You gain *consistency*. Your TLB entries don't get messed up, your branch predictor doesn't get clobbered, you don't mysteriously lose 1.5M clocks every once in a while, etc.
Paul On Wed, Sep 2, 2026, 10:32 a.m. Edouard Klein <[email protected]> wrote: > My understanding of the benefits is that by removing interrupts and > context switching you gain a surprising amount of performance for > userspace tasks, each of which gets a basically dedicated core from > start to finish (with all its cache). Is that correct ? > > > Ron Minnich <[email protected]> writes: > > > from a book: > > > > "The NIX project targeted manycore architectures in which only a small > > subset of the cores could run kernel code. Consider N cores on a die > > arranged in a grid, with an on-die network providing a totally > > symmetric network and access to common memory. Let us assume that only > > of the cores can run a kernel and the rest can only run user mode > > code. NIX was intended to provide a kernel for such a system. The > > hypothetical target was a 1,024 core system, as several vendors hinted > > that was reasonable in the 2016 time frame. We picked this number as > > it was large enough to far exceed any possible number of user > > processes: the Plan 9 systems on which NIX was based use only a small > > fraction of this number. Further, the realities of memory bandwidth > > will limit the number of active cores to small single digits. We also > > wanted to have a system with good support for Go, the then-new > > language from Google. At the time, Go was a statically linked language > > and a typical binary was about 1 MiB. This influenced the design of > > the virtual memory system in NIX. The base page size was expanded from > > 4,096 bytes to 2 MiB. We further extended Plan 9’s virtual memory > > model to transparently support GiB pages, but via a simple heuristic > > that made it far less complex than existing systems. The target system > > had a 32:1 ratio of application cores to kernel cores (a close match > > to the Blue Gene/Q system at 16:1), and it was designed for space > > sharing, not time sharing, and had a minimum page size of 2 MiB; > > supported GiB pages; and yet, at the same time, looked in all other > > ways like a standard Plan 9 system." > > > > > > note that the Esperanto system, released in 2017 or so, closely > > matches this model, as do other risc-v systems. I have a few of these > > cards, so may take a look at whether it might work. > > > > On Tue, Sep 1, 2026 at 1:38 PM <[email protected]> wrote: > >> > >> For context, what was NIX? How did it differ from Plan 9 4th edition? > What were the goals? > >> 9fans / 9fans / see discussions + participants + delivery options > Permalink ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/Ta20bdef5171bc207-Mcfd0373e764911ef1a1ee294 Delivery options: https://9fans.topicbox.com/groups/9fans/subscription
