The other day, I checked out the web interface to the database of in-patient care diagnoses run by Swedish Socialstyrelsen. On first opening the site, it looked broken and unusable – the text was basically unreadable, mixing giant numbers with strange- looking regular characters, lines of text overlapping each other, and a general sense of being totally chaotic. That is not what you or I would expect from an official site of a government entity. They have no reason to play games with the look of the site. So how come it was all that broken? Didn’t they test the site properly under all circumstances?Continue reading “Testing what the User will See (and why it might not work out)”
I recently read a few articles on cognitive biases, decision making, and expert intuition from the field of management research. Then an article popped up from the Communications of the ACM (CACM) dealing with cognitive bias in software development. The CACM article is a small field study that serves up some interesting and potentially quite useful conclusions about how to think about thinking in software development.Continue reading “A Study of Cognitive Biases in Software Development”
A colleague pointed me at the grugbrain.dev website the other week. It is a very humorous set of observations on corporate life and advice to young developers – written in a silly “cave-man” style. It is obviously based on long experience. The text is also quite quote-worthy, with some passages even being quite poetic in their rough-hewn simplicity.Continue reading “Blog: Grug Brained Developer Make Sense “
The 59th Design Automation Conference (DAC) took place in San Francisco, July 10-14, 2022. As always, the DAC provided a great place to learn about what is going on in EDA. The DAC is really three events in one: there is an industry trade-show/exhibition, a research conference that is considered the premier in EDA, and an engineering track where practitioners present their work in a less formal setting.
I had two talks in the engineering track – one on the Intel device modeling language (which actually won the best presentation award in the embedded sub-track), and one on using simulation technology to build hardware software-first.
The DAC was almost overwhelming in the richness of people and companies, but this blog tries to summarize the most prominent observations.Continue reading “DAC 2022 – Back in Person, Chiplets, an Award, and Much More”
I recently published a long post on the Intel Community Blog, talking about how my colleague Evgeny solved a nicely complicated bug using Simics-on-Simics. The bug involved UEFI, an operating system, SMM, SMI, and virtualization. Just another day in the office (or more like a year, given how long it took to get this one resolved).
Back in 2016, the European Space Agency (ESA) lost the Schiaparelli Mars lander during its descent to the surface on Mars. From a software engineering and testing perspective, the story of why the landing failed (see for example the ESA final analysis, Space News, or the BBC) is instructive. It comes down to how software is written and tested to deal with unexpected inputs in unexpected circumstances. I published a blog post about this right after the event and before the final analysis was available. Thankfully, that has since been retired from its original location-it was a bit too full of speculation that turned out to be incorrect… So here is a mostly rewritten version of the post, quoting the final analysis and with new insights.Continue reading “The ESA Schiaparelli Crash & Simulation”
Back in April, I presented a talk about how you can use Lego as an analogy for software development in the ProductBeats Show. The talk was based on my previous musings about Lego and software. It was a great fun 15 minutes with a good after-discussion moderated by Magnus Billgren. As always at the ProductBeats show, Magnus nudged me and the audience to think. He kicked off the talk by asking the audience and me about the process of assembling IKEA furniture. Is that assembly about building or designing? That is a very god question. Here is my attempt at an answer.Continue reading “Building or Designing, Lego and IKEA”
I recently made a trip to the US to look at some interesting things like the USS Intrepid, the architecture or New York City, and Battleship Cove. Battleship Cove is located in Fall River, Massachusetts, and hosts the South Dakota-class battleship USS Massachusetts. Additionally, the site holds the destroyer USS Joseph P Kennedy, the submarine USS Lionfish, and the East German missile corvette Hiddensee. Given that I only had an afternoon there, I ended up only looking at the battleship with a brief run through the submarine. It was that good, especially in company with an old friend who also had read up on how the ship worked.Continue reading “USS Massachusetts and Battleship Cove”
Today I observed something very odd in Powerpoint. I was pasting in some text from the Simics command-line interface into a text box in Powerpoint to show the output of some commands. Commands whose output relied on box-drawing characters to produce nice tables. But for some reason… it did not work in Powerpoint. Weird.Continue reading “Was this a UTF-8 WTF?”
The SystemC Evolution Fika on April 7 had threading/parallelism as its theme. There were four speakers who presented various angles on how to parallelize SystemC models. The presentations and following discussion provided a variety of perspectives on threading as it can be applied in virtual platforms and other computer architecture simulations. It was pretty clear that the presenters and audience had quite different ideas about just what the target domain looks like and the best way to introduce parallelism to SystemC. Here is my take on what was said.Continue reading “SystemC Evolution Fika: Parallel SystemC”
This blog post was originally posted at Intel back in 2018, but it has since been retired from the Intel blog system. As it is of general interest (in my opinion), here is a reposting (with a few small updates here and there).
Temporal decoupling is a key technology in virtual platforms, and can speed up the execution of a system by several orders of magnitude. In my own experiments, I have seen it provide a speedup of more than 1000x. Here, I will dig a little deeper into temporal decoupling and its semantic effects.Continue reading “Some Notes on Temporal Decoupling (Reposted)”
The Design and Verification Conference (DVCon) Europe is going to be in-person in München again in 2022. After two years of virtual conferences, we are going back to the Holiday Inn where we have had so many great events in the past. The conference takes place on December 6 and 7. The call for papers, tutorials, and panels is out now, with a deadline in May!Continue reading “DVCon Europe 2022 – Come Join us in München in December”
In a previous blog, I talked a bit about the hazards of coding to an implementation and not a specification, based on 1980s home computers. While the specifics and peculiarities of that case is hopefully confined to old hardware, the lessons are still worth contemplating. There is a modern variant of this phenomenon that is based on open-source software, and that I must admit to feeling a bit annoyed by. Fundamentally, the question is this: when figuring out how to use an API – should you look at the documentation or the implementation?Continue reading “Don’t Look behind the Curtain! (Please)”
When discussing the design and integration of systems on chip and models of systems on chip, the Lego analogy is often brought up. The idea being that with Lego, anyone can put together anything and every component can be combined with all other components. Right. My recent building of Lego set 21327, Typewriter, makes me wonder if the people who talk about Lego-like construction have actually built anything from Legos in the past few decades.Continue reading “Easy to Assemble, just like Lego – Right…”
I have recently got back to developing training labs for the Simics simulator (and related technologies). During the process of developing a new accelerator model using as many of the latest frameworks and APIs as possible, it was basically guaranteed that I would hit some bugs and unexpected behaviors. That is a natural part of and benefit from creating training materials in the first place. It also provides a good illustration of two fundamentally different ways to look at software development. One is to play it safe and get things done in known ways, and the other is charge ahead, try the unknown, and see what happens. Damn the torpedoes, bugs are a benefit. No bug reports, no glory. In this post, I will share some recent examples of just coding ahead and breaking thing.Continue reading “Blog – Damn the Torpedoes, Full Code Ahead!”
During 2020 and 2021, Intel switched from using Microsoft Skype for Business (also known as Lync) to Microsoft Teams as the primary internal calling, chatting, and conferencing tool. While (finally) Teams has turned into quite a decent communications tool, the transition started a bit too early from a feature completeness perspective. Microsoft in essence gave us an enterprise Minimum Viable Product (MVP). Not a proper Replacement Product (RP). Teams left out many rather important and useful features, degrading the user experience and value, and making my life harder. I don’t think that was particularly well handled. I can understand it as a product manager, but as a user, I don’t like it all.Continue reading “Minimum Viable (Replacement) Product – The Teams Example”
Just like in 2020, the Design and Verification Conference (DVCon) Europe 2021 was a virtual conference. It took place from October 26 to 27, with the SystemC Evolution day on October 28 (as usual). As has been the case in recent years, the verification side of the conference is significantly larger than the design side. This is common with the other DVCon conferences in the world. In this blog, I will go through my main observations from DVCon Europe, and share some notes from some of the presentations.Continue reading “DVCon Europe 2021 – Testbenches, AI, and Open Source”
When writing software that uses any kind of API or hardware functionality, sooner or later there will be questions about what a particular API call or hardware operation is supposed to do. In principle, such questions should be answered by referring to the specification (and user documentation). I am a firm believer in writing readable and clear specs and keeping software coding to follow the spec, as that ensures future compatibility. But reality is not that simple. Things are generally better today than they used to be, though. Reading up a bit on the history of my first computer (the ZX Spectrum), I found some rather interesting cases of spec vs implementation, and “discovered functionality”.Continue reading “Code to the Spec(trum) or the Implementation”
DVCon Europe is coming up in late October. This year, I am going to present a tutorial on using the public release of the Intel Simics Simulator to model a PCIe-attached accelerator subsystem. It is fun to be back speaking at the DVCon, after a couple of years of not having talked at the conference. DVCon Europe is a virtual event this year too due to Covid.Continue reading “Presenting a Simics Tutorial at DVCon Europe (2021)”
A few days ago, Sir Clive Sinclair died. I owe him, or rather his most successful product, my career as a computer scientist. I bought myself a ZX Spectrum in my early teens, taught myself how to program it, and never looked back. The ArsTechnica obituary calls the Spectrum a “gaming computer”, and I guess that is mostly fair. Can’t say I ever used it for more than playing games or programming games.Continue reading “Thank You, Sir Clive Sinclair”
When I recently turned 50, a friend of mine gave me a book that was about as old as me – Timesharing System Design Concepts, by Richard W Watson. The copyright date is 1970, but the publishing date found online 1971. The book covers the hardware support and software techniques needed to provide multiple users with simultaneous access to a computer system. Typically, using remote teletype terminals. It is a wonderful book, reflecting on the state of computer technology around 1970. It shows both how many of the basic concepts we still use today were already in use back then, but at the same time just how far we have evolved computing since.Continue reading “Timesharing System Design Concepts (1970)”
I last blogged about my experience with thyroid cancer in early 2020. Back then, I said that I felt pretty much normal. That has indeed continued to be the case, and recently I was declared as having formally recovered from the cancer. The guideline is apparently that after two years with no sign of a cancer resurgence, you are considered fully recovered. Future follow-ups are the responsibility of the primary care system instead of the hospital, with something like yearly or bi-yearly follow-up tests. Not so much to look out for the cancer, but to keep the Levaxin prescription correct.Continue reading “Cancer Part 4: All’s Well that Ends Well”
The International Conference on Embedded Computer Systems: Architectures, Modeling and Simulation (SAMOS) XXI conference took place a couple of weeks ago. Like all other events in the past 18 months, it was virtual due to Covid-19. For more on the background on the SAMOS conference, see my blog post about SAMOS XIX (from 2019). This year, I presented a tutorial about our public release of the Simics simulator and took the chance to listen to most of the other conference talks.Continue reading “The SAMOS XXI Conference (Virtual)”
With Covid-19 still a bit of an issue, the summer of 2021 is yet another one for “svemester” (Sverige-semester, or Sweden-vacation). There are plenty of things to see, and one place that I finally got to visit was the old oil refinery at Oljeön in Ängelsberg, home to Engelsbergs oljefabrik and the world’s oldest preserved oil refinery dating back to the mid-1870s. It is a beautiful piece of industrial history, well-preserved and with good guided tours.Continue reading “Oljeön – The World’s Oldest Preserved Oil Refinery”
I recently stumbled on a blog post called Building Faster AMD64 Memset Routines, written by Joe Bialek of the Microsoft Security Response Center (MSRC). The blog describes his efforts to improve the performance of the Windows kernel memset() function, across all sizes of memory to set. The reported optimizations are quite fascinating, and could be summed by avoiding branches even at the cost of doing redundant stores. Basically, stores are free while branches are expensive.Continue reading “Microsoft Windows memset Optimization – Stores are Free”
Just like most people who can, I have been working from home since March 2020 due to Covid-19. Now that we are hopefully seeing the end of the pandemic in the west, it is worth looking back at the conference-from-home aspect of work-from-home. I have seen our Simics training, the Design Automation Conference (DAC), the Design and Verification Conference (DVCon) Europe, commercial training events, talks at industry conferences, guest lectures, and multiple internal Intel events go virtual. It has been interesting to see how this has worked out, and it seems to me that we are starting to see some good recurring patterns. People have adapted and figured out how to use video meeting technology better and better.Continue reading “About Virtual Events”
Wind River is celebrating their 40th anniversary as a company with a series of historical look-backs posted on the Wind River channel on YouTube. One of the videos is an interview with Jerry Fiddler who founded Wind River back in 1981, by Wind River current CEO Kevin Dallas. Jerry Fiddler talks about how he got started in computers, and especially about how Wind River got started and grew. It is both a fantastic set of historical anecdotes and some solid product management and strategy insights.Continue reading “Jerry Fiddler on the Early Days of Wind River and Building a Product”
DRAMsys is a simulator for modern RAM systems, built by researchers at Fraunhofer IESE and the Technische Universität Kaiserslautern. Over the past few years, I have heard several talks about the tool and also had the luck to talk a bit to the team behind it. It is an interesting piece of simulation technology, in particular for how it manages to build a truly cycle-accurate model on top of the approximately-timed (AT) style defined SystemC TLM-2.0.Continue reading “DRAMsys – Cycle-Accurate Simulation using Transactions”
Back when I was a PhD student working on worst-case execution-time (WCET) analysis, one of the leading groups researching the topic was the “Saarbrücken gang” led by Professor Reinhard Wilhelm. Last year, Professor Wilhelm published a retrospective look on their work on WCET in the Communications of the ACM. It is a really interesting history write-up from the perspective of the Saarbrücken group.Continue reading “Professor Reinhard Wilhelm on the History of WCET Analysis”