Guy Davidson: Linear Algebra & Jakub Beránek & Martin Hron

This time we are going to have three talks. We are going to start with the event at usual 17:00.

First talk will be Martin Hron (Avast) with talk about Spectre and Meltdown mitigation at OS level named "Fast, Furious and Wrong" (50 minutes).

Second talk will be Jakub Beránek (IT4Innovations, National Supercomputing Center) with his talk "Going down the CPU microarchitecture rabbit hole" (50 minutes).

Third talk will be from Guy Davidson (Creative Assembly, UK, member of WG21 ISO C++ committee) and he will introduce the linear algebra proposal for future C++ and he would like to discuss your opinions to make the proposal even better (90 minutes).

After talks we will move to a pub (TBA) to further networking and less formal discussions. There we can also discuss opinions about new C++ proposals and we can relay them on next WG21 meeting.

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Martin Hron: Fast, Furious and Wrong
Every programmer is furious about better performance of the code and faster CPUs. To achieve this goal we made modern CPU architectures to speculate and predict the future. But it turns out, that it comes with a cost. Did we really exchange security for speed? In this talk, I’ll try to map the landscape of known CPU vulnerabilities from the family of Meltdown and Spectre bugs. I’ll show you when the wrong speculation and prediction can have measurable side effects leading to side channel data leaks. Later I’ll show you a few examples of the issue and explain why the mitigations involve fixes from compilers, CPUs and OSes vendors. In the last part, we’ll discuss OS mitigations, why they brought a performance hit, and how are recent patches and OS updates dealing with it.

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Jakub Beránek: Going down the CPU microarchitecture rabbit hole
Modern CPU microarchitectures are extremely complex and their behaviour can sometimes cause performance degradation that cannot be explained by looking at the source code alone. In certain cases we have to look at the microarchitecture details under the hood to understand what's really going on. This presentation will attempt to explain and demonstrate several effects caused by design trade-offs in today's CPUs and also show some tools that can be used to detect and measure them.

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Jakub Beránek is a PhD student currently employed at the IT4Innovations national supercomputing center in Ostrava, where he's working on distributed programming models and task pipeline scheduling. He's also interested in improving debugging, profiling and optimization workflows and exploring CPU microarchitectures.

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Guy Davidson: Standardising A Linear Algebra Library
It is slightly curious that, twenty years after standardisation, the standard library still doesn't have support for something as fundamental as linear algebra. In this talk, after a swift refresher on the subject of linear algebra, the proposed standard will be examined and justified by one of the authors. In addition, extension and customisation methods will be presented to allow users to optimise implementations for their particular use cases.

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Principal Coding Manager of Creative Assembly, makers of the Total War franchise, Alien:Isolation and the upcoming Halo Wars sequel, Guy has been writing games since the early 1980s. He is also a voting member of the ISO C++ committee, and a contributor to SG14, the study group devoted to low latency, real time requirements, and performance/efficiency especially for Games, Financial/Banking, and Simulations. He speaks at schools, colleges and universities about programming and likes to help good programmers become better programmers.