[TIPC]: Optimized initialization of TIPC reference table
This patch modifies TIPC's reference table code to delay initializing table entries until they are actually needed by applications. Signed-off-by: Allan Stephens <allan.stephens@windriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Allan Stephens
David S. Miller
Родитель
4784b7c348
Коммит
0089509826
123
net/tipc/ref.c
123
net/tipc/ref.c
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@ -50,7 +50,7 @@
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* struct reference - TIPC object reference entry
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* @object: pointer to object associated with reference entry
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* @lock: spinlock controlling access to object
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* @data: reference value associated with object (or link to next unused entry)
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* @data: reference value for object (combines instance & array index info)
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*/
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struct reference {
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@ -65,31 +65,40 @@ struct reference {
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/**
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* struct tipc_ref_table - table of TIPC object reference entries
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* @entries: pointer to array of reference entries
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* @index_mask: bitmask for array index portion of reference values
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* @capacity: array index of first unusable entry
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* @init_point: array index of first uninitialized entry
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* @first_free: array index of first unused object reference entry
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* @last_free: array index of last unused object reference entry
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* @index_mask: bitmask for array index portion of reference values
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* @start_mask: initial value for instance value portion of reference values
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*/
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struct ref_table {
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struct reference *entries;
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u32 index_mask;
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u32 capacity;
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u32 init_point;
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u32 first_free;
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u32 last_free;
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u32 index_mask;
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u32 start_mask;
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};
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/*
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* Object reference table consists of 2**N entries.
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*
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* A used entry has object ptr != 0, reference == XXXX|own index
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* (XXXX changes each time entry is acquired)
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* A free entry has object ptr == 0, reference == YYYY|next free index
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* (YYYY is one more than last used XXXX)
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* State Object ptr Reference
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* ----- ---------- ---------
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* In use non-NULL XXXX|own index
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* (XXXX changes each time entry is acquired)
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* Free NULL YYYY|next free index
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* (YYYY is one more than last used XXXX)
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* Uninitialized NULL 0
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*
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* Free list is initially chained from entry (2**N)-1 to entry 1.
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* Entry 0 is not used to allow index 0 to indicate the end of the free list.
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* Entry 0 is not used; this allows index 0 to denote the end of the free list.
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*
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* Note: Any accidental reference of the form XXXX|0--0 won't match entry 0
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* because entry 0's reference field has the form XXXX|1--1.
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* Note that a reference value of 0 does not necessarily indicate that an
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* entry is uninitialized, since the last entry in the free list could also
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* have a reference value of 0 (although this is unlikely).
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*/
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static struct ref_table tipc_ref_table = { NULL };
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@ -103,29 +112,29 @@ static DEFINE_RWLOCK(ref_table_lock);
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int tipc_ref_table_init(u32 requested_size, u32 start)
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{
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struct reference *table;
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u32 sz = 1 << 4;
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u32 index_mask;
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int i;
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u32 actual_size;
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while (sz < requested_size) {
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sz <<= 1;
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}
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table = vmalloc(sz * sizeof(*table));
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/* account for unused entry, then round up size to a power of 2 */
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requested_size++;
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for (actual_size = 16; actual_size < requested_size; actual_size <<= 1)
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/* do nothing */ ;
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/* allocate table & mark all entries as uninitialized */
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table = __vmalloc(actual_size * sizeof(struct reference),
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GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
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if (table == NULL)
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return -ENOMEM;
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write_lock_bh(&ref_table_lock);
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index_mask = sz - 1;
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for (i = sz - 1; i >= 0; i--) {
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table[i].object = NULL;
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spin_lock_init(&table[i].lock);
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table[i].data.next_plus_upper = (start & ~index_mask) + i - 1;
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}
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tipc_ref_table.entries = table;
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tipc_ref_table.index_mask = index_mask;
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tipc_ref_table.first_free = sz - 1;
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tipc_ref_table.last_free = 1;
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write_unlock_bh(&ref_table_lock);
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tipc_ref_table.capacity = requested_size;
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tipc_ref_table.init_point = 1;
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tipc_ref_table.first_free = 0;
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tipc_ref_table.last_free = 0;
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tipc_ref_table.index_mask = actual_size - 1;
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tipc_ref_table.start_mask = start & ~tipc_ref_table.index_mask;
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return TIPC_OK;
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}
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@ -156,7 +165,7 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock)
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u32 index;
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u32 index_mask;
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u32 next_plus_upper;
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u32 reference = 0;
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u32 reference;
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if (!object) {
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err("Attempt to acquire reference to non-existent object\n");
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@ -167,6 +176,8 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock)
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return 0;
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}
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/* take a free entry, if available; otherwise initialize a new entry */
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write_lock_bh(&ref_table_lock);
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if (tipc_ref_table.first_free) {
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index = tipc_ref_table.first_free;
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@ -179,11 +190,23 @@ u32 tipc_ref_acquire(void *object, spinlock_t **lock)
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reference = (next_plus_upper & ~index_mask) + index;
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entry->data.reference = reference;
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entry->object = object;
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if (lock != NULL)
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*lock = &entry->lock;
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spin_unlock_bh(&entry->lock);
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*lock = &entry->lock;
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}
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else if (tipc_ref_table.init_point < tipc_ref_table.capacity) {
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index = tipc_ref_table.init_point++;
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entry = &(tipc_ref_table.entries[index]);
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spin_lock_init(&entry->lock);
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reference = tipc_ref_table.start_mask + index;
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entry->data.reference = reference;
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entry->object = object;
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*lock = &entry->lock;
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}
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else {
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reference = 0;
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}
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write_unlock_bh(&ref_table_lock);
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return reference;
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}
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@ -200,20 +223,17 @@ void tipc_ref_discard(u32 ref)
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u32 index;
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u32 index_mask;
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if (!ref) {
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err("Attempt to discard reference 0\n");
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return;
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}
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if (!tipc_ref_table.entries) {
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err("Reference table not found during discard attempt\n");
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return;
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}
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write_lock_bh(&ref_table_lock);
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index_mask = tipc_ref_table.index_mask;
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index = ref & index_mask;
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entry = &(tipc_ref_table.entries[index]);
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write_lock_bh(&ref_table_lock);
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if (!entry->object) {
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err("Attempt to discard reference to non-existent object\n");
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goto exit;
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@ -223,18 +243,23 @@ void tipc_ref_discard(u32 ref)
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goto exit;
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}
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/* mark entry as unused */
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/*
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* mark entry as unused; increment upper bits of entry's data field
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* to invalidate any subsequent references
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*/
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entry->object = NULL;
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entry->data.next_plus_upper = (ref & ~index_mask) + (index_mask + 1);
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/* append entry to free entry list */
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if (tipc_ref_table.first_free == 0)
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tipc_ref_table.first_free = index;
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else
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/* next_plus_upper is always XXXX|0--0 for last free entry */
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tipc_ref_table.entries[tipc_ref_table.last_free].
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data.next_plus_upper |= index;
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tipc_ref_table.last_free = index;
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/* increment upper bits of entry to invalidate subsequent references */
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entry->data.next_plus_upper = (ref & ~index_mask) + (index_mask + 1);
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exit:
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write_unlock_bh(&ref_table_lock);
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}
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@ -249,10 +274,13 @@ void *tipc_ref_lock(u32 ref)
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struct reference *r;
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r = &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
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spin_lock_bh(&r->lock);
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if (likely(r->data.reference == ref))
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return r->object;
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spin_unlock_bh(&r->lock);
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if (likely(r->data.reference != 0)) {
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spin_lock_bh(&r->lock);
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if (likely((r->data.reference == ref) && (r->object)))
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return r->object;
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spin_unlock_bh(&r->lock);
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}
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}
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return NULL;
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}
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@ -267,11 +295,12 @@ void tipc_ref_unlock(u32 ref)
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struct reference *r;
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r = &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
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if (likely(r->data.reference == ref))
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if (likely((r->data.reference == ref) && (r->object)))
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spin_unlock_bh(&r->lock);
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else
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err("tipc_ref_unlock() invoked using "
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"obsolete reference\n");
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"invalid reference\n");
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}
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}
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