Master's thesis presentation. Ruilin is advised by Hayden Liu Weng.
SCCS Kolloquium
The SCCS Colloquium is a forum giving students, guests, and members of the chair the opportunity to present their research insights, results, and challenges. Do you need ideas for your thesis topic? Do you want to meet your potential supervisor? Do you want to discuss your research with a diverse group of researchers, rehearse your conference talk, or simply cheer for your colleagues? Then this is the right place for you (and you are also welcome to bring your friends along).
Upcoming talks
Ruilin Qi: Comparative analysis of existing numerical linear algebra frameworks on modern architectures
SCCS Colloquium |
This thesis examines the performance of two linear algebra frameworks, PETSc and Ginkgo, on modern, heterogeneous architectures with a focus on solving large, sparse linear systems. Both libraries provide a set of Krylov subspace solvers and preconditioners with support for CPU, parallel CPU, GPU, and distributed multi-GPU execution, but differ in design, age, and supported methods. Comparable solvers are implemented in C for PETSc and C++ for Ginkgo, with testing and benchmarking being automated by bash scripts. Library performance is evaluated on a 24-core AMD EPYC CPU and four NVIDIA GeForce RTX 3080 GPUs.
Four methods are evaluated per library, with CGS, BiCGStab, and GMRES being shared, TFQMR being unique to PETSc, and IDR(s) being unique for Ginkgo. These are combined with a set of four preconditioners, Block-Jacobi, ICC, and ILU being shared, BoomerAMG for PETSc, and ISAI for Ginkgo. Test problems are taken from the SuiteSparse Matrix Collection, with sizes ranging from less than 1000 rows/columns up to larger than 1e6 rows/columns, spread. Problems were also filtered by structural properties, such as symmetry, positive definiteness, pattern symmetry, and application domain.
Performance analysis is done by considering end-to-end runtime, solve success with common convergence criteria, strong scaling for CPU and GPU configurations, and runtime comparison between CPU and GPU. Finally, a qualitative analysis is done on device load, memory throughput, and memory footprint. Results differ by library and problem size, with larger systems generally favoring GPU solves. PETSc speedups generally depend on the selected configuration of preconditioner and solver, while Ginkgo achieves a GPU speedup in almost every configuration. Further, preconditioner selection in general can significantly influence runtimes and convergence properties, with ILU and BoomerAMG being very effective preconditioners, while ICC and block-jacobi generally improve convergence less. The quantitative analysis of BiCGStab and ILU on the GPU reveals that sparse triangular solves are not well-optimized, only utilizing a fraction of available compute power.
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Contribute a talk
To register and schedule a talk, you should fill the form Colloquium Registration at least four weeks before the earliest preferred date, at the end of a semester typically even earlier reservation is necessary due to a very high influx of presentations. Keep in mind that we only have limited slots, so please plan your presentation early! In special cases, contact colloquium(at)mailsccs.in.tum.de.
Colloquium sessions are now on-campus. We have booked room MI 02.07.023 for SS25 and MI 00.13.054 for WS25/26. You can either bring your own laptop or send us the slides as a PDF ahead of time. The projector only has an HDMI connection, so please bring your own adapters if necessary.
We invite students doing their Bachelor's or Master's thesis, as well as IDP, Guided Research, or similar projects at SCCS to give one 20min presentation to discuss their results and potential future work. The time for this is typically after submitting your final text. Check also with your study program regarding any requirements for a final presentation of your project work.
New: In regular times, we will now have slots for presenting early stage projects (talk time 2-10min). This is an optional opportunity for getting additional feedback early and there is no strict timeline.
Apart from students, we also welcome doctoral candidates and guests to present their projects.
During the colloquium, things usually go as follows:
- 10min before the colloquium starts, the speakers setup their equipment with the help of the moderator. The moderator currently is Ana Cukarska. Make sure to be using an easily identifiable name in the online session's waiting room.
- The colloquium starts with an introduction to the agenda and the moderator asks the speaker's advisor/host to put the talk into context.
- Your talk starts. The scheduled time for your talk is normally 20min with additional 5-10min for discussion.
- During the discussion session, the audience can ask questions, which are meant for clarification or for putting the talk into context. The audience can also ask questions in the chat.
- Congratulations! Your talk is over and it's now time to celebrate! Have you already tried the parabolic slides that bring you from the third floor to the Magistrale?
Do you remember a talk that made you feel very happy for attending? Do you also remember a talk that confused you? What made these two experiences different?
Here are a few things to check if you want to improve your presentation:
- What is the main idea that you want people to remember after your presentation? Do you make it crystal-clear? How quickly are you arriving to it?
- Which aspects of your work can you cover in the given time frame, with a reasonable pace and good depth?
- What can you leave out (but maybe have as back-up slides) to not confuse or overwhelm the audience?
- How are you investing the crucial first two minutes of your presentation?
- How much content do you have on your slides? Is all of it important? Will the audience know which part of a slide to look at? Will somebody from the last row be able to read the content? Will somebody with limited experience in your field have time to understand what is going on?
- Are the figures clear? Are you explaining the axes or any other features clearly?
In any case, make sure to start preparing your talk early enough so that you can potentially discuss it, rehearse it, and improve it.
Here are a few good videos to find out more:
- Simon Peyton Jones: How to Give a Great Research Talk (see also How to Write a Great Research Paper)
- Susan McConnell: Designing effective scientific presentations
- Jens Weller: Presenting Code
Did you know that the TUM English Writing Center can also help you with writing good slides?
Work with us!
Do your thesis/student project in Informatics / Mathematics / Physics: Student Projects at the SCCS.