On Mon, Jan 13, 2014 at 03:24:28PM -0800, Ethan Jackson wrote:
> As discussed off list I'd like a comment explaining why we need the
> free list. Other than that:
>
> Acked-by: Ethan Jackson <et...@nicira.com>
Thanks. I added that and several other comments.
diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c
index 6e6af98..f532070 100644
--- a/lib/ovs-thread.c
+++ b/lib/ovs-thread.c
@@ -475,27 +475,44 @@ count_cpu_cores(void)
#define L2_SIZE 1024
#define MAX_KEYS (L1_SIZE * L2_SIZE)
+/* A piece of thread-specific data. */
struct ovsthread_key {
- struct list list_node;
+ struct list list_node; /* In 'inuse_keys' or 'free_keys'. */
+ void (*destructor)(void *); /* Called at thread exit. */
+
+ /* Indexes into the per-thread array in struct ovsthread_key_slots.
+ * This key's data is stored in p1[index / L2_SIZE][index % L2_SIZE]. */
unsigned int index;
- void (*destructor)(void *);
};
+/* Per-thread data structure. */
struct ovsthread_key_slots {
- struct list list_node;
+ struct list list_node; /* In 'slots_list'. */
void **p1[L1_SIZE];
};
+/* Contains "struct ovsthread_key_slots *". */
static pthread_key_t tsd_key;
+/* Guards data structures below. */
static struct ovs_mutex key_mutex = OVS_MUTEX_INITIALIZER;
+/* 'inuse_keys' holds "struct ovsthread_key"s that have been created and not
+ * yet destroyed.
+ *
+ * 'free_keys' holds "struct ovsthread_key"s that have been deleted and are
+ * ready for reuse. (We keep them around only to be able to easily locate
+ * free indexes.)
+ *
+ * Together, 'inuse_keys' and 'free_keys' hold an ovsthread_key for every index
+ * from 0 to n_keys - 1, inclusive. */
static struct list inuse_keys OVS_GUARDED_BY(key_mutex)
= LIST_INITIALIZER(&inuse_keys);
static struct list free_keys OVS_GUARDED_BY(key_mutex)
= LIST_INITIALIZER(&free_keys);
static unsigned int n_keys OVS_GUARDED_BY(key_mutex);
+/* All existing struct ovsthread_key_slots. */
static struct list slots_list OVS_GUARDED_BY(key_mutex)
= LIST_INITIALIZER(&slots_list);
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