Reply to post: Time for NUMA, Embrace your Inner CSP

Hate to ruin your day, but... Boffins cook up fresh Meltdown, Spectre CPU design flaw exploits

bazza Silver badge

Time for NUMA, Embrace your Inner CSP

This particular round of hardware flaws has come about because the chip manufacturers have continued to support SMP whilst building architectures that are, effectively, NUMA. The SMP is synthesised on top of the underlying NUMA architecture. That's what all these cache coherency and memory access protocols are for.

This is basically a decades long bodge to save us all having to rewrite OSes and a whole shed load of software. This is the biggest hint that the entire computing community has been recklessly lazy by failing to change. If we want speed and security it seems that we will have to rewrite a lot of stuff so that it works on pure NUMA architectures.

<smugmode>The vast majority of code I've ever written is either Actor Model or Communicating Sequential Processes, so I'm already there</smugmode>

Seriously though, languages like Rust do CSP as part of their native language. An OS written in Rust using its CSPness wouldn't need SMP. Though the current compiler would need changing because of course it too currently assumes an underlying SMP hardware architecture... If the SMP bit of our lives can be ditched we'll have faster CPUs and no cache coherency based design flaws, instead of slowed down software running on top of bodged and rebodged CPU microcode.

Besides, CSP is great once you get your head around it. It's far easier to write correct and very reliable multi-threaded software using CSP than using shared memory and mutexes. You can do a mathematical proof of correctness with a CSP system, whereas you cannot even exhaustively test a multithreaded, shared memory + mutexes system.

Oh, and Inmos / Tony Hoare got it right, and everyone else has been lazy and wrong.

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