| Message ID | 20220720025920.1373558-8-aneesh.kumar@linux.ibm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/demotion: Memory tiers and demotion | expand |
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes: > From: Jagdish Gediya <jvgediya.oss@gmail.com> > > Currently, a higher tier node can only be demoted to selected > nodes on the next lower tier as defined by the demotion path. > This strict, hard-coded demotion order does not work in all > use cases (e.g. some use cases may want to allow cross-socket > demotion to another node in the same demotion tier as a fallback > when the preferred demotion node is out of space). This demotion > order is also inconsistent with the page allocation fallback order > when all the nodes in a higher tier are out of space: The page > allocation can fall back to any node from any lower tier, whereas > the demotion order doesn't allow that currently. > > This patch adds support to get all the allowed demotion targets > for a memory tier. demote_page_list() function is now modified > to utilize this allowed node mask as the fallback allocation mask. > > Signed-off-by: Jagdish Gediya <jvgediya@linux.ibm.com> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> > --- > include/linux/memory-tiers.h | 11 +++++++ > mm/memory-tiers.c | 54 +++++++++++++++++++++++++++++++-- > mm/vmscan.c | 58 ++++++++++++++++++++++++++---------- > 3 files changed, 106 insertions(+), 17 deletions(-) > > diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h > index 852e86bd0a23..0e58588fa066 100644 > --- a/include/linux/memory-tiers.h > +++ b/include/linux/memory-tiers.h > @@ -19,11 +19,17 @@ > extern bool numa_demotion_enabled; > #ifdef CONFIG_MIGRATION > int next_demotion_node(int node); > +void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets); > #else > static inline int next_demotion_node(int node) > { > return NUMA_NO_NODE; > } > + > +static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) > +{ > + *targets = NODE_MASK_NONE; > +} > #endif > > #else > @@ -33,5 +39,10 @@ static inline int next_demotion_node(int node) > { > return NUMA_NO_NODE; > } > + > +static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) > +{ > + *targets = NODE_MASK_NONE; > +} > #endif /* CONFIG_NUMA */ > #endif /* _LINUX_MEMORY_TIERS_H */ > diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c > index 4715f9b96a44..4a96e4213d66 100644 > --- a/mm/memory-tiers.c > +++ b/mm/memory-tiers.c > @@ -15,6 +15,7 @@ struct memory_tier { > struct list_head list; > int perf_level; > nodemask_t nodelist; > + nodemask_t lower_tier_mask; > }; > > struct demotion_nodes { > @@ -153,6 +154,24 @@ static struct memory_tier *__node_get_memory_tier(int node) > } > > #ifdef CONFIG_MIGRATION > +void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) > +{ > + struct memory_tier *memtier; > + > + /* > + * pg_data_t.memtier updates includes a synchronize_rcu() > + * which ensures that we either find NULL or a valid memtier > + * in NODE_DATA. protect the access via rcu_read_lock(); > + */ > + rcu_read_lock(); > + memtier = rcu_dereference(pgdat->memtier); > + if (memtier) > + *targets = memtier->lower_tier_mask; > + else > + *targets = NODE_MASK_NONE; > + rcu_read_unlock(); > +} > + > /** > * next_demotion_node() - Get the next node in the demotion path > * @node: The starting node to lookup the next node > @@ -201,10 +220,19 @@ int next_demotion_node(int node) > /* Disable reclaim-based migration. */ > static void __disable_all_migrate_targets(void) > { > + struct memory_tier *memtier; > int node; > > - for_each_node_state(node, N_MEMORY) > + for_each_node_state(node, N_MEMORY) { > node_demotion[node].preferred = NODE_MASK_NONE; > + /* > + * We are holding memory_tier_lock, it is safe > + * to access pgda->memtier. > + */ > + memtier = rcu_dereference_check(NODE_DATA(node)->memtier, > + lockdep_is_held(&memory_tier_lock)); > + memtier->lower_tier_mask = NODE_MASK_NONE; > + } > } > > static void disable_all_migrate_targets(void) > @@ -230,7 +258,7 @@ static void establish_migration_targets(void) > struct demotion_nodes *nd; > int target = NUMA_NO_NODE, node; > int distance, best_distance; > - nodemask_t used; > + nodemask_t used, lower_tier = NODE_MASK_NONE; > > if (!node_demotion || !IS_ENABLED(CONFIG_MIGRATION)) > return; > @@ -276,6 +304,28 @@ static void establish_migration_targets(void) > } > } while (1); > } > + /* > + * Now build the lower_tier mask for each node collecting node mask from > + * all memory tier below it. This allows us to fallback demotion page > + * allocation to a set of nodes that is closer the above selected > + * perferred node. > + */ > + list_for_each_entry(memtier, &memory_tiers, list) > + nodes_or(lower_tier, lower_tier, memtier->nodelist); > + /* > + * Removes nodes not yet in N_MEMORY. > + */ > + nodes_and(lower_tier, node_states[N_MEMORY], lower_tier); The above code is equivalent with lower_tier = node_states[N_MEMORY]; ? > + > + list_for_each_entry(memtier, &memory_tiers, list) { > + /* > + * Keep removing current tier from lower_tier nodes, > + * This will remove all nodes in current and above > + * memory tier from the lower_tier mask. > + */ > + nodes_andnot(lower_tier, lower_tier, memtier->nodelist); > + memtier->lower_tier_mask = lower_tier; > + } This is per-memtier instead of per-node. So we need not run this code for each node? That is, move the above code out of for_each_node() loop? Best Regards, Huang, Ying > } > #else > static inline void disable_all_migrate_targets(void) {} > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 3a8f78277f99..60a5235dd639 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1460,21 +1460,34 @@ static void folio_check_dirty_writeback(struct folio *folio, > mapping->a_ops->is_dirty_writeback(folio, dirty, writeback); > } > > -static struct page *alloc_demote_page(struct page *page, unsigned long node) > +static struct page *alloc_demote_page(struct page *page, unsigned long private) > { > - struct migration_target_control mtc = { > - /* > - * Allocate from 'node', or fail quickly and quietly. > - * When this happens, 'page' will likely just be discarded > - * instead of migrated. > - */ > - .gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | > - __GFP_THISNODE | __GFP_NOWARN | > - __GFP_NOMEMALLOC | GFP_NOWAIT, > - .nid = node > - }; > + struct page *target_page; > + nodemask_t *allowed_mask; > + struct migration_target_control *mtc; > + > + mtc = (struct migration_target_control *)private; > + > + allowed_mask = mtc->nmask; > + /* > + * make sure we allocate from the target node first also trying to > + * reclaim pages from the target node via kswapd if we are low on ~~~~~~~ demote or reclaim > + * free memory on target node. If we don't do this and if we have low ~~~~~~~~~~~~~~~~~~ > + * free memory on the target memtier, we would start allocating pages ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ and if we have free memory on the slower(lower) memtier, > + * from higher memory tiers without even forcing a demotion of cold ~~~~~~ slower(lower) > + * pages from the target memtier. This can result in the kernel placing ~~~~~~~ node > + * hotpages in higher memory tiers. ~~~~~~~~ ~~~~~~ hot pages slower(lower) Best Regards, Huang, Ying > + */ > + mtc->nmask = NULL; > + mtc->gfp_mask |= __GFP_THISNODE; > + target_page = alloc_migration_target(page, (unsigned long)mtc); > + if (target_page) > + return target_page; > > - return alloc_migration_target(page, (unsigned long)&mtc); > + mtc->gfp_mask &= ~__GFP_THISNODE; > + mtc->nmask = allowed_mask; > + > + return alloc_migration_target(page, (unsigned long)mtc); > } > > /* > @@ -1487,6 +1500,19 @@ static unsigned int demote_page_list(struct list_head *demote_pages, > { > int target_nid = next_demotion_node(pgdat->node_id); > unsigned int nr_succeeded; > + nodemask_t allowed_mask; > + > + struct migration_target_control mtc = { > + /* > + * Allocate from 'node', or fail quickly and quietly. > + * When this happens, 'page' will likely just be discarded > + * instead of migrated. > + */ > + .gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | __GFP_NOWARN | > + __GFP_NOMEMALLOC | GFP_NOWAIT, > + .nid = target_nid, > + .nmask = &allowed_mask > + }; > > if (list_empty(demote_pages)) > return 0; > @@ -1494,10 +1520,12 @@ static unsigned int demote_page_list(struct list_head *demote_pages, > if (target_nid == NUMA_NO_NODE) > return 0; > > + node_get_allowed_targets(pgdat, &allowed_mask); > + > /* Demotion ignores all cpuset and mempolicy settings */ > migrate_pages(demote_pages, alloc_demote_page, NULL, > - target_nid, MIGRATE_ASYNC, MR_DEMOTION, > - &nr_succeeded); > + (unsigned long)&mtc, MIGRATE_ASYNC, MR_DEMOTION, > + &nr_succeeded); > > if (current_is_kswapd()) > __count_vm_events(PGDEMOTE_KSWAPD, nr_succeeded);
diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h index 852e86bd0a23..0e58588fa066 100644 --- a/include/linux/memory-tiers.h +++ b/include/linux/memory-tiers.h @@ -19,11 +19,17 @@ extern bool numa_demotion_enabled; #ifdef CONFIG_MIGRATION int next_demotion_node(int node); +void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets); #else static inline int next_demotion_node(int node) { return NUMA_NO_NODE; } + +static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) +{ + *targets = NODE_MASK_NONE; +} #endif #else @@ -33,5 +39,10 @@ static inline int next_demotion_node(int node) { return NUMA_NO_NODE; } + +static inline void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) +{ + *targets = NODE_MASK_NONE; +} #endif /* CONFIG_NUMA */ #endif /* _LINUX_MEMORY_TIERS_H */ diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c index 4715f9b96a44..4a96e4213d66 100644 --- a/mm/memory-tiers.c +++ b/mm/memory-tiers.c @@ -15,6 +15,7 @@ struct memory_tier { struct list_head list; int perf_level; nodemask_t nodelist; + nodemask_t lower_tier_mask; }; struct demotion_nodes { @@ -153,6 +154,24 @@ static struct memory_tier *__node_get_memory_tier(int node) } #ifdef CONFIG_MIGRATION +void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) +{ + struct memory_tier *memtier; + + /* + * pg_data_t.memtier updates includes a synchronize_rcu() + * which ensures that we either find NULL or a valid memtier + * in NODE_DATA. protect the access via rcu_read_lock(); + */ + rcu_read_lock(); + memtier = rcu_dereference(pgdat->memtier); + if (memtier) + *targets = memtier->lower_tier_mask; + else + *targets = NODE_MASK_NONE; + rcu_read_unlock(); +} + /** * next_demotion_node() - Get the next node in the demotion path * @node: The starting node to lookup the next node @@ -201,10 +220,19 @@ int next_demotion_node(int node) /* Disable reclaim-based migration. */ static void __disable_all_migrate_targets(void) { + struct memory_tier *memtier; int node; - for_each_node_state(node, N_MEMORY) + for_each_node_state(node, N_MEMORY) { node_demotion[node].preferred = NODE_MASK_NONE; + /* + * We are holding memory_tier_lock, it is safe + * to access pgda->memtier. + */ + memtier = rcu_dereference_check(NODE_DATA(node)->memtier, + lockdep_is_held(&memory_tier_lock)); + memtier->lower_tier_mask = NODE_MASK_NONE; + } } static void disable_all_migrate_targets(void) @@ -230,7 +258,7 @@ static void establish_migration_targets(void) struct demotion_nodes *nd; int target = NUMA_NO_NODE, node; int distance, best_distance; - nodemask_t used; + nodemask_t used, lower_tier = NODE_MASK_NONE; if (!node_demotion || !IS_ENABLED(CONFIG_MIGRATION)) return; @@ -276,6 +304,28 @@ static void establish_migration_targets(void) } } while (1); } + /* + * Now build the lower_tier mask for each node collecting node mask from + * all memory tier below it. This allows us to fallback demotion page + * allocation to a set of nodes that is closer the above selected + * perferred node. + */ + list_for_each_entry(memtier, &memory_tiers, list) + nodes_or(lower_tier, lower_tier, memtier->nodelist); + /* + * Removes nodes not yet in N_MEMORY. + */ + nodes_and(lower_tier, node_states[N_MEMORY], lower_tier); + + list_for_each_entry(memtier, &memory_tiers, list) { + /* + * Keep removing current tier from lower_tier nodes, + * This will remove all nodes in current and above + * memory tier from the lower_tier mask. + */ + nodes_andnot(lower_tier, lower_tier, memtier->nodelist); + memtier->lower_tier_mask = lower_tier; + } } #else static inline void disable_all_migrate_targets(void) {} diff --git a/mm/vmscan.c b/mm/vmscan.c index 3a8f78277f99..60a5235dd639 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1460,21 +1460,34 @@ static void folio_check_dirty_writeback(struct folio *folio, mapping->a_ops->is_dirty_writeback(folio, dirty, writeback); } -static struct page *alloc_demote_page(struct page *page, unsigned long node) +static struct page *alloc_demote_page(struct page *page, unsigned long private) { - struct migration_target_control mtc = { - /* - * Allocate from 'node', or fail quickly and quietly. - * When this happens, 'page' will likely just be discarded - * instead of migrated. - */ - .gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | - __GFP_THISNODE | __GFP_NOWARN | - __GFP_NOMEMALLOC | GFP_NOWAIT, - .nid = node - }; + struct page *target_page; + nodemask_t *allowed_mask; + struct migration_target_control *mtc; + + mtc = (struct migration_target_control *)private; + + allowed_mask = mtc->nmask; + /* + * make sure we allocate from the target node first also trying to + * reclaim pages from the target node via kswapd if we are low on + * free memory on target node. If we don't do this and if we have low + * free memory on the target memtier, we would start allocating pages + * from higher memory tiers without even forcing a demotion of cold + * pages from the target memtier. This can result in the kernel placing + * hotpages in higher memory tiers. + */ + mtc->nmask = NULL; + mtc->gfp_mask |= __GFP_THISNODE; + target_page = alloc_migration_target(page, (unsigned long)mtc); + if (target_page) + return target_page; - return alloc_migration_target(page, (unsigned long)&mtc); + mtc->gfp_mask &= ~__GFP_THISNODE; + mtc->nmask = allowed_mask; + + return alloc_migration_target(page, (unsigned long)mtc); } /* @@ -1487,6 +1500,19 @@ static unsigned int demote_page_list(struct list_head *demote_pages, { int target_nid = next_demotion_node(pgdat->node_id); unsigned int nr_succeeded; + nodemask_t allowed_mask; + + struct migration_target_control mtc = { + /* + * Allocate from 'node', or fail quickly and quietly. + * When this happens, 'page' will likely just be discarded + * instead of migrated. + */ + .gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) | __GFP_NOWARN | + __GFP_NOMEMALLOC | GFP_NOWAIT, + .nid = target_nid, + .nmask = &allowed_mask + }; if (list_empty(demote_pages)) return 0; @@ -1494,10 +1520,12 @@ static unsigned int demote_page_list(struct list_head *demote_pages, if (target_nid == NUMA_NO_NODE) return 0; + node_get_allowed_targets(pgdat, &allowed_mask); + /* Demotion ignores all cpuset and mempolicy settings */ migrate_pages(demote_pages, alloc_demote_page, NULL, - target_nid, MIGRATE_ASYNC, MR_DEMOTION, - &nr_succeeded); + (unsigned long)&mtc, MIGRATE_ASYNC, MR_DEMOTION, + &nr_succeeded); if (current_is_kswapd()) __count_vm_events(PGDEMOTE_KSWAPD, nr_succeeded);