May 9, 20161

Harnessing Big Data to Simplify Debugging

May 9, 2016

Asi Lifshitz, CTO

www.thevtool.com

May 9, 20162

Agenda

• Introduction

• What is Big Data, Anyway?

• Simulation Log Files

• Graphical Representation of a Log File

• Summary

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RTL Debugging

• Verification is one of the major bottlenecks towards tape-out

• Debugging failing tests is complex and time-consuming

Source: Wilson Research & Mentor Graphics, 2014

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• Iterating between the waveforms and the simulation log file

• Simulation log files can reach several GB

Debugging Today

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• Big Data tools will quickly and efficiently extract data from huge log files

• Extracting and manipulating data gets simpler

• Data can be presented in a graphical way

• Shortening the debug time will shorten the project schedule and increase the engineer’s productivity

Debugging Tomorrow

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Agenda

• Introduction

• What is Big Data, Anyway?

• Simulation Log Files

• Graphical Representation of a Log File

• Summary

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• Big data is a term for data sets that are so large or complex that traditional data processing applications are inadequate

• The term often refers simply to the usage of advanced methods for extracting value from data, and seldom to a particular size of data set

Big Data

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• For some organizations, facing few gigabytes of data for the first time may trigger a need to reconsider data management options

• For others, it may take tens or hundreds of terabytes before data size becomes a significant consideration

Big Data – Cont.

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• A database is an organized collection of data

• The data is typically organized in a way that supports processes that require information

• A database management system (DBMS) is a computer software application that interacts with the user, other applications, and the database itself to capture and analyze data

Database

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• Database can be used to query a specific record, i.e., a specific message

• However, if some computation is required a database search engine is to be used

– A concrete example which goes beyond the capabilities of a database, is when the DV engineer would like to see all messages from time point tp1 to time point tp2

Database for Log Files

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• A search engine allows the user to search for information using simple keywords

Database Search Engine

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• A free and open-source database search engine, originally written in Java

• Has been ported to Delphi, Perl, C#, C++, Python, Ruby, and PHP

• Suitable for any application that requires full text indexing and searching capability

• The core of its logical architecture is the idea of a document containing fields of text

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Agenda

• Introduction

• What is Big Data, Anyway?

• Simulation Log Files

• Graphical Representation of a Log File

• Summary

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• A simulation log file is a structured textual file, and as such it can be indexed

• Once indexed, Lucene API can be used to search for all the ”interesting” events that are needed for debugging a failing test

Lucene for Verification

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• The Universal Verification Methodology (UVM) is a standardized methodology for verifying integrated circuit designs

• More than 70% of the industry have adopted UVM, and the numbers will only grow with time

UVM

Source: Wilson Research & Mentor Graphics, 2014

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• UVM-based simulation contains UVM messages that usually have the following format:

Verbosity

Filename(line)

Timepoint

Emitter

Message

UVM Messages

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• UVM_ERROR /project/sflash/verification/SFLASH_controller_ENV/src/sflash_controller_env_sb.sv(1863) @ 4498000: uvm_test_top.env.sb [WRITE_MODE_SPI_DATA_ERR] Sent data packet contains 0x532e4000, but expected 0x532e4cb3

• UVM ERROR is the verbosity (or severity)

• /project/sflash/verification/SFLASH_controller_ENV/src/sflash

_controller_env_sb.sv(1863) is the filename(line)

• @ 4498000 is the time point

• uvm_test_top.env.sb is the emitter of the message

• [WRITE_MODE_SPI_DATA_ERR] Sent data packet contains

0x532e4000, but expected 0x532e4cb3 is the message

UVM Message Example

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• Parse the log file, so that every message will be broken to the aforementioned 5 elements and stored as records in Lucene database

• The user can now use the efficient API of Lucene to extract information

Using Lucene for UVM Messages

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• Being designed to handle huge records, Lucene returns these records in a negligible time

– Receive all messages of a specific verbosity, or specific verbosity within some time range

– Messages containing a specific string

– All messages emitted from the APB UVC writing 0X1 to register sflash_reg.enable

Extracting UVM Records

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Agenda

• Introduction

• What is Big Data, Anyway?

• Simulation Log Files

• Graphical Representation of a Log File

• Summary

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• It is extremely hard to navigate through the log file, while seeking for the necessary information, without being overwhelmed or miss important information

• Graphical representation of data is more natural and is much easier for analysis

Why Graphical Representation?

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Graphical Representation of a Log File

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Graphical Debugging

• The transition from debugging a textual file to a graphical representation is intuitive

• Problems are traced much faster.The engineer can quickly see what is wrong, when the pattern changes, or when some unexpected event has occurred

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Agenda

• Introduction

• What is Big Data, Anyway?

• Simulation Log Files

• Graphical Representation of a Log File

• Summary

May 9, 201625

Summary

• The complexity and size of designs these days require new techniques, as the traditional ones impose very long debugging time

• Harnessing tools that are used for processing Big Data can simplify and shorten the debug time of failing tests

• We hope that this work will encourage more researches on importing these strong capabilities to the existing and new EDA tools

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Thank You

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