On Thu, Apr 14, 2022 at 03:48:33PM +1000, Alistair Popple wrote: > Peter Xu <peterx@xxxxxxxxxx> writes: > > > The stub for non_swap_entry() may not help much, because MAX_SWAPFILES has > > already contained all the information to decide whether a swap entry is > > real swap entry of pesudo ones (migrations, ...). > > > > There can be some performance influences on non_swap_entry() with below > > conditions all met: > > > > !CONFIG_MIGRATION && !CONFIG_MEMORY_FAILURE && !CONFIG_DEVICE_PRIVATE > > > > But that's definitely not the major config most machines will use, at the > > meantime it's already in a slow path of swap entry (being parsed from a > > swap pte), so IMHO it shouldn't be a major issue. Also according to the > > analysis from Alistair, somehow the stub didn't do the job right [1]. > > I wasn't so much concerned about execution speed given it's on the slow path > anyway but overall code size, which is one reason all those config options might > be disabled. However in practice it made little to no difference as those config > options already remove most of the extra code so I agree we can drop the stub. I see, yeah that's a good point. I'd wildly guess a minumum set of Linux build could still like that, but not strongly, as I'd first think about not having CONFIG_SWAP at all if so. > > Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx> Thanks! -- Peter Xu
