On Mon, 1 Feb 2021, Charan Teja Reddy wrote: > By defination, COMPACT[STALL|FAIL] events needs to be counted when there
s/defination/definition/ > is 'At least in one zone compaction wasn't deferred or skipped from the > direct compaction'. And when compaction is skipped or deferred, > COMPACT_SKIPPED will be returned but it will still go and update these > compaction events which is wrong in the sense that COMPACT[STALL|FAIL] > is counted without even trying the compaction. > > Correct this by skipping the counting of these events when > COMPACT_SKIPPED is returned for compaction. This indirectly also avoid > the unnecessary try into the get_page_from_freelist() when compaction is > not even tried. > > Signed-off-by: Charan Teja Reddy <chara...@codeaurora.org> > --- > mm/page_alloc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 519a60d..531f244 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4152,6 +4152,8 @@ __alloc_pages_direct_compact(gfp_t gfp_mask, unsigned > int order, > memalloc_noreclaim_restore(noreclaim_flag); > psi_memstall_leave(&pflags); > > + if (*compact_result == COMPACT_SKIPPED) > + return NULL; > /* > * At least in one zone compaction wasn't deferred or skipped, so let's > * count a compaction stall This makes sense, I wonder if it would also be useful to check that page == NULL, either in try_to_compact_pages() or here for COMPACT_SKIPPED?
