From 1d1b4c6cabd611699fd75d58a6331950b8de6500 Mon Sep 17 00:00:00 2001 From: Yang Shi Date: Tue, 22 Oct 2019 04:54:20 +0800 Subject: [PATCH] mm: thp: move deferred split queue to memcg's nodeinfo The commit 87eaceb3faa59b9b4d940ec9554ce251325d83fe ("mm: thp: make deferred split shrinker memcg aware") makes deferred split queue per memcg to resolve memcg pre-mature OOM problem. But, all nodes end up sharing the same queue instead of one queue per-node before the commit. It is not a big deal for memcg limit reclaim, but it may cause global kswapd shrink THPs from a different node. And, 0-day testing reported -19.6% regression of stress-ng's madvise test [1]. I didn't see that much regression on my test box (24 threads, 48GB memory, 2 nodes), with the same test (stress-ng --timeout 1 --metrics-brief --sequential 72 --class vm --exclude spawn,exec), I saw average -3% (run the same test 10 times then calculate the average since the test itself may have most 15% variation according to my test) regression sometimes (not every time, sometimes I didn't see regression at all). This might be caused by deferred split queue lock contention. With some configuration (i.e. just one root memcg) the lock contention my be worse than before (given 2 nodes, two locks are reduced to one lock). So, moving deferred split queue to memcg's nodeinfo to make it NUMA aware again. With this change stress-ng's madvise test shows average 4% improvement sometimes and I didn't see degradation anymore. [1]: https://lore.kernel.org/lkml/20190930084604.GC17687@shao2-debian/ Cc: Kirill A. Shutemov Cc: Kirill Tkhai Cc: Johannes Weiner Cc: Michal Hocko Cc: Hugh Dickins Cc: Shakeel Butt Cc: David Rientjes Signed-off-by: Yang Shi Reviewed-by: Xunlei Pang --- include/linux/memcontrol.h | 4 ++++ mm/huge_memory.c | 15 +++++++++------ mm/memcontrol.c | 29 +++++++++++++++++------------ 3 files changed, 30 insertions(+), 18 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 992e9139497f..5e62ed3bbb71 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -145,6 +145,10 @@ struct mem_cgroup_per_node { bool dirty; /* mecg has too many dirty pages */ bool writeback; /* memcg has too many writeback */ +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + struct deferred_split deferred_split_queue; +#endif + struct mem_cgroup *memcg; /* Back pointer, we cannot */ /* use container_of */ }; diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f5f0de66e49c..e5269e7d0d40 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -486,10 +486,11 @@ pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) static inline struct deferred_split *get_deferred_split_queue(struct page *page) { struct mem_cgroup *memcg = compound_head(page)->mem_cgroup; - struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); + int nid = page_to_nid(page); + struct pglist_data *pgdat = NODE_DATA(nid); if (memcg) - return &memcg->deferred_split_queue; + return &memcg->nodeinfo[nid]->deferred_split_queue; else return &pgdat->deferred_split_queue; } @@ -2840,12 +2841,13 @@ void deferred_split_huge_page(struct page *page) static unsigned long deferred_split_count(struct shrinker *shrink, struct shrink_control *sc) { - struct pglist_data *pgdata = NODE_DATA(sc->nid); + int nid = sc->nid; + struct pglist_data *pgdata = NODE_DATA(nid); struct deferred_split *ds_queue = &pgdata->deferred_split_queue; #ifdef CONFIG_MEMCG if (sc->memcg) - ds_queue = &sc->memcg->deferred_split_queue; + ds_queue = &sc->memcg->nodeinfo[nid]->deferred_split_queue; #endif return READ_ONCE(ds_queue->split_queue_len); } @@ -2853,7 +2855,8 @@ static unsigned long deferred_split_count(struct shrinker *shrink, static unsigned long deferred_split_scan(struct shrinker *shrink, struct shrink_control *sc) { - struct pglist_data *pgdata = NODE_DATA(sc->nid); + int nid = sc->nid; + struct pglist_data *pgdata = NODE_DATA(nid); struct deferred_split *ds_queue = &pgdata->deferred_split_queue; unsigned long flags; LIST_HEAD(list), *pos, *next; @@ -2862,7 +2865,7 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, #ifdef CONFIG_MEMCG if (sc->memcg) - ds_queue = &sc->memcg->deferred_split_queue; + ds_queue = &sc->memcg->nodeinfo[nid]->deferred_split_queue; #endif spin_lock_irqsave(&ds_queue->split_queue_lock, flags); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 4c52f6c7146e..9b9e6b5e4aec 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5006,6 +5006,12 @@ static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node) pn->on_tree = false; pn->memcg = memcg; +#ifdef CONFIG_TRANSPARENT_HUGEPAGE + spin_lock_init(&pn->deferred_split_queue.split_queue_lock); + INIT_LIST_HEAD(&pn->deferred_split_queue.split_queue); + pn->deferred_split_queue.split_queue_len = 0; +#endif + memcg->nodeinfo[node] = pn; return 0; } @@ -5084,11 +5090,6 @@ static struct mem_cgroup *mem_cgroup_alloc(void) INIT_LIST_HEAD(&memcg->cgwb_list); #endif kidled_memcg_init(memcg); -#ifdef CONFIG_TRANSPARENT_HUGEPAGE - spin_lock_init(&memcg->deferred_split_queue.split_queue_lock); - INIT_LIST_HEAD(&memcg->deferred_split_queue.split_queue); - memcg->deferred_split_queue.split_queue_len = 0; -#endif idr_replace(&mem_cgroup_idr, memcg, memcg->id.id); return memcg; fail: @@ -5425,6 +5426,8 @@ static int mem_cgroup_move_account(struct page *page, unsigned int nr_pages = compound ? hpage_nr_pages(page) : 1; int ret; bool anon; + struct deferred_split *ds_queue; + int nid = page_to_nid(page); VM_BUG_ON(from == to); VM_BUG_ON_PAGE(PageLRU(page), page); @@ -5472,10 +5475,11 @@ static int mem_cgroup_move_account(struct page *page, #ifdef CONFIG_TRANSPARENT_HUGEPAGE if (compound && !list_empty(page_deferred_list(page))) { - spin_lock(&from->deferred_split_queue.split_queue_lock); + ds_queue = &from->nodeinfo[nid]->deferred_split_queue; + spin_lock(&ds_queue->split_queue_lock); list_del_init(page_deferred_list(page)); - from->deferred_split_queue.split_queue_len--; - spin_unlock(&from->deferred_split_queue.split_queue_lock); + ds_queue->split_queue_len--; + spin_unlock(&ds_queue->split_queue_lock); } #endif /* @@ -5489,11 +5493,12 @@ static int mem_cgroup_move_account(struct page *page, #ifdef CONFIG_TRANSPARENT_HUGEPAGE if (compound && list_empty(page_deferred_list(page))) { - spin_lock(&to->deferred_split_queue.split_queue_lock); + ds_queue = &to->nodeinfo[nid]->deferred_split_queue; + spin_lock(&ds_queue->split_queue_lock); list_add_tail(page_deferred_list(page), - &to->deferred_split_queue.split_queue); - to->deferred_split_queue.split_queue_len++; - spin_unlock(&to->deferred_split_queue.split_queue_lock); + &ds_queue->split_queue); + ds_queue->split_queue_len++; + spin_unlock(&ds_queue->split_queue_lock); } #endif -- GitLab