conclusions

17
METRICS Standards

• Standard metrics naming across tools
• same name same meaning, independent of tool
  supplier
• generic metrics and tool-specific metrics
• no more ad hoc, incomparable log files
• Standard schema for metrics database
• Standard middleware for database interface
• For complete current lists see
  http//vlsicad.cs.ucla.edu/GSRC/METRICS

18
Generic and Specific Tool Metrics
Partial list of metrics now being collected in
Oracle8i
19
Outline

• Data collection process and potential benefits
• METRICS system architecture
• METRICS standards
• METRICS for design flow
• METRICS integration with datamining
• Current implementation
• Issues and conclusions

20
Flow Metrics

• Tool metrics alone are not enough
• Design process consists of more than one tool
• A given tool can be run multiple times
• Design quality depends on the design flow and
  methodology (the order of the tools and the
  iteration within the flow)
• Flow definition
• Directed graph G (V,E)
• V ? T ? S, F
• T ? T1, T2, T3, , Tn (a set of tasks)
• S ? starting node, F ? ending node
• E ? Es1, E11, E12, , Exy (a set of edges)
• Exy
• x lt y ? forward path
• x y ? self-loop
• x gt y ? backward path

21
Flow Example
S
T1
T2
T3
Optional task
T4
F
Task sequence T1, T2, T1, T2, T3, T3, T3, T4,
T2, T1, T2, T4
22
Flow Tracking
Task sequence T1, T2, T1, T2, T3, T3, T3, T4,
T2, T1, T2, T4
23
Optimization of Incremental Multilevel FM
Partitioning

• Motivation Incremental Netlist Partitioning
• netlist ECOs are made want top-down placement
  to remain similar to previous result
• good approach CaldwellKM00 V-cycling based
  multilevel Fiduccia-Mattheyses
• what is the best tuning of the approach for a
  given instance?
• break up the ECO perturbation into multiple
  smaller perturbations?
• starts of the partitioner?
• within a specified CPU budget?

24
Optimization of Incremental Multilevel FM
Partitioning

• Given initial partitioning solution, CPU budget
  and instance perturbations (?I)
• Find number of parts of incremental partitioning
  and number of starts
• Ti incremental multilevel FM partitioning
• Self-loop ? multistart
• n ? number of breakups (?I ?1 ?2 ?3 ...
  ?n)

25
Multilevel FM Experiment Flow Setup

• foreach testcase
• foreach ?I
• foreach CPUbudget
• foreach breakup
• Icurrent Iinitial
• Scurrent Sinitial
• for i 1 to n
• Inext Icurrent ?i
• run incremental multilevel FM partitioner
• on Inext to produce Snext
• if CPUcurrent gt CPUbudget then break
• Icurrent Inext
• Scurrent Snext
• end

26
Flow Optimization Results

• If (27401 lt num edges ? 34826) and (143.09 lt cpu
  time ? 165.28) and (perturbation delta ? 0.1)
  then num_inc_parts 4 and num_starts 3
• If (27401 lt num edges ? 34826) and (85.27 lt cpu
  time ? 143.09) and (perturbation delta ? 0.1)
  then num_inc_parts 2 and num_starts 1
• ...

27
Identifying the Effect of Wire Load Model

• Wire load model (WLM) is used for pre-layout
  estimation of wire delays
• Three different WLMs
• statistical WLM
• structural WLM
• custom WLM
• Motivation
• identify if WLMs are useful for estimation
• identify if WLMs are necessary for optimization
• identify the best role of WLMs

28
Wireload Model Flow

• WLM flows for finding the appropriate role of WLM
• T1 synthesis technology mapping
• T2 load wireload model (WLM)
• T3 pre-placement optimization
• T4 placement
• T5 post-placement optimization
• T6 global routing
• T7 final routing
• T8 custom WLM generation

29
WLM Experiment Setup

• foreach testcase
• foreach WLM (statistical, structural, custom,
  and no WLM)
• foreach flow variant
• run PKS flow
• if WLM structural then
• generate custom WLM
• end

6 different flow variants
30
WLM Flow Results
Slack comparison for 6 flow variants

• Post-placement and pre-placement optimizations
  are important steps
• Choice of WLM depends on the design

31
Outline

• Data collection process and potential benefits
• METRICS system architecture
• METRICS standards
• METRICS for design flow
• METRICS integration with datamining
• Current implementation
• Issues and conclusions

32
Datamining Integration
Inter-/Intranet
DM Requests
SQL
Results
Tables
Database
Datamining Interface
Datamining Tool(s)
Tables
Tables
SQL
Results
33
Categories of Data for DataMining

• Design instances and design parameters
• attributes and metrics of the design instances
• e.g., number of gates, target clock frequency,
  number of metal layers, etc.
• CAD tools and invocation options
• list of tools and user options that are available
• e.g., tool version, optimism level, timing driven
  option, etc.
• Design solutions and result qualities
• qualities of the solutions obtained from given
  tools and design instances
• e.g., number of timing violations, total tool
  runtime, layout area, etc.

34
Possible Usage of DataMining

• Design instances and design parameters
• CAD tools and invocation options
• Design solutions and result qualities
• Given ? and ?, estimate the expected quality of ?
• e.g., runtime predictions, wirelength
  estimations, etc.
• Given ? and ?, find the appropriate setting of ?
• e.g., best value for a specific option, etc.
• Given ? and ?, identify the subspace of ? that is
  doable for the tool
• e.g., category of designs that are suitable for
  the given tools, etc.

35
Example Applications with DM

• Parameter sensitivity analysis
• input parameters that have the most impact on
  results
• Field of use analysis
• limits at which the tool will break
• tool sweet spots at which the tool will give best
  results
• Process monitoring
• identify possible failure in the process (e.g.,
  timing constraints are too tight, row utilization
  is too high, etc.)
• Resource monitoring
• analysis of resource demands (e.g., disk space,
  memory, etc.)

36
DM Results QPlace CPU Time

• If (num nets ? 7332) then CPU time 21.9
  0.0019 num cells 0.0005 num nets 0.07 num
  pads - 0.0002 num fixed cells
• If (num overlap layers 0) and (num cells ?
  71413) and (TD routing option false) then CPU
  time -15.6 0.0888 num nets - 0.0559 num cells
  - 0.0015 num fixed cells - num routing layer
• ...

37
Outline

• Data collection process and potential benefits
• METRICS system architecture
• METRICS standards
• METRICS for design flow
• METRICS integration with datamining
• Current implementation
• Issues and conclusions

38
Testbed I Metricized PR Flow
M E T R I C S
DEF
Placed DEF
LEF
Legal DEF
Congestion Map
Routed DEF
Final DEF
39
Testbed II Metricized Cadence SLC Flow
M E T R I C S
DEF
Placed DEF
Incr.
LEF GCF,TLF
Clocked DEF
Constraints
Optimized DEF
Routed DEF
40
Testbed III Metricized Cadence PKS Flow
M E T R I C S
BuildGates
41
NELSIS Flow Manager Integration

• Flow managed by NELSIS

42
Outline

• Data collection process and potential benefits
• METRICS system architecture
• METRICS standards
• METRICS for design flow
• METRICS integration with datamining
• Current implementation
• Issues and conclusions

43
Current Status

• Complete prototype of METRICS system is working
  at UCLA with Oracle8i, Java Servlet and XML
  (other working prototypes are installed at Intel
  and Cadence)
• METRICS wrapper for Cadence and Cadence-UCLA
  flows, front-end tools (Ambit BuildGates and
  NCSim)
• Easiest proof of value via use of regression
  suites
• METRICS system is integrated with Cubist
  datamining tool and NELSIS flow manager
• A complete METRICS system can be installed on a
  laptop and configured to work behind firewalls

44
Issues and Ongoing Work

• Issues for METRICS constituencies to solve
• security proprietary and confidential
  information
• standardization flow, terminology, data
  management, etc.
• social big brother, collection of social
  metrics, etc.
• Ongoing work with EDA, designer communities to
  identify tool metrics of interest
• users metrics needed for design process
  insight, optimization
• vendors implementation of the metrics
  requested, with standardized naming / semantics

45
Thank You
http//vlsicad.cs.ucla.edu/GSRC/METRICS