Reply to post: Re: 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

Re: Time for NUMA, Embrace your Inner CSP

It's fascinating how normal UNIX commands would be a good fit for CSP architectures.

Very nearly! However piping UNIX commands together is closer to Actor Model than CSP; the pipes really are asynchronous IPC pipes, not synchronous channels that CSP has. Also there's some limits on how commands can be plumbed together; I don't think you can do anything circular.

The irony of IPC pipes is that what they provide is an asynchronous byte transport, but they're implemented in the kernel using memory shared between cores and semaphores. The ironic part is that that shared memory is faked; it's an SMP construct that is synthesised on top of a NUMA architecture. That in turn is knitted together by high speed serial links (QPI, Hypertransport), and these links are asynchronous byte transports! Grrrrr!

The one hope is that microkernel OSes come to predominate, with bits of the OS joined up using IPC pipes instead of shared memory. That opens up the opportunity for the hardware designers to think more seriously about dropping SMP. It may happen; even Linux, courtesy of Google's Project Treble, is beginning to head that way.

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