Comment by monocasa
10 hours ago
To be fair, IBM did this in the 90s with the PowerPC 615, which had PowerPC and x86 decoders on the same core.
10 hours ago
To be fair, IBM did this in the 90s with the PowerPC 615, which had PowerPC and x86 decoders on the same core.
But those ARM and s390x decoders have a “Telum III” architecture behind them with a cache that’s pretty innovative.
IBM has never stopped innovating. It’s just that most people can’t afford their machines.
Yeah, their cache work is undeniably really cool.
That being said I think it's a natural consequence of the difference between a mainframe and commodity servers. A mainframe is going to be running pretty disparate workloads simultaneously, so it makes sense to steal from your neighbor if they aren't using their cache. Whereas it's more likely that a commodity server is just running the same server on each core, and if you have a different workload, you pick a different shape of server to run it on. There are pros and cons to both.
I do wonder about the spectre consequences of borrowing cache lines from other cores though.
Even though their CPUs are insanely fast, the real power of mainframes is in their IO. The amount of data you can push through those machines is absolutely mind blowing.
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What's unique about their cache ?
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