On Thu, 23 Jan 2025 11:11:13 -0600 Vinay Banakar <vny@xxxxxxxxxx> wrote: > On Wed, Jan 22, 2025 at 2:05 PM SeongJae Park <sj@xxxxxxxxxx> wrote: > > damon_pa_pageout() from mm/damon/paddr.c also calls shrink_folio_list() similar > > to madvise.c, but it doesn't aware such batching behavior. Have you checked > > that path? > > Thanks for catching this path. In damon_pa_pageout(), > shrink_folio_list() processes all pages from a single NUMA node that > were collected (filtered) from a single DAMON region (r->ar.start to > r->ar.end). This means it could be processing anywhere from 1 page up > to ULONG_MAX pages from a single node at once. Thank you Vinay. That's same to my understanding, except that it is not limited to a single NUMA node. A region can have any start and end physical addresses, so it could cover memory of different NUMA nodes. > With the patch, we'll > send a single IPI for TLB flush for the entire region, reducing IPIs > by a factor equal to the number of pages being reclaimed by DAMON at > once (decided by damon_reclaim_quota). I guess the fact that the pages could belong to differnt NUMA nodes doesn't make difference here? > > My only concern here would be the overhead of maintaining the > temporary pageout_list for batching. However, during BIO submission, > the patch checks if the folio was reactivated, so submitting to BIO in > bulk should be safe. > > Another option would be to modify shrink_folio_list() to force batch > flushes for up to N pages (512) at a time, rather than relying on > callers to do the batching via folio_list. Both sounds good to me :) Thanks, SJ > > Thanks! > Vinay
