On 2024/11/18 12:21, Matthew Wilcox wrote: > On Mon, Nov 18, 2024 at 05:14:14PM +1300, Barry Song wrote: >> On Mon, Nov 18, 2024 at 5:03 PM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: >>> >>> On Sat, Nov 16, 2024 at 09:16:58AM +0000, Chen Ridong wrote: >>>> 2. In shrink_page_list function, if folioN is THP(2M), it may be splited >>>> and added to swap cache folio by folio. After adding to swap cache, >>>> it will submit io to writeback folio to swap, which is asynchronous. >>>> When shrink_page_list is finished, the isolated folios list will be >>>> moved back to the head of inactive lru. The inactive lru may just look >>>> like this, with 512 filioes have been move to the head of inactive lru. >>> >>> I was hoping that we'd be able to stop splitting the folio when adding >>> to the swap cache. Ideally. we'd add the whole 2MB and write it back >>> as a single unit. >> >> This is already the case: adding to the swapcache doesn’t require splitting >> THPs, but failing to allocate 2MB of contiguous swap slots will. > > Agreed we need to understand why this is happening. As I've said a few > times now, we need to stop requiring contiguity. Real filesystems don't > need the contiguity (they become less efficient, but they can scatter a > single 2MB folio to multiple places). > > Maybe Chris has a solution to this in the works? > Hi, Chris, do you have a better idea to solve this issue? Best regards, Ridong
