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|5||Feb 3||[[#Tuesday (Feb 4)|Memory Barriers and Atomics]]||[[#Friday (Feb 7)|Potential Project Analysis]]||[[#Week 5 Deliverables|Blog about your selected projects]]
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|6||Feb 10||[[#Tuesday (Feb 11)|Platform-specific Code for Performance]]||Porting - Adding platform-specific code for Aarch64||Group hack session - Porting||Port [[#Week 5 Deliverables|Identify the assembler in your projectsand contact your upstream communities.]]
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|7||Feb 17||Portability - Removing platform-specific code||Group hack session - Portability||Remove platform-specific code from your projects
** You may want to break this into a couple of posts - e.g., post about your first package while you're working on your second.
** Feel free to also blog about why you did '''not''' choose particular packages, too.
== Week 6 ==
=== Tuesday (Feb 11) ===
* Architecture-specific code for Performance
** Sometimes assembler is used in a C/C++ program for performance. However, modern versions of C/C++ (such as C++11) and recent compilers provide portable ways of accessing high-performance processor capabilities, such as Single Instruction/Multiple Data (SIMD) instructions (called "marketing names" such as SSE, Neon, MMX, 3DNow, or AltaVec on various processors).
** Linaro enginener Matthew Gretton-Dann gave a good presentation on [http://www.linaro.org/linaro-blog/2013/09/20/introduction-to-porting-and-optimising-code/ Porting and Optimizing Code] for aarch64. The vectorization portion, beginning at 28:10, provides a good introduction to SIMD and autovectorization using GCC on aarch64 (Note that the earlier portion of the presentation includes good information about Atomics).
*** [http://www.youtube.com/watch?v=epzYErIIx0Y YouTube Video] direct link
*** [http://www.linaro.org/assets/common/campus-party-presentation-Sept_2013.pdf Slides] direct link
** Note that in the presentation above, Matthew takes the code beyond portability without straying into assembler (e.g., using compiler-specific, architecture-specific intrinsics). It is possible to achieve almost all of the performance gains without becoming arch-specific, and most of those can be attained without becoming compiler-specific as well.
* For full details on the SIMD instructions in aarch64, refer to the [http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.genc010197a/index.html ARMv8 Instruction Set Overview], particularly section 5.7.
=== Week 6 Deliverables ===
* Complete your analysis of your two selected software projects (if you haven't already) - see [[#Week 5|Week 5]]. Blog in detail about your findings.
* Identify the upstream communities that develop and maintain the software you have selected to work on. Figure out how they are structured, how they communicate, how code is maintained, and how patches are accepted. Introduce yourself to each of the two communities (one for each of the two software projects you have selected). Blog about your findings.
