On Mon, Jul 29, 2024 at 3:52 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: > > 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. In versions v1-v4, we used the same controls as anonymous memory allocations. Ying expressed concerns that this approach isn't always ideal, especially for non-zRAM devices, as SSD read speeds can be much slower than memory allocation. I think his concern is reasonable to some extent. However, this patchset only addresses scenarios involving zRAM-like devices and will not impact SSDs. I would like to get Ying's feedback on whether it's acceptable to drop this one in v6. Thanks Barry
