diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h index 717a2290acb37..1907098ba908a 100644 --- a/include/linux/mm_inline.h +++ b/include/linux/mm_inline.h @@ -115,6 +115,14 @@ static inline int lru_hist_from_seq(unsigned long seq) return seq % NR_HIST_GENS; } +static inline int lru_tier_from_refs(int refs) +{ + VM_BUG_ON(refs > BIT(LRU_REFS_WIDTH)); + + /* see the comment on MAX_NR_TIERS */ + return order_base_2(refs + 1); +} + static inline bool lru_gen_is_active(struct lruvec *lruvec, int gen) { unsigned long max_seq = lruvec->lrugen.max_seq; @@ -243,6 +251,8 @@ static inline bool lru_gen_del_folio(struct lruvec *lruvec, struct folio *folio, gen = ((new_flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; new_flags &= ~LRU_GEN_MASK; + if ((new_flags & LRU_REFS_FLAGS) != LRU_REFS_FLAGS) + new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); /* for shrink_page_list() */ if (reclaiming) new_flags &= ~(BIT(PG_referenced) | BIT(PG_reclaim)); diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 94af125077882..8f1262bb815a7 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -336,6 +336,25 @@ struct page_vma_mapped_walk; #define MIN_NR_GENS 2U #define MAX_NR_GENS ((unsigned int)CONFIG_NR_LRU_GENS) +/* + * Each generation is divided into multiple tiers. Tiers represent different + * ranges of numbers of accesses thru file descriptors. A page accessed N times + * thru file descriptors is in tier order_base_2(N). A page in the first tier + * (N=0,1) is marked by PG_referenced unless it was faulted in thru page tables + * or read ahead. A page in any other tier (N>1) is marked by PG_referenced and + * PG_workingset. Additional bits in folio->flags are required to support more + * than two tiers. + * + * In contrast to moving across generations (promotion), moving across tiers + * only requires operations on folio->flags and therefore has a negligible cost + * in the buffered access path. In the eviction path, comparisons of + * refaulted/(evicted+promoted) from the first tier and the rest infer whether + * pages accessed multiple times thru file descriptors are statistically hot + * and thus worth promoting. + */ +#define MAX_NR_TIERS ((unsigned int)CONFIG_TIERS_PER_GEN) +#define LRU_REFS_FLAGS (BIT(PG_referenced) | BIT(PG_workingset)) + /* whether to keep historical stats for evicted generations */ #ifdef CONFIG_LRU_GEN_STATS #define NR_HIST_GENS ((unsigned int)CONFIG_NR_LRU_GENS) @@ -354,6 +373,15 @@ struct lru_gen_struct { struct list_head lists[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; /* the sizes of the above lists */ unsigned long nr_pages[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]; + /* the exponential moving average of refaulted */ + unsigned long avg_refaulted[ANON_AND_FILE][MAX_NR_TIERS]; + /* the exponential moving average of evicted+promoted */ + unsigned long avg_total[ANON_AND_FILE][MAX_NR_TIERS]; + /* the first tier doesn't need promotion, hence the minus one */ + unsigned long promoted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS - 1]; + /* can be modified without holding the lru lock */ + atomic_long_t evicted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; + atomic_long_t refaulted[NR_HIST_GENS][ANON_AND_FILE][MAX_NR_TIERS]; /* whether the multigenerational lru is enabled */ bool enabled; }; diff --git a/mm/swap.c b/mm/swap.c index d7dde3b7d4b5f..ae8d568486026 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -407,6 +407,43 @@ static void __lru_cache_activate_folio(struct folio *folio) local_unlock(&lru_pvecs.lock); } +#ifdef CONFIG_LRU_GEN +static void folio_inc_refs(struct folio *folio) +{ + unsigned long refs; + unsigned long old_flags, new_flags; + + if (folio_test_unevictable(folio)) + return; + + /* see the comment on MAX_NR_TIERS */ + do { + new_flags = old_flags = READ_ONCE(folio->flags); + + if (!(new_flags & BIT(PG_referenced))) { + new_flags |= BIT(PG_referenced); + continue; + } + + if (!(new_flags & BIT(PG_workingset))) { + new_flags |= BIT(PG_workingset); + continue; + } + + refs = new_flags & LRU_REFS_MASK; + refs = min(refs + BIT(LRU_REFS_PGOFF), LRU_REFS_MASK); + + new_flags &= ~LRU_REFS_MASK; + new_flags |= refs; + } while (new_flags != old_flags && + cmpxchg(&folio->flags, old_flags, new_flags) != old_flags); +} +#else +static void folio_inc_refs(struct folio *folio) +{ +} +#endif /* CONFIG_LRU_GEN */ + /* * Mark a page as having seen activity. * @@ -419,6 +456,11 @@ static void __lru_cache_activate_folio(struct folio *folio) */ void folio_mark_accessed(struct folio *folio) { + if (lru_gen_enabled()) { + folio_inc_refs(folio); + return; + } + if (!folio_test_referenced(folio)) { folio_set_referenced(folio); } else if (folio_test_unevictable(folio)) { diff --git a/mm/vmscan.c b/mm/vmscan.c index dbbc4038b6034..10bd5385a9660 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -128,6 +128,13 @@ struct scan_control { /* Always discard instead of demoting to lower tier memory */ unsigned int no_demotion:1; +#ifdef CONFIG_LRU_GEN + /* help make better choices when multiple memcgs are eligible */ + unsigned int memcgs_need_aging:1; + unsigned int memcgs_need_swapping:1; + unsigned int memcgs_avoid_swapping:1; +#endif + /* Allocation order */ s8 order; @@ -1288,9 +1295,11 @@ static int __remove_mapping(struct address_space *mapping, struct page *page, if (PageSwapCache(page)) { swp_entry_t swap = { .val = page_private(page) }; - mem_cgroup_swapout(page, swap); + + /* get a shadow entry before mem_cgroup_swapout() clears memcg_data */ if (reclaimed && !mapping_exiting(mapping)) shadow = workingset_eviction(page, target_memcg); + mem_cgroup_swapout(page, swap); __delete_from_swap_cache(page, swap, shadow); xa_unlock_irq(&mapping->i_pages); put_swap_page(page, swap); @@ -2729,6 +2738,9 @@ static void prepare_scan_count(pg_data_t *pgdat, struct scan_control *sc) unsigned long file; struct lruvec *target_lruvec; + if (lru_gen_enabled()) + return; + target_lruvec = mem_cgroup_lruvec(sc->target_mem_cgroup, pgdat); /* @@ -3075,6 +3087,17 @@ static int folio_lru_gen(struct folio *folio) return ((flags & LRU_GEN_MASK) >> LRU_GEN_PGOFF) - 1; } +static int folio_lru_tier(struct folio *folio) +{ + int refs; + unsigned long flags = READ_ONCE(folio->flags); + + refs = (flags & LRU_REFS_FLAGS) == LRU_REFS_FLAGS ? + ((flags & LRU_REFS_MASK) >> LRU_REFS_PGOFF) + 1 : 0; + + return lru_tier_from_refs(refs); +} + static struct lruvec *get_lruvec(struct mem_cgroup *memcg, int nid) { struct pglist_data *pgdat = NODE_DATA(nid); @@ -3453,6 +3476,92 @@ static bool get_next_mm(struct lruvec *lruvec, struct lru_gen_mm_walk *walk, return last; } +/****************************************************************************** + * refault feedback loop + ******************************************************************************/ + +/* + * A feedback loop based on Proportional-Integral-Derivative (PID) controller. + * + * The P term is refaulted/(evicted+promoted) from a tier in the generation + * currently being evicted; the I term is the exponential moving average of the + * P term over the generations previously evicted, using the smoothing factor + * 1/2; the D term isn't used. + * + * The setpoint (SP) is always the first tier of one type; the process variable + * (PV) is either any tier of the other type or any other tier of the same + * type. + * + * The error is the difference between the SP and the PV; the correction is + * turn off promotion when SP>PV or turn on promotion when SPlrugen; + int hist = lru_hist_from_seq(lrugen->min_seq[type]); + + pos->refaulted = lrugen->avg_refaulted[type][tier] + + atomic_long_read(&lrugen->refaulted[hist][type][tier]); + pos->total = lrugen->avg_total[type][tier] + + atomic_long_read(&lrugen->evicted[hist][type][tier]); + if (tier) + pos->total += lrugen->promoted[hist][type][tier - 1]; + pos->gain = gain; +} + +static void reset_ctrl_pos(struct lruvec *lruvec, int gen, int type) +{ + int tier; + int hist = lru_hist_from_seq(gen); + struct lru_gen_struct *lrugen = &lruvec->lrugen; + bool carryover = gen == lru_gen_from_seq(lrugen->min_seq[type]); + bool clear = carryover ? NR_HIST_GENS == 1 : NR_HIST_GENS > 1; + + if (!carryover && !clear) + return; + + for (tier = 0; tier < MAX_NR_TIERS; tier++) { + if (carryover) { + unsigned long sum; + + sum = lrugen->avg_refaulted[type][tier] + + atomic_long_read(&lrugen->refaulted[hist][type][tier]); + WRITE_ONCE(lrugen->avg_refaulted[type][tier], sum / 2); + + sum = lrugen->avg_total[type][tier] + + atomic_long_read(&lrugen->evicted[hist][type][tier]); + if (tier) + sum += lrugen->promoted[hist][type][tier - 1]; + WRITE_ONCE(lrugen->avg_total[type][tier], sum / 2); + } + + if (clear) { + atomic_long_set(&lrugen->refaulted[hist][type][tier], 0); + atomic_long_set(&lrugen->evicted[hist][type][tier], 0); + if (tier) + WRITE_ONCE(lrugen->promoted[hist][type][tier - 1], 0); + } + } +} + +static bool positive_ctrl_err(struct ctrl_pos *sp, struct ctrl_pos *pv) +{ + /* + * Return true if the PV has a limited number of refaults or a lower + * refaulted/total than the SP. + */ + return pv->refaulted < MIN_LRU_BATCH || + pv->refaulted * (sp->total + MIN_LRU_BATCH) * sp->gain <= + (sp->refaulted + 1) * pv->total * pv->gain; +} + /****************************************************************************** * the aging ******************************************************************************/ @@ -3476,6 +3585,7 @@ static void folio_update_gen(struct folio *folio, struct lru_gen_mm_walk *walk) new_flags &= ~LRU_GEN_MASK; new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF; + new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); } while (new_flags != old_flags && cmpxchg(&folio->flags, old_flags, new_flags) != old_flags); @@ -3508,6 +3618,7 @@ static int folio_inc_gen(struct lruvec *lruvec, struct folio *folio, bool reclai new_flags &= ~LRU_GEN_MASK; new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF; + new_flags &= ~(LRU_REFS_MASK | LRU_REFS_FLAGS); /* for folio_end_writeback() */ if (reclaiming) new_flags |= BIT(PG_reclaim); @@ -3961,6 +4072,8 @@ static void inc_min_seq(struct lruvec *lruvec) if (get_nr_gens(lruvec, type) != MAX_NR_GENS) continue; + gen = lru_gen_from_seq(lrugen->min_seq[type]); + reset_ctrl_pos(lruvec, gen, type); WRITE_ONCE(lrugen->min_seq[type], lrugen->min_seq[type] + 1); } } @@ -3999,6 +4112,8 @@ static bool try_to_inc_min_seq(struct lruvec *lruvec, bool can_swap) if (min_seq[type] == lrugen->min_seq[type]) continue; + gen = lru_gen_from_seq(lrugen->min_seq[type]); + reset_ctrl_pos(lruvec, gen, type); WRITE_ONCE(lrugen->min_seq[type], min_seq[type]); success = true; } @@ -4039,6 +4154,9 @@ static void inc_max_seq(struct lruvec *lruvec, unsigned long max_seq) } } + for (type = 0; type < ANON_AND_FILE; type++) + reset_ctrl_pos(lruvec, next, type); + WRITE_ONCE(lrugen->timestamps[next], jiffies); /* make sure preceding modifications appear */ smp_store_release(&lrugen->max_seq, lrugen->max_seq + 1); @@ -4189,6 +4307,22 @@ static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) VM_BUG_ON(!current_is_kswapd()); + /* + * To avoid the aging path and reduce the chance of swapping, which can + * be costly, optimistically skip them unless their corresponding flags + * were cleared in the eviction path. This improves the overall + * performance when multiple memcgs are eligible. + */ + if (!sc->memcgs_need_aging) { + sc->memcgs_need_aging = 1; + sc->memcgs_avoid_swapping = !sc->memcgs_need_swapping; + sc->memcgs_need_swapping = 1; + return; + } + + sc->memcgs_need_swapping = 1; + sc->memcgs_avoid_swapping = 1; + current->reclaim_state->mm_walk = &pgdat->mm_walk; memcg = mem_cgroup_iter(NULL, NULL, NULL); @@ -4316,6 +4450,429 @@ void lru_gen_look_around(struct page_vma_mapped_walk *pvmw) bitmap_zero(walk->bitmap, MIN_LRU_BATCH); } +/****************************************************************************** + * the eviction + ******************************************************************************/ + +static bool sort_folio(struct lruvec *lruvec, struct folio *folio, int tier_idx) +{ + bool success; + int gen = folio_lru_gen(folio); + int type = folio_is_file_lru(folio); + int zone = folio_zonenum(folio); + int tier = folio_lru_tier(folio); + int delta = folio_nr_pages(folio); + struct lru_gen_struct *lrugen = &lruvec->lrugen; + + VM_BUG_ON_FOLIO(gen >= MAX_NR_GENS, folio); + + if (!folio_evictable(folio)) { + success = lru_gen_del_folio(lruvec, folio, true); + VM_BUG_ON_FOLIO(!success, folio); + folio_set_unevictable(folio); + lruvec_add_folio(lruvec, folio); + __count_vm_events(UNEVICTABLE_PGCULLED, delta); + return true; + } + + if (type && folio_test_anon(folio) && folio_test_dirty(folio)) { + success = lru_gen_del_folio(lruvec, folio, true); + VM_BUG_ON_FOLIO(!success, folio); + folio_set_swapbacked(folio); + lruvec_add_folio_tail(lruvec, folio); + return true; + } + + if (gen != lru_gen_from_seq(lrugen->min_seq[type])) { + list_move(&folio->lru, &lrugen->lists[gen][type][zone]); + return true; + } + + if (tier > tier_idx) { + int hist = lru_hist_from_seq(gen); + + gen = folio_inc_gen(lruvec, folio, false); + list_move_tail(&folio->lru, &lrugen->lists[gen][type][zone]); + + WRITE_ONCE(lrugen->promoted[hist][type][tier - 1], + lrugen->promoted[hist][type][tier - 1] + delta); + __mod_lruvec_state(lruvec, WORKINGSET_ACTIVATE_BASE + type, delta); + return true; + } + + if (folio_test_writeback(folio) || (type && folio_test_dirty(folio))) { + gen = folio_inc_gen(lruvec, folio, true); + list_move(&folio->lru, &lrugen->lists[gen][type][zone]); + return true; + } + + return false; +} + +static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct scan_control *sc) +{ + bool success; + + if (!sc->may_unmap && folio_mapped(folio)) + return false; + + if (!(sc->may_writepage && (sc->gfp_mask & __GFP_IO)) && + (folio_test_dirty(folio) || + (folio_test_anon(folio) && !folio_test_swapcache(folio)))) + return false; + + if (!folio_try_get(folio)) + return false; + + if (!folio_test_clear_lru(folio)) { + folio_put(folio); + return false; + } + + success = lru_gen_del_folio(lruvec, folio, true); + VM_BUG_ON_FOLIO(!success, folio); + + return true; +} + +static int scan_folios(struct lruvec *lruvec, struct scan_control *sc, + int type, int tier, struct list_head *list) +{ + int gen, zone; + enum vm_event_item item; + int sorted = 0; + int scanned = 0; + int isolated = 0; + int remaining = MAX_LRU_BATCH; + struct lru_gen_struct *lrugen = &lruvec->lrugen; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + + VM_BUG_ON(!list_empty(list)); + + if (get_nr_gens(lruvec, type) == MIN_NR_GENS) + return 0; + + gen = lru_gen_from_seq(lrugen->min_seq[type]); + + for (zone = sc->reclaim_idx; zone >= 0; zone--) { + LIST_HEAD(moved); + int skipped = 0; + struct list_head *head = &lrugen->lists[gen][type][zone]; + + while (!list_empty(head)) { + struct folio *folio = lru_to_folio(head); + int delta = folio_nr_pages(folio); + + VM_BUG_ON_FOLIO(folio_test_unevictable(folio), folio); + VM_BUG_ON_FOLIO(folio_test_active(folio), folio); + VM_BUG_ON_FOLIO(folio_is_file_lru(folio) != type, folio); + VM_BUG_ON_FOLIO(folio_zonenum(folio) != zone, folio); + + scanned += delta; + + if (sort_folio(lruvec, folio, tier)) + sorted += delta; + else if (isolate_folio(lruvec, folio, sc)) { + list_add(&folio->lru, list); + isolated += delta; + } else { + list_move(&folio->lru, &moved); + skipped += delta; + } + + if (!--remaining || max(isolated, skipped) >= MIN_LRU_BATCH) + break; + } + + if (skipped) { + list_splice(&moved, head); + __count_zid_vm_events(PGSCAN_SKIP, zone, skipped); + } + + if (!remaining || isolated >= MIN_LRU_BATCH) + break; + } + + item = current_is_kswapd() ? PGSCAN_KSWAPD : PGSCAN_DIRECT; + if (!cgroup_reclaim(sc)) { + __count_vm_events(item, isolated); + __count_vm_events(PGREFILL, sorted); + } + __count_memcg_events(memcg, item, isolated); + __count_memcg_events(memcg, PGREFILL, sorted); + __count_vm_events(PGSCAN_ANON + type, isolated); + + /* + * There might not be eligible pages due to reclaim_idx, may_unmap and + * may_writepage. Check the remaining to prevent livelock if there is no + * progress. + */ + return isolated || !remaining ? scanned : 0; +} + +static int get_tier_idx(struct lruvec *lruvec, int type) +{ + int tier; + struct ctrl_pos sp, pv; + + /* + * To leave a margin for fluctuations, use a larger gain factor (1:2). + * This value is chosen because any other tier would have at least twice + * as many refaults as the first tier. + */ + read_ctrl_pos(lruvec, type, 0, 1, &sp); + for (tier = 1; tier < MAX_NR_TIERS; tier++) { + read_ctrl_pos(lruvec, type, tier, 2, &pv); + if (!positive_ctrl_err(&sp, &pv)) + break; + } + + return tier - 1; +} + +static int get_type_to_scan(struct lruvec *lruvec, int swappiness, int *tier_idx) +{ + int type, tier; + struct ctrl_pos sp, pv; + int gain[ANON_AND_FILE] = { swappiness, 200 - swappiness }; + + /* + * Compare the first tier of anon with that of file to determine which + * type to scan. Also need to compare other tiers of the selected type + * with the first tier of the other type to determine the last tier (of + * the selected type) to evict. + */ + read_ctrl_pos(lruvec, 0, 0, gain[0], &sp); + read_ctrl_pos(lruvec, 1, 0, gain[1], &pv); + type = positive_ctrl_err(&sp, &pv); + + read_ctrl_pos(lruvec, !type, 0, gain[!type], &sp); + for (tier = 1; tier < MAX_NR_TIERS; tier++) { + read_ctrl_pos(lruvec, type, tier, gain[type], &pv); + if (!positive_ctrl_err(&sp, &pv)) + break; + } + + *tier_idx = tier - 1; + + return type; +} + +static int isolate_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness, + int *type_scanned, struct list_head *list) +{ + int i; + int type; + int scanned; + int tier = -1; + DEFINE_MIN_SEQ(lruvec); + + VM_BUG_ON(!seq_is_valid(lruvec)); + + /* + * Try to make the obvious choice first. When anon and file are both + * available from the same generation, interpret swappiness 1 as file + * first and 200 as anon first. + */ + if (!swappiness) + type = 1; + else if (min_seq[0] < min_seq[1]) + type = 0; + else if (swappiness == 1) + type = 1; + else if (swappiness == 200) + type = 0; + else + type = get_type_to_scan(lruvec, swappiness, &tier); + + for (i = !swappiness; i < ANON_AND_FILE; i++) { + if (tier < 0) + tier = get_tier_idx(lruvec, type); + + scanned = scan_folios(lruvec, sc, type, tier, list); + if (scanned) + break; + + type = !type; + tier = -1; + } + + *type_scanned = type; + + return scanned; +} + +static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swappiness, + bool *swapped) +{ + int type; + int scanned; + int reclaimed; + LIST_HEAD(list); + struct folio *folio; + enum vm_event_item item; + struct reclaim_stat stat; + struct lru_gen_mm_walk *walk; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + spin_lock_irq(&lruvec->lru_lock); + + scanned = isolate_folios(lruvec, sc, swappiness, &type, &list); + + if (try_to_inc_min_seq(lruvec, swappiness)) + scanned++; + + if (get_nr_gens(lruvec, 1) == MIN_NR_GENS) + scanned = 0; + + spin_unlock_irq(&lruvec->lru_lock); + + if (list_empty(&list)) + return scanned; + + reclaimed = shrink_page_list(&list, pgdat, sc, &stat, false); + + /* + * To avoid livelock, don't add rejected pages back to the same lists + * they were isolated from. + */ + list_for_each_entry(folio, &list, lru) { + if (!folio_test_reclaim(folio) || + !(folio_test_dirty(folio) || folio_test_writeback(folio))) + folio_set_active(folio); + + folio_clear_referenced(folio); + folio_clear_workingset(folio); + } + + spin_lock_irq(&lruvec->lru_lock); + + move_pages_to_lru(lruvec, &list); + + walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL; + if (walk && walk->batched) + reset_batch_size(lruvec, walk); + + item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT; + if (!cgroup_reclaim(sc)) + __count_vm_events(item, reclaimed); + __count_memcg_events(memcg, item, reclaimed); + __count_vm_events(PGSTEAL_ANON + type, reclaimed); + + spin_unlock_irq(&lruvec->lru_lock); + + mem_cgroup_uncharge_list(&list); + free_unref_page_list(&list); + + sc->nr_reclaimed += reclaimed; + + if (!type && swapped) + *swapped = true; + + return scanned; +} + +static long get_nr_to_scan(struct lruvec *lruvec, struct scan_control *sc, bool can_swap) +{ + bool need_aging; + long nr_to_scan; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + DEFINE_MAX_SEQ(lruvec); + DEFINE_MIN_SEQ(lruvec); + + if (mem_cgroup_below_min(memcg) || + (mem_cgroup_below_low(memcg) && !sc->memcg_low_reclaim)) + return 0; + + nr_to_scan = get_nr_evictable(lruvec, max_seq, min_seq, sc, can_swap, &need_aging); + if (!nr_to_scan) + return 0; + + nr_to_scan >>= sc->priority; + + if (!mem_cgroup_online(memcg)) + nr_to_scan++; + + if (!nr_to_scan) + return 0; + + if (current_is_kswapd()) { + /* leave the work to lru_gen_age_node() */ + if (need_aging) + return 0; + + sc->memcgs_need_aging = 0; + return nr_to_scan; + } + + if (max_seq >= min_seq[1] + MIN_NR_GENS) + return nr_to_scan; + + /* try slab and other memcgs before going to the aging path */ + if (!sc->force_deactivate) { + sc->skipped_deactivate = 1; + return 0; + } + + return try_to_inc_max_seq(lruvec, max_seq, sc, can_swap, false) ? nr_to_scan : 0; +} + +static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +{ + struct blk_plug plug; + long scanned = 0; + bool swapped = false; + unsigned long reclaimed = sc->nr_reclaimed; + struct mem_cgroup *memcg = lruvec_memcg(lruvec); + struct pglist_data *pgdat = lruvec_pgdat(lruvec); + + lru_add_drain(); + + if (current_is_kswapd()) + current->reclaim_state->mm_walk = &pgdat->mm_walk; + + blk_start_plug(&plug); + + while (true) { + int delta; + int swappiness; + long nr_to_scan; + + if (sc->may_swap) + swappiness = get_swappiness(memcg); + else if (!cgroup_reclaim(sc) && get_swappiness(memcg)) + swappiness = 1; + else + swappiness = 0; + + nr_to_scan = get_nr_to_scan(lruvec, sc, swappiness); + if (!nr_to_scan) + break; + + delta = evict_folios(lruvec, sc, swappiness, &swapped); + if (!delta) + break; + + if (sc->memcgs_avoid_swapping && swappiness < 200 && swapped) + break; + + scanned += delta; + if (scanned >= nr_to_scan) { + if (!swapped && sc->nr_reclaimed - reclaimed >= MIN_LRU_BATCH) + sc->memcgs_need_swapping = 0; + break; + } + + cond_resched(); + } + + blk_finish_plug(&plug); + + if (current_is_kswapd()) + current->reclaim_state->mm_walk = NULL; +} + /****************************************************************************** * state change ******************************************************************************/ @@ -4540,6 +5097,10 @@ static void lru_gen_age_node(struct pglist_data *pgdat, struct scan_control *sc) { } +static void lru_gen_shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) +{ +} + #endif /* CONFIG_LRU_GEN */ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) @@ -4553,6 +5114,11 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc) struct blk_plug plug; bool scan_adjusted; + if (lru_gen_enabled()) { + lru_gen_shrink_lruvec(lruvec, sc); + return; + } + get_scan_count(lruvec, sc, nr); /* Record the original scan target for proportional adjustments later */ @@ -5057,6 +5623,9 @@ static void snapshot_refaults(struct mem_cgroup *target_memcg, pg_data_t *pgdat) struct lruvec *target_lruvec; unsigned long refaults; + if (lru_gen_enabled()) + return; + target_lruvec = mem_cgroup_lruvec(target_memcg, pgdat); refaults = lruvec_page_state(target_lruvec, WORKINGSET_ACTIVATE_ANON); target_lruvec->refaults[0] = refaults; diff --git a/mm/workingset.c b/mm/workingset.c index 8c03afe1d67cb..c2e433d76de17 100644 --- a/mm/workingset.c +++ b/mm/workingset.c @@ -187,7 +187,6 @@ static unsigned int bucket_order __read_mostly; static void *pack_shadow(int memcgid, pg_data_t *pgdat, unsigned long eviction, bool workingset) { - eviction >>= bucket_order; eviction &= EVICTION_MASK; eviction = (eviction << MEM_CGROUP_ID_SHIFT) | memcgid; eviction = (eviction << NODES_SHIFT) | pgdat->node_id; @@ -212,10 +211,116 @@ static void unpack_shadow(void *shadow, int *memcgidp, pg_data_t **pgdat, *memcgidp = memcgid; *pgdat = NODE_DATA(nid); - *evictionp = entry << bucket_order; + *evictionp = entry; *workingsetp = workingset; } +#ifdef CONFIG_LRU_GEN + +static int folio_lru_refs(struct folio *folio) +{ + unsigned long flags = READ_ONCE(folio->flags); + + BUILD_BUG_ON(LRU_GEN_WIDTH + LRU_REFS_WIDTH > BITS_PER_LONG - EVICTION_SHIFT); + + /* see the comment on MAX_NR_TIERS */ + return flags & BIT(PG_workingset) ? (flags & LRU_REFS_MASK) >> LRU_REFS_PGOFF : 0; +} + +static void *lru_gen_eviction(struct folio *folio) +{ + int hist, tier; + unsigned long token; + unsigned long min_seq; + struct lruvec *lruvec; + struct lru_gen_struct *lrugen; + int type = folio_is_file_lru(folio); + int refs = folio_lru_refs(folio); + int delta = folio_nr_pages(folio); + bool workingset = folio_test_workingset(folio); + struct mem_cgroup *memcg = folio_memcg(folio); + struct pglist_data *pgdat = folio_pgdat(folio); + + lruvec = mem_cgroup_lruvec(memcg, pgdat); + lrugen = &lruvec->lrugen; + min_seq = READ_ONCE(lrugen->min_seq[type]); + token = (min_seq << LRU_REFS_WIDTH) | refs; + + hist = lru_hist_from_seq(min_seq); + tier = lru_tier_from_refs(refs + workingset); + atomic_long_add(delta, &lrugen->evicted[hist][type][tier]); + + return pack_shadow(mem_cgroup_id(memcg), pgdat, token, workingset); +} + +static void lru_gen_refault(struct folio *folio, void *shadow) +{ + int hist, tier, refs; + int memcg_id; + bool workingset; + unsigned long token; + unsigned long min_seq; + struct lruvec *lruvec; + struct lru_gen_struct *lrugen; + struct mem_cgroup *memcg; + struct pglist_data *pgdat; + int type = folio_is_file_lru(folio); + int delta = folio_nr_pages(folio); + + unpack_shadow(shadow, &memcg_id, &pgdat, &token, &workingset); + + refs = token & (BIT(LRU_REFS_WIDTH) - 1); + if (refs && !workingset) + return; + + if (folio_pgdat(folio) != pgdat) + return; + + rcu_read_lock(); + memcg = folio_memcg_rcu(folio); + if (mem_cgroup_id(memcg) != memcg_id) + goto unlock; + + token >>= LRU_REFS_WIDTH; + lruvec = mem_cgroup_lruvec(memcg, pgdat); + lrugen = &lruvec->lrugen; + min_seq = READ_ONCE(lrugen->min_seq[type]); + if (token != (min_seq & (EVICTION_MASK >> LRU_REFS_WIDTH))) + goto unlock; + + hist = lru_hist_from_seq(min_seq); + tier = lru_tier_from_refs(refs + workingset); + atomic_long_add(delta, &lrugen->refaulted[hist][type][tier]); + mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + type, delta); + + /* + * Count the following two cases as stalls: + * 1) For pages accessed thru page tables, hotter pages pushed out hot + * pages which refaulted immediately. + * 2) For pages accessed thru file descriptors, numbers of accesses + * might have been beyond the limit. + */ + if (task_in_lru_fault() || refs + workingset == BIT(LRU_REFS_WIDTH)) { + folio_set_workingset(folio); + mod_lruvec_state(lruvec, WORKINGSET_RESTORE_BASE + type, delta); + } +unlock: + rcu_read_unlock(); +} + +#else + +static void *lru_gen_eviction(struct folio *folio) +{ + return NULL; +} + +static void lru_gen_refault(struct folio *folio, void *shadow) +{ +} + +#endif /* CONFIG_LRU_GEN */ + /** * workingset_age_nonresident - age non-resident entries as LRU ages * @lruvec: the lruvec that was aged @@ -264,10 +369,14 @@ void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg) VM_BUG_ON_PAGE(page_count(page), page); VM_BUG_ON_PAGE(!PageLocked(page), page); + if (lru_gen_enabled()) + return lru_gen_eviction(page_folio(page)); + lruvec = mem_cgroup_lruvec(target_memcg, pgdat); /* XXX: target_memcg can be NULL, go through lruvec */ memcgid = mem_cgroup_id(lruvec_memcg(lruvec)); eviction = atomic_long_read(&lruvec->nonresident_age); + eviction >>= bucket_order; workingset_age_nonresident(lruvec, thp_nr_pages(page)); return pack_shadow(memcgid, pgdat, eviction, PageWorkingset(page)); } @@ -297,7 +406,13 @@ void workingset_refault(struct folio *folio, void *shadow) int memcgid; long nr; + if (lru_gen_enabled()) { + lru_gen_refault(folio, shadow); + return; + } + unpack_shadow(shadow, &memcgid, &pgdat, &eviction, &workingset); + eviction <<= bucket_order; rcu_read_lock(); /*