From: Matthew Wilcox <willy@infradead.org>
To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
Jeff Layton <jlayton@redhat.com>,
Lukas Czerner <lczerner@redhat.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Christoph Hellwig <hch@lst.de>,
Goldwyn Rodrigues <rgoldwyn@suse.com>,
Nicholas Piggin <npiggin@gmail.com>,
Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>,
linux-nilfs@vger.kernel.org, Jaegeuk Kim <jaegeuk@kernel.org>,
Chao Yu <yuchao0@huawei.com>,
linux-f2fs-devel@lists.sourceforge.net
Subject: [PATCH v14 05/74] xarray: Change definition of sibling entries
Date: Sat, 16 Jun 2018 18:59:43 -0700 [thread overview]
Message-ID: <20180617020052.4759-6-willy@infradead.org> (raw)
In-Reply-To: <20180617020052.4759-1-willy@infradead.org>
Instead of storing a pointer to the slot containing the canonical entry,
store the offset of the slot. Produces slightly more efficient code
(~300 bytes) and simplifies the implementation.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
include/linux/xarray.h | 93 ++++++++++++++++++++++++++++++++++++++++++
lib/radix-tree.c | 64 +++++++++--------------------
2 files changed, 112 insertions(+), 45 deletions(-)
diff --git a/include/linux/xarray.h b/include/linux/xarray.h
index e6ead6c81458..1ac55c05de14 100644
--- a/include/linux/xarray.h
+++ b/include/linux/xarray.h
@@ -22,6 +22,12 @@
* x1: Value entry
*
* Attempting to store internal entries in the XArray is a bug.
+ *
+ * Most internal entries are pointers to the next node in the tree.
+ * The following internal entries have a special meaning:
+ *
+ * 0-62: Sibling entries
+ * 256: Retry entry
*/
#define BITS_PER_XA_VALUE (BITS_PER_LONG - 1)
@@ -63,6 +69,42 @@ static inline bool xa_is_value(const void *entry)
return (unsigned long)entry & 1;
}
+/*
+ * xa_mk_internal() - Create an internal entry.
+ * @v: Value to turn into an internal entry.
+ *
+ * Context: Any context.
+ * Return: An XArray internal entry corresponding to this value.
+ */
+static inline void *xa_mk_internal(unsigned long v)
+{
+ return (void *)((v << 2) | 2);
+}
+
+/*
+ * xa_to_internal() - Extract the value from an internal entry.
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: The value which was stored in the internal entry.
+ */
+static inline unsigned long xa_to_internal(const void *entry)
+{
+ return (unsigned long)entry >> 2;
+}
+
+/*
+ * xa_is_internal() - Is the entry an internal entry?
+ * @entry: XArray entry.
+ *
+ * Context: Any context.
+ * Return: %true if the entry is an internal entry.
+ */
+static inline bool xa_is_internal(const void *entry)
+{
+ return ((unsigned long)entry & 3) == 2;
+}
+
#define xa_trylock(xa) spin_trylock(&(xa)->xa_lock)
#define xa_lock(xa) spin_lock(&(xa)->xa_lock)
#define xa_unlock(xa) spin_unlock(&(xa)->xa_lock)
@@ -75,4 +117,55 @@ static inline bool xa_is_value(const void *entry)
#define xa_unlock_irqrestore(xa, flags) \
spin_unlock_irqrestore(&(xa)->xa_lock, flags)
+/* Everything below here is the Advanced API. Proceed with caution. */
+
+/*
+ * The xarray is constructed out of a set of 'chunks' of pointers. Choosing
+ * the best chunk size requires some tradeoffs. A power of two recommends
+ * itself so that we can walk the tree based purely on shifts and masks.
+ * Generally, the larger the better; as the number of slots per level of the
+ * tree increases, the less tall the tree needs to be. But that needs to be
+ * balanced against the memory consumption of each node. On a 64-bit system,
+ * xa_node is currently 576 bytes, and we get 7 of them per 4kB page. If we
+ * doubled the number of slots per node, we'd get only 3 nodes per 4kB page.
+ */
+#ifndef XA_CHUNK_SHIFT
+#define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6)
+#endif
+#define XA_CHUNK_SIZE (1UL << XA_CHUNK_SHIFT)
+#define XA_CHUNK_MASK (XA_CHUNK_SIZE - 1)
+
+/* Private */
+static inline bool xa_is_node(const void *entry)
+{
+ return xa_is_internal(entry) && (unsigned long)entry > 4096;
+}
+
+/* Private */
+static inline void *xa_mk_sibling(unsigned int offset)
+{
+ return xa_mk_internal(offset);
+}
+
+/* Private */
+static inline unsigned long xa_to_sibling(const void *entry)
+{
+ return xa_to_internal(entry);
+}
+
+/**
+ * xa_is_sibling() - Is the entry a sibling entry?
+ * @entry: Entry retrieved from the XArray
+ *
+ * Return: %true if the entry is a sibling entry.
+ */
+static inline bool xa_is_sibling(const void *entry)
+{
+ return IS_ENABLED(CONFIG_RADIX_TREE_MULTIORDER) &&
+ xa_is_internal(entry) &&
+ (entry < xa_mk_sibling(XA_CHUNK_SIZE - 1));
+}
+
+#define XA_RETRY_ENTRY xa_mk_internal(256)
+
#endif /* _LINUX_XARRAY_H */
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index fa43dcdc1f6a..22ca63cb3204 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -38,6 +38,7 @@
#include <linux/rcupdate.h>
#include <linux/slab.h>
#include <linux/string.h>
+#include <linux/xarray.h>
/* Number of nodes in fully populated tree of given height */
@@ -98,24 +99,7 @@ static inline void *node_to_entry(void *ptr)
return (void *)((unsigned long)ptr | RADIX_TREE_INTERNAL_NODE);
}
-#define RADIX_TREE_RETRY node_to_entry(NULL)
-
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
-/* Sibling slots point directly to another slot in the same node */
-static inline
-bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
-{
- void __rcu **ptr = node;
- return (parent->slots <= ptr) &&
- (ptr < parent->slots + RADIX_TREE_MAP_SIZE);
-}
-#else
-static inline
-bool is_sibling_entry(const struct radix_tree_node *parent, void *node)
-{
- return false;
-}
-#endif
+#define RADIX_TREE_RETRY XA_RETRY_ENTRY
static inline unsigned long
get_slot_offset(const struct radix_tree_node *parent, void __rcu **slot)
@@ -129,16 +113,10 @@ static unsigned int radix_tree_descend(const struct radix_tree_node *parent,
unsigned int offset = (index >> parent->shift) & RADIX_TREE_MAP_MASK;
void __rcu **entry = rcu_dereference_raw(parent->slots[offset]);
-#ifdef CONFIG_RADIX_TREE_MULTIORDER
- if (radix_tree_is_internal_node(entry)) {
- if (is_sibling_entry(parent, entry)) {
- void __rcu **sibentry;
- sibentry = (void __rcu **) entry_to_node(entry);
- offset = get_slot_offset(parent, sibentry);
- entry = rcu_dereference_raw(*sibentry);
- }
+ if (xa_is_sibling(entry)) {
+ offset = xa_to_sibling(entry);
+ entry = rcu_dereference_raw(parent->slots[offset]);
}
-#endif
*nodep = (void *)entry;
return offset;
@@ -300,10 +278,10 @@ static void dump_node(struct radix_tree_node *node, unsigned long index)
} else if (!radix_tree_is_internal_node(entry)) {
pr_debug("radix entry %p offset %ld indices %lu-%lu parent %p\n",
entry, i, first, last, node);
- } else if (is_sibling_entry(node, entry)) {
+ } else if (xa_is_sibling(entry)) {
pr_debug("radix sblng %p offset %ld indices %lu-%lu parent %p val %p\n",
entry, i, first, last, node,
- *(void **)entry_to_node(entry));
+ node->slots[xa_to_sibling(entry)]);
} else {
dump_node(entry_to_node(entry), first);
}
@@ -873,8 +851,7 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
for (;;) {
void *entry = rcu_dereference_raw(child->slots[offset]);
- if (radix_tree_is_internal_node(entry) &&
- !is_sibling_entry(child, entry)) {
+ if (xa_is_node(entry)) {
child = entry_to_node(entry);
offset = 0;
continue;
@@ -896,7 +873,7 @@ static void radix_tree_free_nodes(struct radix_tree_node *node)
static inline int insert_entries(struct radix_tree_node *node,
void __rcu **slot, void *item, unsigned order, bool replace)
{
- struct radix_tree_node *child;
+ void *sibling;
unsigned i, n, tag, offset, tags = 0;
if (node) {
@@ -914,7 +891,7 @@ static inline int insert_entries(struct radix_tree_node *node,
offset = offset & ~(n - 1);
slot = &node->slots[offset];
}
- child = node_to_entry(slot);
+ sibling = xa_mk_sibling(offset);
for (i = 0; i < n; i++) {
if (slot[i]) {
@@ -931,7 +908,7 @@ static inline int insert_entries(struct radix_tree_node *node,
for (i = 0; i < n; i++) {
struct radix_tree_node *old = rcu_dereference_raw(slot[i]);
if (i) {
- rcu_assign_pointer(slot[i], child);
+ rcu_assign_pointer(slot[i], sibling);
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
tag_clear(node, tag, offset + i);
@@ -941,9 +918,7 @@ static inline int insert_entries(struct radix_tree_node *node,
if (tags & (1 << tag))
tag_set(node, tag, offset);
}
- if (radix_tree_is_internal_node(old) &&
- !is_sibling_entry(node, old) &&
- (old != RADIX_TREE_RETRY))
+ if (xa_is_node(old))
radix_tree_free_nodes(old);
if (xa_is_value(old))
node->exceptional--;
@@ -1102,10 +1077,10 @@ static inline void replace_sibling_entries(struct radix_tree_node *node,
void __rcu **slot, int count, int exceptional)
{
#ifdef CONFIG_RADIX_TREE_MULTIORDER
- void *ptr = node_to_entry(slot);
- unsigned offset = get_slot_offset(node, slot) + 1;
+ unsigned offset = get_slot_offset(node, slot);
+ void *ptr = xa_mk_sibling(offset);
- while (offset < RADIX_TREE_MAP_SIZE) {
+ while (++offset < RADIX_TREE_MAP_SIZE) {
if (rcu_dereference_raw(node->slots[offset]) != ptr)
break;
if (count < 0) {
@@ -1113,7 +1088,6 @@ static inline void replace_sibling_entries(struct radix_tree_node *node,
node->count--;
}
node->exceptional += exceptional;
- offset++;
}
#endif
}
@@ -1312,8 +1286,7 @@ int radix_tree_split(struct radix_tree_root *root, unsigned long index,
tags |= 1 << tag;
for (end = offset + 1; end < RADIX_TREE_MAP_SIZE; end++) {
- if (!is_sibling_entry(parent,
- rcu_dereference_raw(parent->slots[end])))
+ if (!xa_is_sibling(rcu_dereference_raw(parent->slots[end])))
break;
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++)
if (tags & (1 << tag))
@@ -1611,7 +1584,7 @@ static void __rcu **skip_siblings(struct radix_tree_node **nodep,
{
while (iter->index < iter->next_index) {
*nodep = rcu_dereference_raw(*slot);
- if (*nodep && !is_sibling_entry(iter->node, *nodep))
+ if (*nodep && !xa_is_sibling(*nodep))
return slot;
slot++;
iter->index = __radix_tree_iter_add(iter, 1);
@@ -1762,7 +1735,7 @@ void __rcu **radix_tree_next_chunk(const struct radix_tree_root *root,
while (++offset < RADIX_TREE_MAP_SIZE) {
void *slot = rcu_dereference_raw(
node->slots[offset]);
- if (is_sibling_entry(node, slot))
+ if (xa_is_sibling(slot))
continue;
if (slot)
break;
@@ -2283,6 +2256,7 @@ void __init radix_tree_init(void)
BUILD_BUG_ON(RADIX_TREE_MAX_TAGS + __GFP_BITS_SHIFT > 32);
BUILD_BUG_ON(ROOT_IS_IDR & ~GFP_ZONEMASK);
+ BUILD_BUG_ON(XA_CHUNK_SIZE > 255);
radix_tree_node_cachep = kmem_cache_create("radix_tree_node",
sizeof(struct radix_tree_node), 0,
SLAB_PANIC | SLAB_RECLAIM_ACCOUNT,
--
2.17.1
next prev parent reply other threads:[~2018-06-17 1:59 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-17 1:59 [PATCH v14 00/74] Convert page cache to XArray Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 01/74] Update email address Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 02/74] radix tree test suite: Enable ubsan Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 03/74] dax: Fix use of zero page Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 04/74] xarray: Replace exceptional entries Matthew Wilcox
2018-06-17 1:59 ` Matthew Wilcox [this message]
2018-06-17 1:59 ` [PATCH v14 06/74] xarray: Add definition of struct xarray Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 07/74] xarray: Define struct xa_node Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 08/74] xarray: Add documentation Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 09/74] xarray: Add XArray load operation Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 10/74] xarray: Add XArray tags Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 11/74] xarray: Add XArray unconditional store operations Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 12/74] xarray: Add XArray conditional " Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 13/74] xarray: Add XArray iterators Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 14/74] xarray: Extract entries from an XArray Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 15/74] xarray: Destroy " Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 16/74] xarray: Step through " Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 17/74] xarray: Add xas_for_each_conflict Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 18/74] xarray: Add xas_create_range Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 19/74] xarray: Add MAINTAINERS entry Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 20/74] page cache: Rearrange address_space Matthew Wilcox
2018-06-17 1:59 ` [PATCH v14 21/74] page cache: Convert hole search to XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 22/74] page cache: Add and replace pages using the XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 23/74] page cache: Convert page deletion to XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 24/74] page cache: Convert find_get_entry " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 25/74] page cache: Convert find_get_entries " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 26/74] page cache: Convert find_get_pages_range " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 27/74] page cache: Convert find_get_pages_contig " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 28/74] page cache; Convert find_get_pages_range_tag " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 29/74] page cache: Convert find_get_entries_tag " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 30/74] page cache: Convert filemap_map_pages " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 31/74] radix tree test suite: Convert regression1 " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 32/74] page cache: Convert delete_batch " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 33/74] page cache: Remove stray radix comment Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 34/74] page cache: Convert filemap_range_has_page to XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 35/74] mm: Convert page-writeback " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 36/74] mm: Convert workingset " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 37/74] mm: Convert truncate " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 38/74] mm: Convert add_to_swap_cache " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 39/74] mm: Convert delete_from_swap_cache " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 40/74] mm: Convert __do_page_cache_readahead " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 41/74] mm: Convert page migration " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 42/74] mm: Convert huge_memory " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 43/74] mm: Convert collapse_shmem " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 44/74] mm: Convert khugepaged_scan_shmem " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 45/74] mm: Convert is_page_cache_freeable " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 46/74] pagevec: Use xa_tag_t Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 47/74] shmem: Convert shmem_radix_tree_replace to XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 48/74] shmem: Convert shmem_confirm_swap " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 49/74] shmem: Convert find_swap_entry " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 50/74] shmem: Convert shmem_add_to_page_cache " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 51/74] shmem: Convert shmem_alloc_hugepage " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 52/74] shmem: Convert shmem_free_swap " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 53/74] shmem: Convert shmem_partial_swap_usage " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 54/74] memfd: Convert memfd_wait_for_pins " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 55/74] memfd: Convert memfd_tag_pins " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 56/74] shmem: Comment fixups Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 57/74] btrfs: Convert page cache to XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 58/74] fs: Convert buffer " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 59/74] fs: Convert writeback " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 60/74] nilfs2: Convert " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 61/74] f2fs: " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 62/74] dax: Rename some functions Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 63/74] dax: Hash on XArray instead of mapping Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 64/74] dax: Convert dax_insert_pfn_mkwrite to XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 65/74] dax: Convert dax_layout_busy_page " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 66/74] dax: Convert __dax_invalidate_entry " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 67/74] dax: Convert dax writeback " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 68/74] dax: Convert dax_lock_page " Matthew Wilcox
2018-06-29 17:30 ` Ross Zwisler
2018-07-06 11:54 ` [PATCH] fs/dax: remove unused function Anders Roxell
2018-07-06 13:04 ` [PATCH v14 68/74] dax: Convert dax_lock_page to XArray Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 69/74] dax: Convert page fault handlers " Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 70/74] page cache: Finish XArray conversion Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 71/74] radix tree: Remove radix_tree_update_node_t Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 72/74] radix tree: Remove split/join code Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 73/74] radix tree: Remove radix_tree_maybe_preload_order Matthew Wilcox
2018-06-17 2:00 ` [PATCH v14 74/74] radix tree: Remove radix_tree_clear_tags Matthew Wilcox
2018-06-19 3:12 ` [PATCH v14 00/74] Convert page cache to XArray Ross Zwisler
2018-06-19 9:22 ` Matthew Wilcox
2018-06-19 16:40 ` Ross Zwisler
2018-06-19 17:16 ` Matthew Wilcox
2018-06-27 11:05 ` Matthew Wilcox
2018-06-27 19:44 ` Ross Zwisler
2018-06-28 8:39 ` Matthew Wilcox
2018-06-28 16:30 ` Ross Zwisler
2018-07-25 21:03 ` Matthew Wilcox
2018-07-25 21:12 ` Ross Zwisler
2018-07-27 17:20 ` Ross Zwisler
2018-07-30 15:43 ` Matthew Wilcox
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