X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fovs-thread.c;h=4dfccaf3e5f8aae2d323615e28e33aa7236626e3;hb=6b59b543;hp=e9366e2ded012da0f398cc2141403e7c1ce0b544;hpb=834d6cafe4797861b7547966b4dcc95b374331be;p=sliver-openvswitch.git

diff --git a/lib/ovs-thread.c b/lib/ovs-thread.c
index e9366e2de..4dfccaf3e 100644
--- a/lib/ovs-thread.c
+++ b/lib/ovs-thread.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013 Nicira, Inc.
+ * Copyright (c) 2013, 2014 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include "compiler.h"
+#include "hash.h"
 #include "poll-loop.h"
 #include "socket-util.h"
 #include "util.h"
@@ -47,6 +48,7 @@ static bool multithreaded;
     void \
     ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
                             const char *where) \
+        OVS_NO_THREAD_SAFETY_ANALYSIS \
     { \
         struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
         int error = pthread_##TYPE##_##FUN(&l->lock); \
@@ -63,6 +65,7 @@ LOCK_FUNCTION(rwlock, wrlock);
     int \
     ovs_##TYPE##_##FUN##_at(const struct ovs_##TYPE *l_, \
                             const char *where) \
+        OVS_NO_THREAD_SAFETY_ANALYSIS \
     { \
         struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
         int error = pthread_##TYPE##_##FUN(&l->lock); \
@@ -81,6 +84,7 @@ TRY_LOCK_FUNCTION(rwlock, trywrlock);
 #define UNLOCK_FUNCTION(TYPE, FUN) \
     void \
     ovs_##TYPE##_##FUN(const struct ovs_##TYPE *l_) \
+        OVS_NO_THREAD_SAFETY_ANALYSIS \
     { \
         struct ovs_##TYPE *l = CONST_CAST(struct ovs_##TYPE *, l_); \
         int error; \
@@ -121,6 +125,12 @@ XPTHREAD_FUNC1(pthread_mutexattr_destroy, pthread_mutexattr_t *);
 XPTHREAD_FUNC2(pthread_mutexattr_settype, pthread_mutexattr_t *, int);
 XPTHREAD_FUNC2(pthread_mutexattr_gettype, pthread_mutexattr_t *, int *);
 
+XPTHREAD_FUNC1(pthread_rwlockattr_init, pthread_rwlockattr_t *);
+XPTHREAD_FUNC1(pthread_rwlockattr_destroy, pthread_rwlockattr_t *);
+#ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
+XPTHREAD_FUNC2(pthread_rwlockattr_setkind_np, pthread_rwlockattr_t *, int);
+#endif
+
 XPTHREAD_FUNC2(pthread_cond_init, pthread_cond_t *, pthread_condattr_t *);
 XPTHREAD_FUNC1(pthread_cond_destroy, pthread_cond_t *);
 XPTHREAD_FUNC1(pthread_cond_signal, pthread_cond_t *);
@@ -130,6 +140,7 @@ XPTHREAD_FUNC2(pthread_join, pthread_t, void **);
 
 typedef void destructor_func(void *);
 XPTHREAD_FUNC2(pthread_key_create, pthread_key_t *, destructor_func *);
+XPTHREAD_FUNC1(pthread_key_delete, pthread_key_t);
 XPTHREAD_FUNC2(pthread_setspecific, pthread_key_t, const void *);
 
 static void
@@ -163,17 +174,36 @@ ovs_mutex_init_recursive(const struct ovs_mutex *mutex)
     ovs_mutex_init__(mutex, PTHREAD_MUTEX_RECURSIVE);
 }
 
+/* Initializes 'mutex' as a recursive mutex. */
+void
+ovs_mutex_init_adaptive(const struct ovs_mutex *mutex)
+{
+#ifdef PTHREAD_ADAPTIVE_MUTEX_INITIALIZER_NP
+    ovs_mutex_init__(mutex, PTHREAD_MUTEX_ADAPTIVE_NP);
+#else
+    ovs_mutex_init(mutex);
+#endif
+}
+
 void
 ovs_rwlock_init(const struct ovs_rwlock *l_)
 {
     struct ovs_rwlock *l = CONST_CAST(struct ovs_rwlock *, l_);
+    pthread_rwlockattr_t attr;
     int error;
 
     l->where = NULL;
+
+    xpthread_rwlockattr_init(&attr);
+#ifdef PTHREAD_RWLOCK_WRITER_NONRECURSIVE_INITIALIZER_NP
+    xpthread_rwlockattr_setkind_np(
+        &attr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+#endif
     error = pthread_rwlock_init(&l->lock, NULL);
     if (OVS_UNLIKELY(error)) {
         ovs_abort(error, "pthread_rwlock_init failed");
     }
+    xpthread_rwlockattr_destroy(&attr);
 }
 
 void
@@ -306,4 +336,350 @@ may_fork(void)
 {
     return !must_not_fork;
 }
+
+/* ovsthread_counter.
+ *
+ * We implement the counter as an array of N_COUNTERS individual counters, each
+ * with its own lock.  Each thread uses one of the counters chosen based on a
+ * hash of the thread's ID, the idea being that, statistically, different
+ * threads will tend to use different counters and therefore avoid
+ * interfering with each other.
+ *
+ * Undoubtedly, better implementations are possible. */
+
+/* Basic counter structure. */
+struct ovsthread_counter__ {
+    struct ovs_mutex mutex;
+    unsigned long long int value;
+};
+
+/* Pad the basic counter structure to 64 bytes to avoid cache line
+ * interference. */
+struct ovsthread_counter {
+    struct ovsthread_counter__ c;
+    char pad[ROUND_UP(sizeof(struct ovsthread_counter__), 64)
+             - sizeof(struct ovsthread_counter__)];
+};
+
+#define N_COUNTERS 16
+
+struct ovsthread_counter *
+ovsthread_counter_create(void)
+{
+    struct ovsthread_counter *c;
+    int i;
+
+    c = xmalloc(N_COUNTERS * sizeof *c);
+    for (i = 0; i < N_COUNTERS; i++) {
+        ovs_mutex_init(&c[i].c.mutex);
+        c[i].c.value = 0;
+    }
+    return c;
+}
+
+void
+ovsthread_counter_destroy(struct ovsthread_counter *c)
+{
+    if (c) {
+        int i;
+
+        for (i = 0; i < N_COUNTERS; i++) {
+            ovs_mutex_destroy(&c[i].c.mutex);
+        }
+        free(c);
+    }
+}
+
+void
+ovsthread_counter_inc(struct ovsthread_counter *c, unsigned long long int n)
+{
+    c = &c[hash_int(ovsthread_id_self(), 0) % N_COUNTERS];
+
+    ovs_mutex_lock(&c->c.mutex);
+    c->c.value += n;
+    ovs_mutex_unlock(&c->c.mutex);
+}
+
+unsigned long long int
+ovsthread_counter_read(const struct ovsthread_counter *c)
+{
+    unsigned long long int sum;
+    int i;
+
+    sum = 0;
+    for (i = 0; i < N_COUNTERS; i++) {
+        ovs_mutex_lock(&c[i].c.mutex);
+        sum += c[i].c.value;
+        ovs_mutex_unlock(&c[i].c.mutex);
+    }
+    return sum;
+}
+
+/* Parses /proc/cpuinfo for the total number of physical cores on this system
+ * across all CPU packages, not counting hyper-threads.
+ *
+ * Sets *n_cores to the total number of cores on this system, or 0 if the
+ * number cannot be determined. */
+static void
+parse_cpuinfo(long int *n_cores)
+{
+    static const char file_name[] = "/proc/cpuinfo";
+    char line[128];
+    uint64_t cpu = 0; /* Support up to 64 CPU packages on a single system. */
+    long int cores = 0;
+    FILE *stream;
+
+    stream = fopen(file_name, "r");
+    if (!stream) {
+        VLOG_DBG("%s: open failed (%s)", file_name, ovs_strerror(errno));
+        return;
+    }
+
+    while (fgets(line, sizeof line, stream)) {
+        unsigned int id;
+
+        /* Find the next CPU package. */
+        if (ovs_scan(line, "physical id%*[^:]: %u", &id)) {
+            if (id > 63) {
+                VLOG_WARN("Counted over 64 CPU packages on this system. "
+                          "Parsing %s for core count may be inaccurate.",
+                          file_name);
+                cores = 0;
+                break;
+            }
+
+            if (cpu & (1 << id)) {
+                /* We've already counted this package's cores. */
+                continue;
+            }
+            cpu |= 1 << id;
+
+            /* Find the number of cores for this package. */
+            while (fgets(line, sizeof line, stream)) {
+                int count;
+
+                if (ovs_scan(line, "cpu cores%*[^:]: %u", &count)) {
+                    cores += count;
+                    break;
+                }
+            }
+        }
+    }
+    fclose(stream);
+
+    *n_cores = cores;
+}
+
+/* Returns the total number of cores on this system, or 0 if the number cannot
+ * be determined.
+ *
+ * Tries not to count hyper-threads, but may be inaccurate - particularly on
+ * platforms that do not provide /proc/cpuinfo, but also if /proc/cpuinfo is
+ * formatted different to the layout that parse_cpuinfo() expects. */
+int
+count_cpu_cores(void)
+{
+    static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
+    static long int n_cores;
+
+    if (ovsthread_once_start(&once)) {
+        parse_cpuinfo(&n_cores);
+        if (!n_cores) {
+            n_cores = sysconf(_SC_NPROCESSORS_ONLN);
+        }
+        ovsthread_once_done(&once);
+    }
+
+    return n_cores > 0 ? n_cores : 0;
+}
+
+/* ovsthread_key. */
+
+#define L1_SIZE 1024
+#define L2_SIZE 1024
+#define MAX_KEYS (L1_SIZE * L2_SIZE)
+
+/* A piece of thread-specific data. */
+struct ovsthread_key {
+    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;
+};
+
+/* Per-thread data structure. */
+struct ovsthread_key_slots {
+    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);
+
+static void *
+clear_slot(struct ovsthread_key_slots *slots, unsigned int index)
+{
+    void **p2 = slots->p1[index / L2_SIZE];
+    if (p2) {
+        void **valuep = &p2[index % L2_SIZE];
+        void *value = *valuep;
+        *valuep = NULL;
+        return value;
+    } else {
+        return NULL;
+    }
+}
+
+static void
+ovsthread_key_destruct__(void *slots_)
+{
+    struct ovsthread_key_slots *slots = slots_;
+    struct ovsthread_key *key;
+    unsigned int n;
+    int i;
+
+    ovs_mutex_lock(&key_mutex);
+    list_remove(&slots->list_node);
+    LIST_FOR_EACH (key, list_node, &inuse_keys) {
+        void *value = clear_slot(slots, key->index);
+        if (value && key->destructor) {
+            key->destructor(value);
+        }
+    }
+    n = n_keys;
+    ovs_mutex_unlock(&key_mutex);
+
+    for (i = 0; i < n / L2_SIZE; i++) {
+        free(slots->p1[i]);
+    }
+    free(slots);
+}
+
+/* Initializes '*keyp' as a thread-specific data key.  The data items are
+ * initially null in all threads.
+ *
+ * If a thread exits with non-null data, then 'destructor', if nonnull, will be
+ * called passing the final data value as its argument.  'destructor' must not
+ * call any thread-specific data functions in this API.
+ *
+ * This function is similar to xpthread_key_create(). */
+void
+ovsthread_key_create(ovsthread_key_t *keyp, void (*destructor)(void *))
+{
+    static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
+    struct ovsthread_key *key;
+
+    if (ovsthread_once_start(&once)) {
+        xpthread_key_create(&tsd_key, ovsthread_key_destruct__);
+        ovsthread_once_done(&once);
+    }
+
+    ovs_mutex_lock(&key_mutex);
+    if (list_is_empty(&free_keys)) {
+        key = xmalloc(sizeof *key);
+        key->index = n_keys++;
+        if (key->index >= MAX_KEYS) {
+            abort();
+        }
+    } else {
+        key = CONTAINER_OF(list_pop_back(&free_keys),
+                            struct ovsthread_key, list_node);
+    }
+    list_push_back(&inuse_keys, &key->list_node);
+    key->destructor = destructor;
+    ovs_mutex_unlock(&key_mutex);
+
+    *keyp = key;
+}
+
+/* Frees 'key'.  The destructor supplied to ovsthread_key_create(), if any, is
+ * not called.
+ *
+ * This function is similar to xpthread_key_delete(). */
+void
+ovsthread_key_delete(ovsthread_key_t key)
+{
+    struct ovsthread_key_slots *slots;
+
+    ovs_mutex_lock(&key_mutex);
+
+    /* Move 'key' from 'inuse_keys' to 'free_keys'. */
+    list_remove(&key->list_node);
+    list_push_back(&free_keys, &key->list_node);
+
+    /* Clear this slot in all threads. */
+    LIST_FOR_EACH (slots, list_node, &slots_list) {
+        clear_slot(slots, key->index);
+    }
+
+    ovs_mutex_unlock(&key_mutex);
+}
+
+static void **
+ovsthread_key_lookup__(const struct ovsthread_key *key)
+{
+    struct ovsthread_key_slots *slots;
+    void **p2;
+
+    slots = pthread_getspecific(tsd_key);
+    if (!slots) {
+        slots = xzalloc(sizeof *slots);
+
+        ovs_mutex_lock(&key_mutex);
+        pthread_setspecific(tsd_key, slots);
+        list_push_back(&slots_list, &slots->list_node);
+        ovs_mutex_unlock(&key_mutex);
+    }
+
+    p2 = slots->p1[key->index / L2_SIZE];
+    if (!p2) {
+        p2 = xzalloc(L2_SIZE * sizeof *p2);
+        slots->p1[key->index / L2_SIZE] = p2;
+    }
+
+    return &p2[key->index % L2_SIZE];
+}
+
+/* Sets the value of thread-specific data item 'key', in the current thread, to
+ * 'value'.
+ *
+ * This function is similar to pthread_setspecific(). */
+void
+ovsthread_setspecific(ovsthread_key_t key, const void *value)
+{
+    *ovsthread_key_lookup__(key) = CONST_CAST(void *, value);
+}
+
+/* Returns the value of thread-specific data item 'key' in the current thread.
+ *
+ * This function is similar to pthread_getspecific(). */
+void *
+ovsthread_getspecific(ovsthread_key_t key)
+{
+    return *ovsthread_key_lookup__(key);
+}
 #endif