Winter 2015 SPO600 Weekly Schedule
It contains historical information. For current information, please see Current SPO600 Weekly Schedule.
Schedule Summary Table
This is a summary/index table. Please follow the links in each cell for additional detail -- especially for the Deliverables column.
Evaluation
| Category | Percentage | Evaluation Dates |
|---|---|---|
| Communication | 20% | January 31, February 28, March 27, April 22 |
| Quizzes | 10% | May be held during any class, usually at the start of class. A minimum of 5 one-page quizzes will be given. No make-up/retake option is offered if you miss a quiz. Lowest 3 scores will not be counted. |
| Labs | 10% | See deliverables column above. |
| Project work | 60% | March 16 (15%), March 31 (20%), April 22 (25%) |
Week 1
Tuesday (Jan 13)
Introduction to the Problems
Porting and Portability
- Most software is written in a high-level language which can be compiled into machine code for a specific computer architecture. In many cases, this code can be compiled for multiple architectures. However, there is a lot of existing code that contains some architecture-specific code fragments written in Assembly Language (or, in some cases, machine-specific high-level code).
- Reasons for writing code in Assembly Langauge include:
- Performance
- Atomic Operations
- Direct access to hardware features, e.g., CPUID registers
- Most of the historical reasons for including assembler are no longer valid. Modern compilers can out-perform most hand-optimized assembly code, atomic operations can be handled by libraries or compiler intrinsics, and most hardware access should be performed through the operating system or appropriate libraries.
- A new architecture has appeared: Aarch64, which is part of ARMv8. This is the first new computer architecture to appear in several years (at least, the first mainstream computer architecture).
- At this point, most key open source software (the software typically present in a Linux distribution such as Ubuntu or Fedora, for example) now runs on AArch64. However, it may not run as well as on older architectures (such as x86_64).
Benchmarking and Profiling
Benchmarking involves testing software performance under controlled conditions so that the performance can be compared to other software, the same software operating on other types of computers, or so that the impact of a change to the software can be gauged.
Profiling is the process of analyzing software performance on finer scale, determining resource usage per program part (typically per function/method). This can identify software bottlenecks and potential targets for optimization.
Optimization
Optimization is the process of evaluating different ways that software can be written or built and selecting the option that has the best performance tradeoffs.
Optimization may involve substituting software algorithms, altering the sequence of operations, using architecture-specific code, or altering the build process. It is important to ensure that the optimized software produces correct results and does not cause an unacceptable performance regression for other use-cases, system configurations, operating systems, or architectures.
The definition of "performance" varies according to the target system and the operating goals. For example, in some contexts, low memory or storage usage is important; in other cases, fast operation; and in other cases, low CPU utilization or long battery life may be the most important factor. It is often possible to trade off performance in one area for another; using a lookup table, for example, can reduce CPU utilization and improve battery life in some algorithms, in return for increased memory consumption.
Most advanced compilers perform some level of optimization, and the options selected for compilation can have a significant effect on the trade-offs made by the compiler, affecting memory usage, execution speed, executable size, power consumption, and debuggability.
Build Process
Building software is a complex task that many developers gloss over. The simple act of compiling a program invokes a process with five or more stages, including pre-proccessing, compiling, optimizing, assembling, and linking. However, a complex software system will have hundreds or even thousands of source files, as well as dozens or hundreds of build configuration options, auto configuration scripts (cmake, autotools), build scripts (such as Makefiles) to coordinate the process, test suites, and more.
The build process varies significantly between software packages. Most software distribution projects (including Linux distributions such as Ubuntu and Fedora) use a packaging system that further wraps the build process in a standardized script format, so that different software packages can be built using a consistent process.
In order to get consistent and comparable benchmark results, you need to ensure that the software is being built in a consistent way. Altering the build process is one way of optimizing software.
Note that the build time for a complex package can range up to hours or even days!
Course Projects
In this course, you will:
- Test the performance of all or part of the LAMP stack.
- Determine how the performance of one specific part of the stack could be improved, either specifically on AArch64 systems (without detriment to other systems) or on all systems.
- Prepare a fix/patch for the software to implement that performance improvement.
- Prove that your changes do not cause any unacceptable performance regressions (Note: there might be performance regressions which are considered acceptable!).
- Upstream your Code - Submit your code to the upstream (originating) software project so that it can be incorporated into future versions of the software. This will involve going through a code review to ensure that your code is compatible with and acceptable to the upstream community.
General Course Information
- Course resources are linked from the CDOT wiki, starting at http://zenit.senecac.on.ca/wiki/index.php/SPO600 (Quick find: This page will usually be Google's top result for a search on "SPO600").
- Coursework is submitted by blogging.
- Quizzes will be short (1 page) and will be held without announcement at any time. Your lowest three quiz scores will not be counted, so do not worry if you miss one or two.
- Course marks (see Weekly Schedule for dates):
- 60% - Project Deliverables
- 20% - Communication (Blog and Wiki writing)
- 20% - Labs and Quizzes (10% labs - completed/not completed; 10% for quizzes - lowest 3 scores not counted)
- All classes will be held in an Active Learning Classroom -- you are encouraged to bring your own laptop to class. If you do not have a laptop, consider signing one out of the Learning Commons for class, or using a smartphone with an HDMI adapter.
- For more course information, refer to the SPO600 Weekly Schedule (this page), the Course Outline, and SPO600 Course Policies.
Discussion of how open source communities work
- Background for the Code Review Lab (Lab 1).
Thursday (Jan 15)
- Benchmarking
- Profiling
Week 1 Deliverables
- Set up your SPO600 Communication Tools - in particular, set up a blog and add it to Planet CDOT (via the Planet CDOT Feed List).
- Add yourself to the Winter 2015 SPO600 Participants page (leave the projects columns blank).
- Generate a pair of keys for SSH and email the public key to your professor.
- Sign and return the Open Source Professional Option Student Agreement.
- Optional but recommended: Set up a personal Fedora system.
Week 2
Tuesday (Jan 20)
Classes are held in a Active Learning Classroom. If you have a laptop or other device with a VGA or HDMI output (such as a smartphone!) please bring it. You'll need either a local linux environment or an SSH client -- which is built-in to Linux, Mac, and Chromebook systems, and readily available for Windows, Android, and iOS devices.
Status Check
- Introductions around the Room
- Name
- Program
- Interest in the course
- Results of
gzipbenchmarking and most interesting thing you observed
- Check the server accounts that were set up with your SSH keys
- Sheets from Last Week
- Open Source Student Agreement
- Survey (Optional)
Working with the Code
- Getting Code
- In a tarball
- From git
- Git basics
- Working with other version control systems
- Building the Code
- Make
- Configuration tools (autotools, cmake)
- The compiler toolchain
- Preprocessor
- Compiler
- Assembler
- Linker
- Debug vs. Non-debug/Stripped binaries
Looking at How Distributions Package the Code
- Using fedpkg
Resources
Thursday (Jan 22)
Week 2 Deliverables
- Complete and blog your conclusion to the Code Review Lab (Lab 1).
- Blog your baseline data from the Baseline Builds and Benchmarking lab (Lab 2).
Week 3
Tuesday (Jan 27)
Profiling
- Profiling with
gprof- Build with profiling enabled (use the option
-pgwith both gcc and ld) - Run the profile-enabled executable
- Analyze the data in the
gmon.outfile-
gprof nameOfBinary# Displays text profile including call graph -
gprof nameOfBinary | gprof2dot | dot | display -# Displays visualization of call graph
-
- Build with profiling enabled (use the option
- Other profiling tools
- OProf, SystemTap, and others
- SPO600 Profiling Lab (Lab 3)
Thursday (Jan 29)
- Computer Architecture overview (see also the Computer Architecture Category)
Week 3 Deliverables
- Complete and blog your conclusions to the Profiling Lab (Lab 3).
Week 4
Tuesday (Feb 3)
Thursday (Feb 5)
Week 4 Deliverables
- Blog your Compiled C Lab (Lab 4) results. Be sure to include a reflective section on what you learned.
- Select your topic for the Platform-Specific Code Presentation.
Week 5
Week 6
Tuesday (Feb 17)
- Introduction to the HiKey board and the 96Boards project.
- Presentations on platform-specific code
Thursday (Feb 19)
Week 6 Deliverables
- Blog about your presentation.
Week 7
Tuesday (Feb 24)
Thursday (Feb 26)
Week 7 Deliverables
- Blog your conclusion to the assembly language lab (Lab 5) - See the Deliverables section in the lab instructions for details on what to include in your blog post.
Week 8
Tuesday (Mar 10)
- Project discussion
- Discussion of project ideas and fine-tuning of project plans
- Next steps
- Addressing Problem Areas
- Accessing and Reading Reference Documentation
- AArch64 ISA
Thursday (Mar 12)
- Project presentations
- Provide a very short (2 minute) overview of your project. Include:
- Which piece of software you are working on
- What area of that software needs optimization/performance tuning
- How you are going to perform the optimization/tuning (algorithm replacement, platform-specific code, removing platform-specific code, build options, and so forth)
- Plans for the next step
- Engagement with the upstream community
- Provide a very short (2 minute) overview of your project. Include:
- Use this project presentation to tell the class what you're working on and incorporate feedback into your blog post
Week 8 Deliverables
- Blog about your project and plans, incorporating feedback from your presentation
- Add your project to the Participants and Project Table.
Week 9
Tuesday (Mar 17)
- Upstreaming
- Git Discussion
- Creating a Patch
- Various open source community workflows
Thursday (Mar 19)
- Spinlocks
- The need for Atomics in Spinlocks
- Using Intrinsics for Atomic Operations
- Tail Call Optimization (TCO)
- gcc will perform TCO at -O2 and higher
- Important to ensure that gcc recognizes code patterns that permit TCO to be applied
Week 9 Deliverables
- Blog at least once (and ideally more than once) about your Project
- Frequent shorter posts are better than rare long ones
- Aim to make steady progress on your project, a bit each day
- Blog about your evolving project plan and the steps you're making along the way
- Keep the work short, and focus on narrowing the scope of work as early as possible
- Keep talking to the community
Week 10
Tuesday (Mar 24)
- Discussion of GCC Intrinsics
- Where to find documentation: GCC Manual
- __atomic vs __sync intrinsic families
- Examination of Build Files
- Differential analysis of successful and unsuccessfull build
Thursday (Mar 26)
- Project Presentations - Stage 2
- At this point, you should have a proposed patch that you're working to get upstream
Week 10 Deliverables
- Blog posts about your project
- Include information about your patch(es)
- Include links to discussion about the patch(es) with the community (e.g., link to bug/issue tracker entries or email archives)
- If you don't have patches and/or have not pushed them upstream yet, describe the state of your project and your plan to get changes upstream.
- Blogs will be marked Monday for Stage 2 project work (20%)
Week 11
Tuesday (Mar 31)
Your professor will be away. You are welcome to use the classroom for a project hacking time and collaboration with your colleagues.
Thursday (Apr 2)
- Single Instruction / Multiple Data (SIMD)
- Brief look at x86_64 & AArch64 implementations of SIMD
Week 11 Deliverables
- Blog about your ongoing project work. Please post at least 1-2 entries per week.
Week 12
Tuesday (Apr 7)
- Discussion & Hacking Session
Thursday (Apr 9)
- Vectorization
- Using Intrinsics
- Using Auto-Vectorization
Week 12 Deliverables
- Blog about your ongoing project work. Please post at least 1-2 entries per week.
- You should have patches (code, makefiles, documentation, or tests) in the upstream review process at or before this point.
- Blog about vectorization - specifically:
- What -O level and/or options are needed to turn on the auto-vectorizer in GCC
- At least three limitations -- conditions under which the vectorization will not be performed
- The significance of alignment and non-overlapping pointers for vectorization
Week 13
Tuesday (Apr 14)
- Informal Project Presentations - Phase 3
Thursday (Apr 16)
- Wrap-up Session
Week 13 Deliverables
- Blog about your ongoing project work. Your patches should be through the upstream review process.
- Final date for posting about your project: April 22.