Meta Chips – Colvore water-cooling – Google AI TPv4 – NCCL – PINS P4 – Slingshot – KUtrace

Read 1. Meta to build its own AI chips. Currently using 16k A100 GPU (Google using 26k H100 GPU). And it seems Graphcore had some issues in 2020.

Read 2. Didnt know Colovore, interesting to see how critical is actually power/cooling with all the hype in AI and power constrains in key regions (Ashburn VA…) And with proper water cooling you can have a 200kw rack! And seems they have the same power as a 6x bigger facility. Cost of cooling via water is cheaper than air-cooled.

Read 3. Google one of biggest NVIDIA GPU customer although they built TPUv4. MS uses 10k A100 GPU for training GPT4. 25k for GPT5 (mix of A100 and H100?) For customer, MS offers AI supercomputer based on H100, 400G infiniband quantum2 switches and ConnectX-7 NICs: 4k GPU. Google has A3 GPU instanced treated like supercomputers and uses “Apollo” optical circuit switching (OCS). “The OCS layer replaces the spine layer in a leaf/spine Clos topology” -> interesting to see what that means and looks like. As well, it uses NVSwitch for interconnect the GPUs memories to act like one. As well, they have their own (smart) NICS (DPU data processing units or infrastructure processing units IPU?) using P4. Google has its own “inter-server GPU communication stack” as well as NCCL optimizations (2016! post).

Read4: Via the P4 newletter. Since Intel bought Barefoot, I kind of assumed the product was nearly dead but visiting the page and checking this slides, it seems “alive”. Sonic+P4 are main players in Google SDN.

 “Google has pioneered Software-Defined Networking (SDN) in data centers for over a decade. With the open sourcing of PINS (P4 Integrated Network Stack) two years ago, Google has ushered in a new model to remotely configure network switches. PINS brings in a P4Runtime application container to the SONiC architecture and supports extensions that make it easier for operators to realize the benefits of SDN. We look forward to enhancing the PINS capabilities and continue to support the P4 community in the future”

Read5: Slingshot is another switching technology coming from Cray supercomputers and trying to compete with Infiniband. A 2019 link that looks interesting too. Paper that I dont thik I will be able to read neither understand.

Read6: ISC High Performance 2023. I need to try to attend one of these events in the future. There are two interesting talks although I doubt they will provide any online video or slides.

Talk1: Intro to Networking Technologies for HPC: “InfiniBand (IB), High-speed Ethernet (HSE), RoCE, Omni-Path, EFA, Tofu, and Slingshot technologies are generating a lot of excitement towards building next generation High-End Computing (HEC) systems including clusters, datacenters, file systems, storage, cloud computing and Big Data (Hadoop, Spark, HBase and Memcached) environments. This tutorial will provide an overview of these emerging technologies, their offered architectural features, their current market standing, and their suitability for designing HEC systems. It will start with a brief overview of IB, HSE, RoCE, Omni-Path, EFA, Tofu, and Slingshot. In-depth overview of the architectural features of IB, HSE (including iWARP and RoCE), and Omni-Path, their similarities and differences, and the associated protocols will be presented. An overview of the emerging NVLink, NVLink2, NVSwitch, Slingshot, Tofu architectures will also be given. Next, an overview of the OpenFabrics stack which encapsulates IB, HSE, and RoCE (v1/v2) in a unified manner will be presented. An overview of libfabrics stack will also be provided. Hardware/software solutions and the market trends behind these networking technologies will be highlighted. Sample performance numbers of these technologies and protocols for different environments will be presented. Finally, hands-on exercises will be carried out for the attendees to gain first-hand experience of running experiments with high-performance networks”

Talk2: State-of-the-Art High Performance MPI Libraries and Slingshot Networking: “Many top supercomputers utilize InfiniBand networking across nodes to scale out performance. Underlying interconnect technology is a critical component in achieving high performance, low latency and high throughput, at scale on next-generation exascale systems. The deployment of Slingshot networking for new exascale systems such as Frontier at OLCF and the upcoming El-Capitan at LLNL pose several challenges. State-of-the-art MPI libraries for GPU-aware and CPU-based communication should adapt to be optimized for Slingshot networking, particularly with support for the underlying HPE Cray fabric and adapter to have functionality over the Slingshot-11 interconnect. This poses a need for a thorough evaluation and understanding of slingshot networking with regards to MPI-level performance in order to provide efficient performance and scalability on exascale systems. In this work, we delve into a comprehensive evaluation on Slingshot-10 and Slingshot-11 networking with state-of-the-art MPI libraries and delve into the challenges this newer ecosystem poses.”

Read7: Slides and Video. I was aware of Dtrace (although never used it) so not sure how to compare with KUtrace. I guess I will ask Chat-GPT 🙂

Read8: Python as programming of choice for AI, ML, etc.

Read9: M$ “buying” energy from fusion reactors.

Mobile Phone + SSH server

I have tried many times to connect my mobile phones to my laptop. It always looks easy if you use M$ but with Linux I always fail, I can’t get to work MTP. So now I really want to take mainly all my pictures from a phone and be able to back them up and transfer to a new one. I dont want to use cloud services or tools from the manufacturers. I want to use old school methods. So after struggling for some time, I somehow decided to use something as old school as SSH/SCP. Android is based in linux, isn’t it? So I searched for a free SSH server app, found this one. And it worked! I managed to understand it, created my user, my mounting points, enable it… and was able to SCP all my photos from my mobile to my laptop. It worked with Samsung and Huawei.

I am pretty sure that people know have better ways to do this… but that’s me.

Chocolate Fondant

Based on this video:


  • 130g dark chocolate (+70%)
  • 130g butter + extra for greasing
  • 3 eggs
  • 1 egg yolk
  • 100g caster sugar
  • 70g plain flour
  • 15g cocoa powder + extra for dusting
  • 2.5g baking powder
  • 4 aluminium moulds


  • Pre-heat oven at 180C
  • Melt chocolate and butter at “baine marie”. Let it cool down a bit to use later.
  • Grease with butter the moulds and dust the sides with cocoa powder
  • Make the “raw sabayon”: whisk the eggs and sugar until pale in color.
  • Fold the chocolate (be sure it is not too hot) into the sabayon. Be sure the mix is uniform and there are no lumps.
  • Sieve flour, cocoa and baking powder. Then add to the mix bit by bit, folding with a spatula and checking there are no lumps.
  • Fill the moulds at 90% aprox. They will raise in the oven
  • Bake the moulds at 180C for 9 minutes aprox.
  • Use a tooth stick to be sure they are still creamy inside. The idea is the chocolate should come out once opened.
  • Unmould and present on a plate with a bit of fresh mint, strawberries. Dust with a bit of icing sugar.
  • Be sure you serve it hot! (optionally you can add a ball of vanilla ice cream).

No free lunch

Just a reminder

“Every single pursuit – no matter how wonderful and exciting and glamorous it may initially seem – comes with its own brand of shit sandwich, its own lousy side effects. Everything sucks some of the time. You just have to decide what sort of suckage you’re willing to deal with.
So the question is not so much ‘What are you passionate about?’
The question is ‘What are you passionate enough about that you can endure the most disagreeable aspects of the work?’
Because if you love something and want something enough – whatever it is – then you don’t really mind eating the shit sandwich that comes with it.”
- Mark Manson
In a world of comfort one question the most important question to ask yourself is what are you willing to struggle for? You can have the pain of being lazy or the pain of putting an effort into your health and body? Which one will it be?