2007 Tidc India Profiling

XDS560 Trace Daniel Rinkes Texas Instruments [email_address] Advanced Use Cases for Profiling

Agenda AET / XDS560Trace Overview Interrupt Profiling Statistical Profiling Thread Aware Profiling Thread Aware Dynamic Call Graph

What is AET / XDS560 Trace XDS560 Trace Allows Cycle Accurate Logging of CPU Address Bus and Data Bus Activity Non-Intrusively, in Real Time Advanced Event Triggering (AET) is logic that allows us to smartly turn trace on in interesting locations and off in non-interesting locations so as to preserve the trace buffer for interesting data

XDS560 Trace Architecture Additional JTAG Emulation Pins DATA ADDRESS BUSSES DATA BUSSES PROGRAM BUS DSP XDS560T POD CPU XDS560T POD RECORDING UNIT Current Buffer Size: 224K Future: 64 MB To/from host PC Trace & AET Jobs Comparators Compressor Cycle counter

Required Software and Hardware 60 Pin emulation header Target must support Trace (Full-Gem) Blackhawk USB 560 XDS560T Trace Pod/Cable CCS 3.30 or higher

64x+ Device Support For Trace SUPPORT TRACE C6455 C6488 DM647/DM648 DO NOT SUPPORT TRACE DM6443/DM6446 Any LC Device

Interrupt Profiling Overview Capture Program Address and Timestamp whenever the PC is within the Interrupt Vector Table Generate a cycle accurate picture of when each interrupt starts executing Graphically display interrupt cycle accurate interrupt servicing frequency

102462 102463 Cycle Count 102456 102457 102458 102459 102460 102461 Trace Log PC Cycles 0x00897C68 102458 0x00897C64 102457 0x00897C6C 102459 0x00897C70 102460 0x00897C74 102461 0x00897C78 102462 0x00897C7C 102463 0x00897C60 102456

Data Captured Raw Trace Data Processed Data

Statistical Profiling GOAL Get a quick overall view of which functions in an application consume the most cycles Sampling every Program Counter in an application quickly consumes Trace Buffer Bandwidth, preventing analysis of the entire application We can eliminate this problem by only capturing a statistical sample of application execution

Statistical Profiling Overview The Program Address is sampled at regular intervals Statistical Analysis is performed on the captured samples As in any statistical analysis, the determinations made on the statistical sample can be related to the general population

Statistical Profiling - 2 AET contains all of the hardware needed to capture trace samples at a specified interval Interval should be carefully chose so as not to coincide with a periodic function Application instrumentation can switch AET off in locations that are not of interest

Statistical Profiling - Results Comma Separated Value Format Sorted from most intensive functions to least

Thread Aware Profiling GOAL Generate a cycle accurate execution graph of a Thread/Task based application

Solution Instrument the task/thread switch function to write the task/thread ID to a well known location (global variable) Operating systems typically provide hooks to insert functions in this location Trace all of the writes to that location, and get a timestamp with each.

Thread Aware Dynamic Call Graph GOAL Display a Thread Based representation of actual function execution in an application

Capturing the Data Thread/Task Hook function writes address of task Function Entry/Exit points instrumented with Mark 0/ Mark 1 instructions* Mark 0 inlined at each function entry point Mark 1 inlined at each function exit point Trace captures each of these locations with timestamp * CGT 6.0.1 enables function hooks

Presentation Graphical Displays become impractical as the number of functions increase At right is a sample call graph displayed by the Guess graphing package

GPROF Like Format Modeled after Unix GPROF Each Thread separated into it’s own subsection Each function section contains only immediate callers and callees

A Closer Look Primary Line - describes the function which the entry is about and gives the overall statistics for this function Lines for a Functions Callers Lines for a Functions Callees

Future Display – Tree View Thread: 0x828194 _DEC_tcp2DeintUnpunctsoft3 _DEC_tcp2QuantizeSoft _DEC_tcp2PreProc _varianceEstim _COM_spoolTsk _COM_spoolPost _DEC_tcp2EdmaIsr _DEC_tcp2DeintUnpunctsoft3 Callers Callees _DEC_tcp2DeintUnpunctsoft3 Callers _DEC_tcp2PreProc Calls = 388/388 Exclusive Cycles = 14491050

Comparison vs. Traditional The Results of the statistical profile tend to approximate those found using traditional profiling.

Advanced Event Triggering Overview

Use Case Examples Simple Read/Write Data Location Read/Write Data Range Specific Value Read/Write to/from Specific Location Medium Read/Write to location A, but only after executing instruction B Complex Read/Write to location A, but only after executing instruction B at least 20 times CPU Halt Interrupt Start/Advance Counter Stop/Reload Counter Start Trace Store Trace Sample End Trace External Trigger (EMU 0/1) State Transition

AET Target LIbrary What is it? A Target Library to allow programming of AET resources from the target application Advantages over CCS AET Plug-in? Context based control of where AET is enabled/disabled Ability to reallocate AET resources on the fly Some functionality not inherently contained in the plug-in Disadvantages Some Application cycles consumed Some Application footprint used

Use Case Consider: Thread based application crashing because of a suspected overflow of one of the task stacks. Would like to use AET to monitor the top of the task stacks and generate an interrupt when we get too close to the top Problems All of the threads are dynamically created at run time, so there’s no way to know where the top of the dynamically allocated stack will be located at load time. There are numerous threads, and AET resources are consumed by ONE “Watchpoint In Range” job

Solution Use the AET Target Library All Operating Systems (DSP/Bios, OSE, etc) have a thread switch function that occurs when switching tasks. The user can place code in this hook that gets executed every time a thread switches context. In this function, program AET to watch the top of the stack of the NEXT thread. Every subsequent time that the thread is switched, delete the old AET job, and program a new one.

Solution - 2 What does this accomplish? Reuse of resources By removing the prior AET job, you are reclaiming the resources (trigger builder and comparators) that were used. Additionally, AET is only watching the CURRENT stack at a given time. Thus we’re able to manage with the 4 data comparators that are available. Dynamic Task Location By programming AET at run time, we can know where the dynamically allocated tasks are placing their stack. This method also works perfectly well for statically allocated tasks.

2007 Tidc India Profiling

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2007 Tidc India Profiling