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Diffstat (limited to 'include/linux/lru_cache.h')
-rw-r--r--include/linux/lru_cache.h67
1 files changed, 43 insertions, 24 deletions
diff --git a/include/linux/lru_cache.h b/include/linux/lru_cache.h
index 7a71ffad037..cbafae40c64 100644
--- a/include/linux/lru_cache.h
+++ b/include/linux/lru_cache.h
@@ -166,9 +166,11 @@ struct lc_element {
/* if we want to track a larger set of objects,
* it needs to become arch independend u64 */
unsigned lc_number;
-
/* special label when on free list */
#define LC_FREE (~0U)
+
+ /* for pending changes */
+ unsigned lc_new_number;
};
struct lru_cache {
@@ -176,6 +178,7 @@ struct lru_cache {
struct list_head lru;
struct list_head free;
struct list_head in_use;
+ struct list_head to_be_changed;
/* the pre-created kmem cache to allocate the objects from */
struct kmem_cache *lc_cache;
@@ -186,7 +189,7 @@ struct lru_cache {
size_t element_off;
/* number of elements (indices) */
- unsigned int nr_elements;
+ unsigned int nr_elements;
/* Arbitrary limit on maximum tracked objects. Practical limit is much
* lower due to allocation failures, probably. For typical use cases,
* nr_elements should be a few thousand at most.
@@ -194,18 +197,19 @@ struct lru_cache {
* 8 high bits of .lc_index to be overloaded with flags in the future. */
#define LC_MAX_ACTIVE (1<<24)
+ /* allow to accumulate a few (index:label) changes,
+ * but no more than max_pending_changes */
+ unsigned int max_pending_changes;
+ /* number of elements currently on to_be_changed list */
+ unsigned int pending_changes;
+
/* statistics */
- unsigned used; /* number of lelements currently on in_use list */
- unsigned long hits, misses, starving, dirty, changed;
+ unsigned used; /* number of elements currently on in_use list */
+ unsigned long hits, misses, starving, locked, changed;
/* see below: flag-bits for lru_cache */
unsigned long flags;
- /* when changing the label of an index element */
- unsigned int new_number;
-
- /* for paranoia when changing the label of an index element */
- struct lc_element *changing_element;
void *lc_private;
const char *name;
@@ -221,10 +225,15 @@ enum {
/* debugging aid, to catch concurrent access early.
* user needs to guarantee exclusive access by proper locking! */
__LC_PARANOIA,
- /* if we need to change the set, but currently there is a changing
- * transaction pending, we are "dirty", and must deferr further
- * changing requests */
+
+ /* annotate that the set is "dirty", possibly accumulating further
+ * changes, until a transaction is finally triggered */
__LC_DIRTY,
+
+ /* Locked, no further changes allowed.
+ * Also used to serialize changing transactions. */
+ __LC_LOCKED,
+
/* if we need to change the set, but currently there is no free nor
* unused element available, we are "starving", and must not give out
* further references, to guarantee that eventually some refcnt will
@@ -236,9 +245,11 @@ enum {
};
#define LC_PARANOIA (1<<__LC_PARANOIA)
#define LC_DIRTY (1<<__LC_DIRTY)
+#define LC_LOCKED (1<<__LC_LOCKED)
#define LC_STARVING (1<<__LC_STARVING)
extern struct lru_cache *lc_create(const char *name, struct kmem_cache *cache,
+ unsigned max_pending_changes,
unsigned e_count, size_t e_size, size_t e_off);
extern void lc_reset(struct lru_cache *lc);
extern void lc_destroy(struct lru_cache *lc);
@@ -249,7 +260,7 @@ extern struct lc_element *lc_try_get(struct lru_cache *lc, unsigned int enr);
extern struct lc_element *lc_find(struct lru_cache *lc, unsigned int enr);
extern struct lc_element *lc_get(struct lru_cache *lc, unsigned int enr);
extern unsigned int lc_put(struct lru_cache *lc, struct lc_element *e);
-extern void lc_changed(struct lru_cache *lc, struct lc_element *e);
+extern void lc_committed(struct lru_cache *lc);
struct seq_file;
extern size_t lc_seq_printf_stats(struct seq_file *seq, struct lru_cache *lc);
@@ -258,32 +269,40 @@ extern void lc_seq_dump_details(struct seq_file *seq, struct lru_cache *lc, char
void (*detail) (struct seq_file *, struct lc_element *));
/**
- * lc_try_lock - can be used to stop lc_get() from changing the tracked set
+ * lc_try_lock_for_transaction - can be used to stop lc_get() from changing the tracked set
* @lc: the lru cache to operate on
*
- * Note that the reference counts and order on the active and lru lists may
- * still change. Returns true if we acquired the lock.
+ * Allows (expects) the set to be "dirty". Note that the reference counts and
+ * order on the active and lru lists may still change. Used to serialize
+ * changing transactions. Returns true if we aquired the lock.
*/
-static inline int lc_try_lock(struct lru_cache *lc)
+static inline int lc_try_lock_for_transaction(struct lru_cache *lc)
{
- return !test_and_set_bit(__LC_DIRTY, &lc->flags);
+ return !test_and_set_bit(__LC_LOCKED, &lc->flags);
}
/**
+ * lc_try_lock - variant to stop lc_get() from changing the tracked set
+ * @lc: the lru cache to operate on
+ *
+ * Note that the reference counts and order on the active and lru lists may
+ * still change. Only works on a "clean" set. Returns true if we aquired the
+ * lock, which means there are no pending changes, and any further attempt to
+ * change the set will not succeed until the next lc_unlock().
+ */
+extern int lc_try_lock(struct lru_cache *lc);
+
+/**
* lc_unlock - unlock @lc, allow lc_get() to change the set again
* @lc: the lru cache to operate on
*/
static inline void lc_unlock(struct lru_cache *lc)
{
clear_bit(__LC_DIRTY, &lc->flags);
- smp_mb__after_clear_bit();
+ clear_bit_unlock(__LC_LOCKED, &lc->flags);
}
-static inline int lc_is_used(struct lru_cache *lc, unsigned int enr)
-{
- struct lc_element *e = lc_find(lc, enr);
- return e && e->refcnt;
-}
+extern bool lc_is_used(struct lru_cache *lc, unsigned int enr);
#define lc_entry(ptr, type, member) \
container_of(ptr, type, member)