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Comment by ohdeargodno | Hacker News Reader

Dozens of years of kernel building, dozens of OSes, dozens of physical architectures, all having settled on minimum 4KB pages being a right balance between performance and memory usage, wiped away by a single offhand comment with no knowledge about the situation. Now that's HN.

Just the sheer TLB memory usage and performance implication of doing single byte pages would send CPU performance back to the stone age.

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Completely false. The 4 KiB page size came from a machine with a total of 512 KiB (1962 Atlas, 3072B pages, 96k 48b words). It hasn’t scaled at all for inertia reasons and it has real and measurable costs. 64 KiB would have been the better choice IMO, but 16 is better than 4.

Hence the "minimum" part. The thread is literally about Android being compiled for 16KB pages, CPU support for larger pages has grown, easily up to 4MB for most consumer CPUs.

Going down _lower_ than 4KB is purely a waste of memory and performance.

My proposed design has many page sizes - nothing stops a software developer making all mappings multiples of 4kb and not using the byte sized pages.

My example was 1mb, 4kb and 1 byte pages - but a real design would probably use every power of two, or every even power of two to get best use of the TLB space.

It hasn't been done before because of a chicken and egg problem. CPU designers don't build it because no OS has the ability to use it, and no OS uses it because no CPU supports it. It would be a substantial amount of work for both parties.

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