On Wed, Apr 07, 2021 at 10:27:12PM +0100, Matthew Wilcox wrote: > Doing I/O without any lock held already works; it just uses the file > refcount. It would be better to use a vma refcount, as I already said.
The original workload that I developed SPF for (waaaay back when) was prefaulting a single huge vma. Using a vma refcount was a total loss because it resulted in the same cacheline contention that down_read() was having. As such, I'm always incredibly sad to see mention of vma refcounts. They're fundamentally not solving the problem :/
