On 02.08.20 14:54, Charan Teja Reddy wrote: > When onlining a first memory block in a zone, pcp lists are not updated > thus pcp struct will have the default setting of ->high = 0,->batch = 1. > This means till the second memory block in a zone(if it have) is onlined > the pcp lists of this zone will not contain any pages because pcp's > ->count is always greater than ->high thus free_pcppages_bulk() is > called to free batch size(=1) pages every time system wants to add a > page to the pcp list through free_unref_page(). To put this in a word, > system is not using benefits offered by the pcp lists when there is a > single onlineable memory block in a zone. Correct this by always > updating the pcp lists when memory block is onlined.
I guess such setups are rare ... but I can imagine it being the case with virtio-mem in the future ... not 100% if this performance optimization is really relevant in practice ... how did you identify this? > > Signed-off-by: Charan Teja Reddy <chara...@codeaurora.org> > --- > mm/memory_hotplug.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index dcdf327..7f62d69 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -854,8 +854,7 @@ int __ref online_pages(unsigned long pfn, unsigned long > nr_pages, > node_states_set_node(nid, &arg); > if (need_zonelists_rebuild) > build_all_zonelists(NULL); > - else > - zone_pcp_update(zone); > + zone_pcp_update(zone); > > init_per_zone_wmark_min(); > > Does, in general, look sane to me. Reviewed-by: David Hildenbrand <da...@redhat.com> -- Thanks, David / dhildenb
