Re: [PATCH v5 4/4] mm: Introduce per-thpsize swapin control policy

From: Matthew Wilcox
Date: Sun Jul 28 2024 - 23:52:53 EST


On Fri, Jul 26, 2024 at 09:46:18PM +1200, Barry Song wrote:
> A user space interface can be implemented to select different swap-in
> order policies, similar to the mTHP allocation order policy. We need
> a distinct policy because the performance characteristics of memory
> allocation differ significantly from those of swap-in. For example,
> SSD read speeds can be much slower than memory allocation. With
> policy selection, I believe we can implement mTHP swap-in for
> non-SWAP_SYNCHRONOUS scenarios as well. However, users need to understand
> the implications of their choices. I think that it's better to start
> with at least always never. I believe that we will add auto in the
> future to tune automatically, which can be used as default finally.

I strongly disagree. Use the same sysctl as the other anonymous memory
allocations.