> > > Are you suggesting that the problem is that should_reclaim_retry is > > > iterating nodes which are not allowed by cpusets and that makes the > > > retry loop happening more than unnecessary? > > > > Yes, exactly. > > > > > > > > Is there any reason why you haven't done the same that the page > > > allocator does in this case? > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > > index 28f80daf5c04..cbf09c0e3b8a 100644 > > > --- a/mm/page_alloc.c > > > +++ b/mm/page_alloc.c > > > @@ -4098,6 +4098,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order, > > > unsigned long min_wmark = min_wmark_pages(zone); > > > bool wmark; > > > > > > + if (cpusets_enabled() && > > > + (alloc_flags & ALLOC_CPUSET) && > > > + !__cpuset_zone_allowed(zone, gfp_mask)) > > > + continue; > > > + > > > available = reclaimable = zone_reclaimable_pages(zone); > > > available += zone_page_state_snapshot(zone, NR_FREE_PAGES); > > > > > > > That was my original version, but I found that the problem exists in > > other places. > > Please see the function flow below. > > > > __alloc_pages_slowpath: > > > > get_page_from_freelist > > __cpuset_zone_allowed /* check the node */ > > > > __alloc_pages_direct_reclaim > > shrink_zones > > cpuset_zone_allowed（）/* check the node */ > > > > __alloc_pages_direct_compact > > try_to_compact_pages > > /* do not check the cpuset_zone_allowed（）*/ > > > > should_reclaim_retry > > /* do not check the cpuset_zone_allowed（）*/ > > > > should_compact_retry > > compaction_zonelist_suitable > > /* do not check the cpuset_zone_allowed（）*/ > > > > Should we add __cpuset_zone_allowed() checks in the three functions > > listed above, > > or should we set the nodemask in __alloc_pages_slowpath() if it is empty > > and the request comes from user space? > > cpuset integration into the page allocator is rather complex (check > ALLOC_CPUSET) use. Reviewing your change is not an easy task to make > sure all the subtlety is preserved. Therefore I would suggest addressing > the specific issue you have found. > Got it，thanks for your suggestion， i will send the next version soon. > -- > Michal Hocko > SUSE Labs
