From e4dde56cd208674ce899b47589f263499e5b8cdc Mon Sep 17 00:00:00 2001 From: Yu Zhao Date: Wed, 21 Dec 2022 21:19:04 -0700 Subject: mm: multi-gen LRU: per-node lru_gen_folio lists For each node, memcgs are divided into two generations: the old and the young. For each generation, memcgs are randomly sharded into multiple bins to improve scalability. For each bin, an RCU hlist_nulls is virtually divided into three segments: the head, the tail and the default. An onlining memcg is added to the tail of a random bin in the old generation. The eviction starts at the head of a random bin in the old generation. The per-node memcg generation counter, whose reminder (mod 2) indexes the old generation, is incremented when all its bins become empty. There are four operations: 1. MEMCG_LRU_HEAD, which moves an memcg to the head of a random bin in its current generation (old or young) and updates its "seg" to "head"; 2. MEMCG_LRU_TAIL, which moves an memcg to the tail of a random bin in its current generation (old or young) and updates its "seg" to "tail"; 3. MEMCG_LRU_OLD, which moves an memcg to the head of a random bin in the old generation, updates its "gen" to "old" and resets its "seg" to "default"; 4. MEMCG_LRU_YOUNG, which moves an memcg to the tail of a random bin in the young generation, updates its "gen" to "young" and resets its "seg" to "default". The events that trigger the above operations are: 1. Exceeding the soft limit, which triggers MEMCG_LRU_HEAD; 2. The first attempt to reclaim an memcg below low, which triggers MEMCG_LRU_TAIL; 3. The first attempt to reclaim an memcg below reclaimable size threshold, which triggers MEMCG_LRU_TAIL; 4. The second attempt to reclaim an memcg below reclaimable size threshold, which triggers MEMCG_LRU_YOUNG; 5. Attempting to reclaim an memcg below min, which triggers MEMCG_LRU_YOUNG; 6. Finishing the aging on the eviction path, which triggers MEMCG_LRU_YOUNG; 7. Offlining an memcg, which triggers MEMCG_LRU_OLD. Note that memcg LRU only applies to global reclaim, and the round-robin incrementing of their max_seq counters ensures the eventual fairness to all eligible memcgs. For memcg reclaim, it still relies on mem_cgroup_iter(). Link: https://lkml.kernel.org/r/20221222041905.2431096-7-yuzhao@google.com Signed-off-by: Yu Zhao Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Michael Larabel Cc: Michal Hocko Cc: Mike Rapoport Cc: Roman Gushchin Cc: Suren Baghdasaryan Signed-off-by: Andrew Morton --- mm/vmscan.c | 374 ++++++++++++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 341 insertions(+), 33 deletions(-) (limited to 'mm/vmscan.c') diff --git a/mm/vmscan.c b/mm/vmscan.c index 5a167f8efc38..178465a503db 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -55,6 +55,8 @@ #include #include #include +#include +#include #include #include @@ -135,11 +137,6 @@ struct scan_control { /* Always discard instead of demoting to lower tier memory */ unsigned int no_demotion:1; -#ifdef CONFIG_LRU_GEN - /* help kswapd make better choices among multiple memcgs */ - unsigned long last_reclaimed; -#endif - /* Allocation order */ s8 order; @@ -3185,6 +3182,9 @@ DEFINE_STATIC_KEY_ARRAY_FALSE(lru_gen_caps, NR_LRU_GEN_CAPS); for ((type) = 0; (type) < ANON_AND_FILE; (type)++) \ for ((zone) = 0; (zone) < MAX_NR_ZONES; (zone)++) +#define get_memcg_gen(seq) ((seq) % MEMCG_NR_GENS) +#define get_memcg_bin(bin) ((bin) % MEMCG_NR_BINS) + static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid) { struct pglist_data *pgdat = NODE_DATA(nid); @@ -4453,8 +4453,7 @@ done: if (sc->priority <= DEF_PRIORITY - 2) wait_event_killable(lruvec->mm_state.wait, max_seq < READ_ONCE(lrugen->max_seq)); - - return max_seq < READ_ONCE(lrugen->max_seq); + return false; } VM_WARN_ON_ONCE(max_seq != READ_ONCE(lrugen->max_seq)); @@ -4527,8 +4526,6 @@ static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) VM_WARN_ON_ONCE(!current_is_kswapd()); - sc->last_reclaimed = sc->nr_reclaimed; - /* check the order to exclude compaction-induced reclaim */ if (!min_ttl || sc->order || sc->priority == DEF_PRIORITY) return; @@ -5117,8 +5114,7 @@ static bool should_run_aging(struct lruvec *lruvec, unsigned long max_seq, * 1. Defer try_to_inc_max_seq() to workqueues to reduce latency for memcg * reclaim. */ -static unsigned long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, - bool can_swap) +static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool can_swap) { unsigned long nr_to_scan; struct mem_cgroup *memcg = lruvec_memcg(lruvec); @@ -5136,10 +5132,8 @@ static unsigned long get_nr_to_scan(struct lruvec *lruvec, struct scan_control * if (sc->priority == DEF_PRIORITY) return nr_to_scan; - try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, false); - /* skip this lruvec as it's low on cold folios */ - return 0; + return try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, false) ? -1 : 0; } static unsigned long get_nr_to_reclaim(struct scan_control *sc) @@ -5148,29 +5142,18 @@ static unsigned long get_nr_to_reclaim(struct scan_control *sc) if (!global_reclaim(sc)) return -1; - /* discount the previous progress for kswapd */ - if (current_is_kswapd()) - return sc->nr_to_reclaim + sc->last_reclaimed; - return max(sc->nr_to_reclaim, compact_gap(sc->order)); } -static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +static bool try_to_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) { - struct blk_plug plug; + long nr_to_scan; unsigned long scanned = 0; unsigned long nr_to_reclaim = get_nr_to_reclaim(sc); - lru_add_drain(); - - blk_start_plug(&plug); - - set_mm_walk(lruvec_pgdat(lruvec)); - while (true) { int delta; int swappiness; - unsigned long nr_to_scan; if (sc->may_swap) swappiness = get_swappiness(lruvec, sc); @@ -5180,7 +5163,7 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc swappiness = 0; nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness); - if (!nr_to_scan) + if (nr_to_scan <= 0) break; delta = evict_folios(lruvec, sc, swappiness); @@ -5197,11 +5180,252 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc cond_resched(); } + /* whether try_to_inc_max_seq() was successful */ + return nr_to_scan < 0; +} + +static int shrink_one(struct lruvec *lruvec, struct scan_control *sc) +{ + bool success; + unsigned long scanned = sc->nr_scanned; + unsigned long reclaimed = sc->nr_reclaimed; + int seg = lru_gen_memcg_seg(lruvec); + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + /* see the comment on MEMCG_NR_GENS */ + if (!lruvec_is_sizable(lruvec, sc)) + return seg != MEMCG_LRU_TAIL ? MEMCG_LRU_TAIL : MEMCG_LRU_YOUNG; + + mem_cgroup_calculate_protection(NULL, memcg); + + if (mem_cgroup_below_min(NULL, memcg)) + return MEMCG_LRU_YOUNG; + + if (mem_cgroup_below_low(NULL, memcg)) { + /* see the comment on MEMCG_NR_GENS */ + if (seg != MEMCG_LRU_TAIL) + return MEMCG_LRU_TAIL; + + memcg_memory_event(memcg, MEMCG_LOW); + } + + success = try_to_shrink_lruvec(lruvec, sc); + + shrink_slab(sc->gfp_mask, pgdat->node_id, memcg, sc->priority); + + if (!sc->proactive) + vmpressure(sc->gfp_mask, memcg, false, sc->nr_scanned - scanned, + sc->nr_reclaimed - reclaimed); + + sc->nr_reclaimed += current->reclaim_state->reclaimed_slab; + current->reclaim_state->reclaimed_slab = 0; + + return success ? MEMCG_LRU_YOUNG : 0; +} + +#ifdef CONFIG_MEMCG + +static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc) +{ + int gen; + int bin; + int first_bin; + struct lruvec *lruvec; + struct lru_gen_folio *lrugen; + const struct hlist_nulls_node *pos; + int op = 0; + struct mem_cgroup *memcg = NULL; + unsigned long nr_to_reclaim = get_nr_to_reclaim(sc); + + bin = first_bin = get_random_u32_below(MEMCG_NR_BINS); +restart: + gen = get_memcg_gen(READ_ONCE(pgdat->memcg_lru.seq)); + + rcu_read_lock(); + + hlist_nulls_for_each_entry_rcu(lrugen, pos, &pgdat->memcg_lru.fifo[gen][bin], list) { + if (op) + lru_gen_rotate_memcg(lruvec, op); + + mem_cgroup_put(memcg); + + lruvec = container_of(lrugen, struct lruvec, lrugen); + memcg = lruvec_memcg(lruvec); + + if (!mem_cgroup_tryget(memcg)) { + op = 0; + memcg = NULL; + continue; + } + + rcu_read_unlock(); + + op = shrink_one(lruvec, sc); + + if (sc->nr_reclaimed >= nr_to_reclaim) + goto success; + + rcu_read_lock(); + } + + rcu_read_unlock(); + + /* restart if raced with lru_gen_rotate_memcg() */ + if (gen != get_nulls_value(pos)) + goto restart; + + /* try the rest of the bins of the current generation */ + bin = get_memcg_bin(bin + 1); + if (bin != first_bin) + goto restart; +success: + if (op) + lru_gen_rotate_memcg(lruvec, op); + + mem_cgroup_put(memcg); +} + +static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +{ + struct blk_plug plug; + + VM_WARN_ON_ONCE(global_reclaim(sc)); + + lru_add_drain(); + + blk_start_plug(&plug); + + set_mm_walk(lruvec_pgdat(lruvec)); + + if (try_to_shrink_lruvec(lruvec, sc)) + lru_gen_rotate_memcg(lruvec, MEMCG_LRU_YOUNG); + clear_mm_walk(); blk_finish_plug(&plug); } +#else /* !CONFIG_MEMCG */ + +static void shrink_many(struct pglist_data *pgdat, struct scan_control *sc) +{ + BUILD_BUG(); +} + +static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +{ + BUILD_BUG(); +} + +#endif + +static void set_initial_priority(struct pglist_data *pgdat, struct scan_control *sc) +{ + int priority; + unsigned long reclaimable; + struct lruvec *lruvec = mem_cgroup_lruvec(NULL, pgdat); + + if (sc->priority != DEF_PRIORITY || sc->nr_to_reclaim < MIN_LRU_BATCH) + return; + /* + * Determine the initial priority based on ((total / MEMCG_NR_GENS) >> + * priority) * reclaimed_to_scanned_ratio = nr_to_reclaim, where the + * estimated reclaimed_to_scanned_ratio = inactive / total. + */ + reclaimable = node_page_state(pgdat, NR_INACTIVE_FILE); + if (get_swappiness(lruvec, sc)) + reclaimable += node_page_state(pgdat, NR_INACTIVE_ANON); + + reclaimable /= MEMCG_NR_GENS; + + /* round down reclaimable and round up sc->nr_to_reclaim */ + priority = fls_long(reclaimable) - 1 - fls_long(sc->nr_to_reclaim - 1); + + sc->priority = clamp(priority, 0, DEF_PRIORITY); +} + +static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc) +{ + struct blk_plug plug; + unsigned long reclaimed = sc->nr_reclaimed; + + VM_WARN_ON_ONCE(!global_reclaim(sc)); + + lru_add_drain(); + + blk_start_plug(&plug); + + set_mm_walk(pgdat); + + set_initial_priority(pgdat, sc); + + if (current_is_kswapd()) + sc->nr_reclaimed = 0; + + if (mem_cgroup_disabled()) + shrink_one(&pgdat->__lruvec, sc); + else + shrink_many(pgdat, sc); + + if (current_is_kswapd()) + sc->nr_reclaimed += reclaimed; + + clear_mm_walk(); + + blk_finish_plug(&plug); + + /* kswapd should never fail */ + pgdat->kswapd_failures = 0; +} + +#ifdef CONFIG_MEMCG +void lru_gen_rotate_memcg(struct lruvec *lruvec, int op) +{ + int seg; + int old, new; + int bin = get_random_u32_below(MEMCG_NR_BINS); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + spin_lock(&pgdat->memcg_lru.lock); + + VM_WARN_ON_ONCE(hlist_nulls_unhashed(&lruvec->lrugen.list)); + + seg = 0; + new = old = lruvec->lrugen.gen; + + /* see the comment on MEMCG_NR_GENS */ + if (op == MEMCG_LRU_HEAD) + seg = MEMCG_LRU_HEAD; + else if (op == MEMCG_LRU_TAIL) + seg = MEMCG_LRU_TAIL; + else if (op == MEMCG_LRU_OLD) + new = get_memcg_gen(pgdat->memcg_lru.seq); + else if (op == MEMCG_LRU_YOUNG) + new = get_memcg_gen(pgdat->memcg_lru.seq + 1); + else + VM_WARN_ON_ONCE(true); + + hlist_nulls_del_rcu(&lruvec->lrugen.list); + + if (op == MEMCG_LRU_HEAD || op == MEMCG_LRU_OLD) + hlist_nulls_add_head_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]); + else + hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[new][bin]); + + pgdat->memcg_lru.nr_memcgs[old]--; + pgdat->memcg_lru.nr_memcgs[new]++; + + lruvec->lrugen.gen = new; + WRITE_ONCE(lruvec->lrugen.seg, seg); + + if (!pgdat->memcg_lru.nr_memcgs[old] && old == get_memcg_gen(pgdat->memcg_lru.seq)) + WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1); + + spin_unlock(&pgdat->memcg_lru.lock); +} +#endif + /****************************************************************************** * state change ******************************************************************************/ @@ -5655,11 +5879,11 @@ static int run_cmd(char cmd, int memcg_id, int nid, unsigned long seq, if (!mem_cgroup_disabled()) { rcu_read_lock(); + memcg = mem_cgroup_from_id(memcg_id); -#ifdef CONFIG_MEMCG - if (memcg && !css_tryget(&memcg->css)) + if (!mem_cgroup_tryget(memcg)) memcg = NULL; -#endif + rcu_read_unlock(); if (!memcg) @@ -5807,6 +6031,19 @@ void lru_gen_init_lruvec(struct lruvec *lruvec) } #ifdef CONFIG_MEMCG + +void lru_gen_init_pgdat(struct pglist_data *pgdat) +{ + int i, j; + + spin_lock_init(&pgdat->memcg_lru.lock); + + for (i = 0; i < MEMCG_NR_GENS; i++) { + for (j = 0; j < MEMCG_NR_BINS; j++) + INIT_HLIST_NULLS_HEAD(&pgdat->memcg_lru.fifo[i][j], i); + } +} + void lru_gen_init_memcg(struct mem_cgroup *memcg) { INIT_LIST_HEAD(&memcg->mm_list.fifo); @@ -5830,7 +6067,69 @@ void lru_gen_exit_memcg(struct mem_cgroup *memcg) } } } -#endif + +void lru_gen_online_memcg(struct mem_cgroup *memcg) +{ + int gen; + int nid; + int bin = get_random_u32_below(MEMCG_NR_BINS); + + for_each_node(nid) { + struct pglist_data *pgdat = NODE_DATA(nid); + struct lruvec *lruvec = get_lruvec(memcg, nid); + + spin_lock(&pgdat->memcg_lru.lock); + + VM_WARN_ON_ONCE(!hlist_nulls_unhashed(&lruvec->lrugen.list)); + + gen = get_memcg_gen(pgdat->memcg_lru.seq); + + hlist_nulls_add_tail_rcu(&lruvec->lrugen.list, &pgdat->memcg_lru.fifo[gen][bin]); + pgdat->memcg_lru.nr_memcgs[gen]++; + + lruvec->lrugen.gen = gen; + + spin_unlock(&pgdat->memcg_lru.lock); + } +} + +void lru_gen_offline_memcg(struct mem_cgroup *memcg) +{ + int nid; + + for_each_node(nid) { + struct lruvec *lruvec = get_lruvec(memcg, nid); + + lru_gen_rotate_memcg(lruvec, MEMCG_LRU_OLD); + } +} + +void lru_gen_release_memcg(struct mem_cgroup *memcg) +{ + int gen; + int nid; + + for_each_node(nid) { + struct pglist_data *pgdat = NODE_DATA(nid); + struct lruvec *lruvec = get_lruvec(memcg, nid); + + spin_lock(&pgdat->memcg_lru.lock); + + VM_WARN_ON_ONCE(hlist_nulls_unhashed(&lruvec->lrugen.list)); + + gen = lruvec->lrugen.gen; + + hlist_nulls_del_rcu(&lruvec->lrugen.list); + pgdat->memcg_lru.nr_memcgs[gen]--; + + if (!pgdat->memcg_lru.nr_memcgs[gen] && gen == get_memcg_gen(pgdat->memcg_lru.seq)) + WRITE_ONCE(pgdat->memcg_lru.seq, pgdat->memcg_lru.seq + 1); + + spin_unlock(&pgdat->memcg_lru.lock); + } +} + +#endif /* CONFIG_MEMCG */ static int __init init_lru_gen(void) { @@ -5857,6 +6156,10 @@ static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc { } +static void lru_gen_shrink_node(struct pglist_data *pgdat, struct scan_control *sc) +{ +} + #endif /* CONFIG_LRU_GEN */ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) @@ -5870,7 +6173,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) bool proportional_reclaim; struct blk_plug plug; - if (lru_gen_enabled()) { + if (lru_gen_enabled() && !global_reclaim(sc)) { lru_gen_shrink_lruvec(lruvec, sc); return; } @@ -6113,6 +6416,11 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc) struct lruvec *target_lruvec; bool reclaimable = false; + if (lru_gen_enabled() && global_reclaim(sc)) { + lru_gen_shrink_node(pgdat, sc); + return; + } + target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat); again: -- cgit