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> ZFS is not tied to the memory allocator in Solaris, I’m very unclear how you could have made that mistake

> And yes, the 1G per TB is for the in memory block map, which is a requirement for deduplucation on the default block size.

You actually answered your own question: it's antiquated because of the assumption it is possible to get contiguous RAM for that mapping. On modern Linux, that is only possible if you reserve it pre-boot.

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> it's antiquated because of the assumption it is possible to get contiguous RAM for that mapping.

source on that? (and even if that's the case, wouldn't that be an implementation detail? E.g. implementations can spill it to L2ARC, but somehow not to different memory locations?)

My memory is that this mapping does have to be contiguous, but I'll dig it up in the code and link it here either way.

still planning on linking that code?

The Solaris memory allocator is not contiguous either though

This is a whole rabbit hole... but essentially, Linux uses a naive buddy allocator for physical RAM, and Solaris was more interesting.

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