/* Sleep delay in ms */
#define RCU_SLEEP_DELAY_MS 10
-#define INIT_NR_THREADS 8
-#define ARENA_INIT_ALLOC \
- sizeof(struct registry_chunk) \
- + INIT_NR_THREADS * sizeof(struct lttng_ust_urcu_reader)
+#define INIT_READER_COUNT 8
/*
* Active attempts to check for reader Q.S. before calling sleep().
static CDS_LIST_HEAD(registry);
struct registry_chunk {
- size_t data_len; /* data length */
- size_t used; /* amount of data used */
+ size_t capacity; /* capacity of this chunk (in elements) */
+ size_t used; /* count of elements used */
struct cds_list_head node; /* chunk_list node */
- char data[];
+ struct lttng_ust_urcu_reader readers[];
};
struct registry_arena {
}
}
+/* Get the size of a chunk's allocation from its capacity (an element count). */
+static size_t chunk_allocation_size(size_t capacity)
+{
+ return (capacity * sizeof(struct lttng_ust_urcu_reader)) +
+ sizeof(struct registry_chunk);
+}
+
/*
* Always called with rcu_registry lock held. Releases this lock between
* iterations and grabs it again. Holds the lock when it returns.
void expand_arena(struct registry_arena *arena)
{
struct registry_chunk *new_chunk, *last_chunk;
- size_t old_chunk_len, new_chunk_len;
+ size_t old_chunk_size_bytes, new_chunk_size_bytes, new_capacity;
/* No chunk. */
if (cds_list_empty(&arena->chunk_list)) {
- assert(ARENA_INIT_ALLOC >=
- sizeof(struct registry_chunk)
- + sizeof(struct lttng_ust_urcu_reader));
- new_chunk_len = ARENA_INIT_ALLOC;
+ new_chunk_size_bytes = chunk_allocation_size(INIT_READER_COUNT);
new_chunk = (struct registry_chunk *) mmap(NULL,
- new_chunk_len,
+ new_chunk_size_bytes,
PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE,
-1, 0);
if (new_chunk == MAP_FAILED)
abort();
- memset(new_chunk, 0, new_chunk_len);
- new_chunk->data_len =
- new_chunk_len - sizeof(struct registry_chunk);
+ memset(new_chunk, 0, new_chunk_size_bytes);
+ new_chunk->capacity = INIT_READER_COUNT;
cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
return; /* We're done. */
}
/* Try expanding last chunk. */
last_chunk = cds_list_entry(arena->chunk_list.prev,
struct registry_chunk, node);
- old_chunk_len =
- last_chunk->data_len + sizeof(struct registry_chunk);
- new_chunk_len = old_chunk_len << 1;
+ old_chunk_size_bytes = chunk_allocation_size(last_chunk->capacity);
+ new_capacity = last_chunk->capacity << 1;
+ new_chunk_size_bytes = chunk_allocation_size(new_capacity);
- /* Don't allow memory mapping to move, just expand. */
- new_chunk = mremap_wrapper(last_chunk, old_chunk_len,
- new_chunk_len, 0);
+ /* Don't allow memory mapping to move, just expand. */
+ new_chunk = mremap_wrapper(last_chunk, old_chunk_size_bytes,
+ new_chunk_size_bytes, 0);
if (new_chunk != MAP_FAILED) {
/* Should not have moved. */
assert(new_chunk == last_chunk);
- memset((char *) last_chunk + old_chunk_len, 0,
- new_chunk_len - old_chunk_len);
- last_chunk->data_len =
- new_chunk_len - sizeof(struct registry_chunk);
+ memset((char *) last_chunk + old_chunk_size_bytes, 0,
+ new_chunk_size_bytes - old_chunk_size_bytes);
+ last_chunk->capacity = new_capacity;
return; /* We're done. */
}
/* Remap did not succeed, we need to add a new chunk. */
new_chunk = (struct registry_chunk *) mmap(NULL,
- new_chunk_len,
+ new_chunk_size_bytes,
PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE,
-1, 0);
if (new_chunk == MAP_FAILED)
abort();
- memset(new_chunk, 0, new_chunk_len);
- new_chunk->data_len =
- new_chunk_len - sizeof(struct registry_chunk);
+ memset(new_chunk, 0, new_chunk_size_bytes);
+ new_chunk->capacity = new_capacity;
cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
}
struct lttng_ust_urcu_reader *arena_alloc(struct registry_arena *arena)
{
struct registry_chunk *chunk;
- struct lttng_ust_urcu_reader *rcu_reader_reg;
int expand_done = 0; /* Only allow to expand once per alloc */
- size_t len = sizeof(struct lttng_ust_urcu_reader);
retry:
cds_list_for_each_entry(chunk, &arena->chunk_list, node) {
- if (chunk->data_len - chunk->used < len)
+ size_t spot_idx;
+
+ /* Skip fully used chunks. */
+ if (chunk->used == chunk->capacity) {
continue;
- /* Find spot */
- for (rcu_reader_reg = (struct lttng_ust_urcu_reader *) &chunk->data[0];
- rcu_reader_reg < (struct lttng_ust_urcu_reader *) &chunk->data[chunk->data_len];
- rcu_reader_reg++) {
- if (!rcu_reader_reg->alloc) {
- rcu_reader_reg->alloc = 1;
- chunk->used += len;
- return rcu_reader_reg;
+ }
+
+ /* Find a spot. */
+ for (spot_idx = 0; spot_idx < chunk->capacity; spot_idx++) {
+ if (!chunk->readers[spot_idx].alloc) {
+ chunk->readers[spot_idx].alloc = 1;
+ chunk->used++;
+ return &chunk->readers[spot_idx];
}
}
}
cds_list_del(&rcu_reader_reg->node);
rcu_reader_reg->tid = 0;
rcu_reader_reg->alloc = 0;
- chunk->used -= sizeof(struct lttng_ust_urcu_reader);
+ chunk->used--;
}
static
struct registry_chunk *chunk;
cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) {
- if (rcu_reader_reg < (struct lttng_ust_urcu_reader *) &chunk->data[0])
+ if (rcu_reader_reg < (struct lttng_ust_urcu_reader *) &chunk->readers[0])
continue;
- if (rcu_reader_reg >= (struct lttng_ust_urcu_reader *) &chunk->data[chunk->data_len])
+ if (rcu_reader_reg >= (struct lttng_ust_urcu_reader *) &chunk->readers[chunk->capacity])
continue;
return chunk;
}
cds_list_for_each_entry_safe(chunk, tmp,
®istry_arena.chunk_list, node) {
- munmap((void *) chunk, chunk->data_len
- + sizeof(struct registry_chunk));
+ munmap((void *) chunk, chunk_allocation_size(chunk->capacity));
}
CDS_INIT_LIST_HEAD(®istry_arena.chunk_list);
ret = pthread_key_delete(lttng_ust_urcu_key);
void lttng_ust_urcu_prune_registry(void)
{
struct registry_chunk *chunk;
- struct lttng_ust_urcu_reader *rcu_reader_reg;
cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) {
- for (rcu_reader_reg = (struct lttng_ust_urcu_reader *) &chunk->data[0];
- rcu_reader_reg < (struct lttng_ust_urcu_reader *) &chunk->data[chunk->data_len];
- rcu_reader_reg++) {
- if (!rcu_reader_reg->alloc)
+ size_t spot_idx;
+
+ for (spot_idx = 0; spot_idx < chunk->capacity; spot_idx++) {
+ struct lttng_ust_urcu_reader *reader = &chunk->readers[spot_idx];
+
+ if (!reader->alloc)
continue;
- if (rcu_reader_reg->tid == pthread_self())
+ if (reader->tid == pthread_self())
continue;
- cleanup_thread(chunk, rcu_reader_reg);
+ cleanup_thread(chunk, reader);
}
}
}
projects / lttng-ust.git / blobdiff