On Mon 07-07-14 14:55:58, Johannes Weiner wrote: > Pages are now uncharged at release time, and all sources of batched > uncharges operate on lists of pages. Directly use those lists, and > get rid of the per-task batching state. > > This also batches statistics accounting, in addition to the res > counter charges, to reduce IRQ-disabling and re-enabling. It is probably worth noticing that there is a higher chance of missing threshold events now when we can accumulate huge number of uncharges during munmaps. I do not think this is earth shattering and the overall improvement is worth it but changelog should mention it. > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> With the follow up fix from http://marc.info/?l=linux-mm&m=140552814228135&w=2 Acked-by: Michal Hocko <mhocko@xxxxxxx> one nit below. [...] > +static void uncharge_list(struct list_head *page_list) > +{ > + struct mem_cgroup *memcg = NULL; > + unsigned long nr_memsw = 0; > + unsigned long nr_anon = 0; > + unsigned long nr_file = 0; > + unsigned long nr_huge = 0; > + unsigned long pgpgout = 0; > + unsigned long nr_mem = 0; > + struct list_head *next; > + struct page *page; > + > + next = page_list->next; > + do { I would use list_for_each_entry here which would also save list_empty check in mem_cgroup_uncharge_list > + unsigned int nr_pages = 1; > + struct page_cgroup *pc; > + > + page = list_entry(next, struct page, lru); > + next = page->lru.next; > + > + VM_BUG_ON_PAGE(PageLRU(page), page); > + VM_BUG_ON_PAGE(page_count(page), page); > + > + pc = lookup_page_cgroup(page); > + if (!PageCgroupUsed(pc)) > + continue; > + > + /* > + * Nobody should be changing or seriously looking at > + * pc->mem_cgroup and pc->flags at this point, we have > + * fully exclusive access to the page. > + */ > + > + if (memcg != pc->mem_cgroup) { > + if (memcg) { > + uncharge_batch(memcg, pgpgout, nr_mem, nr_memsw, > + nr_anon, nr_file, nr_huge, page); > + pgpgout = nr_mem = nr_memsw = 0; > + nr_anon = nr_file = nr_huge = 0; > + } > + memcg = pc->mem_cgroup; > + } > + > + if (PageTransHuge(page)) { > + nr_pages <<= compound_order(page); > + VM_BUG_ON_PAGE(!PageTransHuge(page), page); > + nr_huge += nr_pages; > + } > + > + if (PageAnon(page)) > + nr_anon += nr_pages; > + else > + nr_file += nr_pages; > + > + if (pc->flags & PCG_MEM) > + nr_mem += nr_pages; > + if (pc->flags & PCG_MEMSW) > + nr_memsw += nr_pages; > + pc->flags = 0; > + > + pgpgout++; > + } while (next != page_list); > + > + if (memcg) > + uncharge_batch(memcg, pgpgout, nr_mem, nr_memsw, > + nr_anon, nr_file, nr_huge, page); > +} -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>