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Message-Id: <20171215220450.7899-33-willy@infradead.org>
Date: Fri, 15 Dec 2017 14:04:04 -0800
From: Matthew Wilcox <willy@...radead.org>
To: linux-kernel@...r.kernel.org
Cc: Matthew Wilcox <mawilcox@...rosoft.com>,
Ross Zwisler <ross.zwisler@...ux.intel.com>,
David Howells <dhowells@...hat.com>,
Shaohua Li <shli@...nel.org>, Jens Axboe <axboe@...nel.dk>,
Rehas Sachdeva <aquannie@...il.com>,
Marc Zyngier <marc.zyngier@....com>, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org,
linux-f2fs-devel@...ts.sourceforge.net,
linux-nilfs@...r.kernel.org, linux-btrfs@...r.kernel.org,
linux-xfs@...r.kernel.org, linux-usb@...r.kernel.org,
linux-raid@...r.kernel.org
Subject: [PATCH v5 32/78] mm: Convert workingset to XArray
From: Matthew Wilcox <mawilcox@...rosoft.com>
We construct a fake XA_STATE and use it to delete the node with xa_store()
rather than adding a special function for this unique use case.
Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
include/linux/swap.h | 4 ++--
mm/workingset.c | 49 +++++++++++++++++++++----------------------------
2 files changed, 23 insertions(+), 30 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index c2b8128799c1..e4a8afcb214c 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -300,12 +300,12 @@ bool workingset_refault(void *shadow);
void workingset_activation(struct page *page);
/* Do not use directly, use workingset_lookup_update */
-void workingset_update_node(struct radix_tree_node *node);
+void workingset_update_node(struct xa_node *node);
/* Returns workingset_update_node() if the mapping has shadow entries. */
#define workingset_lookup_update(mapping) \
({ \
- radix_tree_update_node_t __helper = workingset_update_node; \
+ xa_update_node_t __helper = workingset_update_node; \
if (dax_mapping(mapping) || shmem_mapping(mapping)) \
__helper = NULL; \
__helper; \
diff --git a/mm/workingset.c b/mm/workingset.c
index 91b6e16ad4c1..405076233999 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -148,7 +148,7 @@
* and activations is maintained (node->inactive_age).
*
* On eviction, a snapshot of this counter (along with some bits to
- * identify the node) is stored in the now empty page cache radix tree
+ * identify the node) is stored in the now empty page cache
* slot of the evicted page. This is called a shadow entry.
*
* On cache misses for which there are shadow entries, an eligible
@@ -162,7 +162,7 @@
/*
* Eviction timestamps need to be able to cover the full range of
- * actionable refaults. However, bits are tight in the radix tree
+ * actionable refaults. However, bits are tight in the xarray
* entry, and after storing the identifier for the lruvec there might
* not be enough left to represent every single actionable refault. In
* that case, we have to sacrifice granularity for distance, and group
@@ -338,7 +338,7 @@ void workingset_activation(struct page *page)
static struct list_lru shadow_nodes;
-void workingset_update_node(struct radix_tree_node *node)
+void workingset_update_node(struct xa_node *node)
{
/*
* Track non-empty nodes that contain only shadow entries;
@@ -370,7 +370,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
local_irq_enable();
/*
- * Approximate a reasonable limit for the radix tree nodes
+ * Approximate a reasonable limit for the nodes
* containing shadow entries. We don't need to keep more
* shadow entries than possible pages on the active list,
* since refault distances bigger than that are dismissed.
@@ -385,11 +385,11 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
* worst-case density of 1/8th. Below that, not all eligible
* refaults can be detected anymore.
*
- * On 64-bit with 7 radix_tree_nodes per page and 64 slots
+ * On 64-bit with 7 xa_nodes per page and 64 slots
* each, this will reclaim shadow entries when they consume
* ~1.8% of available memory:
*
- * PAGE_SIZE / radix_tree_nodes / node_entries * 8 / PAGE_SIZE
+ * PAGE_SIZE / xa_nodes / node_entries * 8 / PAGE_SIZE
*/
if (sc->memcg) {
cache = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
@@ -408,11 +408,11 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
static enum lru_status shadow_lru_isolate(struct list_head *item,
struct list_lru_one *lru,
spinlock_t *lru_lock,
- void *arg)
+ void *arg) __must_hold(lru_lock)
{
+ XA_STATE(xas, NULL, 0);
struct address_space *mapping;
- struct radix_tree_node *node;
- unsigned int i;
+ struct xa_node *node;
int ret;
/*
@@ -420,7 +420,7 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
* the shadow node LRU under the mapping->pages.xa_lock and the
* lru_lock. Because the page cache tree is emptied before
* the inode can be destroyed, holding the lru_lock pins any
- * address_space that has radix tree nodes on the LRU.
+ * address_space that has nodes on the LRU.
*
* We can then safely transition to the mapping->pages.xa_lock to
* pin only the address_space of the particular node we want
@@ -449,25 +449,18 @@ static enum lru_status shadow_lru_isolate(struct list_head *item,
goto out_invalid;
if (WARN_ON_ONCE(node->count != node->nr_values))
goto out_invalid;
- for (i = 0; i < RADIX_TREE_MAP_SIZE; i++) {
- if (node->slots[i]) {
- if (WARN_ON_ONCE(!xa_is_value(node->slots[i])))
- goto out_invalid;
- if (WARN_ON_ONCE(!node->nr_values))
- goto out_invalid;
- if (WARN_ON_ONCE(!mapping->nrexceptional))
- goto out_invalid;
- node->slots[i] = NULL;
- node->nr_values--;
- node->count--;
- mapping->nrexceptional--;
- }
- }
- if (WARN_ON_ONCE(node->nr_values))
- goto out_invalid;
+ mapping->nrexceptional -= node->nr_values;
+ xas.xa = node->array;
+ xas.xa_node = rcu_dereference_protected(node->parent,
+ lockdep_is_held(&mapping->pages.xa_lock));
+ xas.xa_offset = node->offset;
+ xas.xa_update = workingset_update_node;
+ /*
+ * We could store a shadow entry here which was the minimum of the
+ * shadow entries we were tracking ...
+ */
+ xas_store(&xas, NULL);
inc_lruvec_page_state(virt_to_page(node), WORKINGSET_NODERECLAIM);
- __radix_tree_delete_node(&mapping->pages, node,
- workingset_lookup_update(mapping));
out_invalid:
xa_unlock(&mapping->pages);
--
2.15.1
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