Last year, I did a Simics webinar which included a two-part demo of how to use Simics to debug an endianness bug in a networked system as it migrates from big-endian to a little-endian system. Along the way, I also showed off various Simics features like reverse execution and checkpointing and scripted execution.
The demo is now online at the Wind River Youtube channel, and the setup is explained in a blog post at the Wind River company blog which is worth reading before watching the video.
On the Wind River corporate blog, I have put up a blog post about how Wind River Education Services is going to use Simics to teach networking. What is interesting with this approach is that it shows how a virtual platform can be used for tasks like teaching that don’t have much to do with hardware modeling or similar “typical” VP uses. In this case, the key value is encapsulation of a set of machines running real operating systems and software stacks, and with lots of networks connecting them.
Once upon a time, all programming was bare metal programming. You coded to the processor core, you took care of memory, and no operating system got in your way. Over time, as computer programmers, users, and designers got more sophisticated and as more clock cycles and memory bytes became available, more and more layers were added between the programmer and the computer. However, I have recently spotted what might seem like a trend away from ever-thicker software stacks, in the interest of performance and, in particular, latency.
After a long break, this is another blog post in the series of “how to do modeling for virtual platforms”. The previous installments dealt with checkpointing and determinism.
This post is about the use of indirection in a model to increase its flexibility and ease of use, at the cost of a bit more work for the first model to be created.In particular, indirection in the sense of having explicit objects in a simulation to represent things like networks and cables connecting virtual machines.
Yes, when does hardware acceleration make sense in networking? Hardware acceleration in the common sense of “TCP offload”. This question was answered by a very nicely reasoned “no” in an article by Mike Odell in ACM Queue called “Network Front-End Processors, Yet Again“.