He said big vectors. You're talking about sub-page fragmentation.
Big vectors inherently avoid sub-page fragmentation because they're allocated directly via mmap. The only thing that matters is having unreserved address space, and 64bit gives you a lot.
What you say is true for a worst case load of millions of vectors that are larger than half of the mmap threshold size (typically roughly page size or a small multiple of it). So this might just be a semantic disagreement, but I don't think of millions of 3KB vectors as 'big' vs a smaller number of MB or GB vectors.
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It's the physical memory that fragments, not the virtual address space. So it's about the amount of physical memory available, not address sizes.
He said big vectors. You're talking about sub-page fragmentation.
Big vectors inherently avoid sub-page fragmentation because they're allocated directly via mmap. The only thing that matters is having unreserved address space, and 64bit gives you a lot.
What you say is true for a worst case load of millions of vectors that are larger than half of the mmap threshold size (typically roughly page size or a small multiple of it). So this might just be a semantic disagreement, but I don't think of millions of 3KB vectors as 'big' vs a smaller number of MB or GB vectors.