Changeset 05208d9 in mainline for uspace/lib/c/generic/fibril.c

Timestamp:

2018-07-20T18:33:14Z (6 years ago)

Author:

Jiří Zárevúcky <jiri.zarevucky@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

64ffd83

Parents:

514d561

git-author:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-07-09 19:49:07)

git-committer:

Jiří Zárevúcky <jiri.zarevucky@…> (2018-07-20 18:33:14)

Message:

Single-threaded optimization for ready_semaphore performance.

File:

• uspace/lib/c/generic/fibril.c (modified) (10 diffs)

uspace/lib/c/generic/fibril.c

@@ -54 +54 @@
 
 #define DPRINTF(...) ((void)0)
+#undef READY_DEBUG
 
 /** Member of timeout_list. */
@@ -87 +88 @@
 static futex_t fibril_futex = FUTEX_INITIALIZER;
 static futex_t ready_semaphore = FUTEX_INITIALIZE(0);
+static long ready_st_count;
 
 static LIST_INITIALIZE(ready_list);
@@ -103 +105 @@
 #define _EVENT_TRIGGERED (&_fibril_event_triggered)
 #define _EVENT_TIMED_OUT (&_fibril_event_timed_out)
+
+static inline void _ready_debug_check(void)
+{
+#ifdef READY_DEBUG
+        assert(!multithreaded);
+        long count = (long) list_count(&ready_list) +
+            (long) list_count(&ipc_buffer_free_list);
+        assert(ready_st_count == count);
+#endif
+}
+
+static inline long _ready_count(void)
+{
+        /*
+         * The number of available tokens is always equal to the number
+         * of fibrils in the ready list + the number of free IPC buffer
+         * buckets.
+         */
+
+        if (multithreaded)
+                return atomic_get(&ready_semaphore.val);
+
+        _ready_debug_check();
+        return ready_st_count;
+}
+
+static inline void _ready_up(void)
+{
+        if (multithreaded) {
+                futex_up(&ready_semaphore);
+        } else {
+                ready_st_count++;
+                _ready_debug_check();
+        }
+}
+
+static inline errno_t _ready_down(const struct timeval *expires)
+{
+        if (multithreaded)
+                return futex_down_timeout(&ready_semaphore, expires);
+
+        _ready_debug_check();
+        ready_st_count--;
+        return EOK;
+}
 
 static atomic_t threads_in_ipc_wait = { 0 };
@@ -238 +285 @@
         }
 
-        if (!multithreaded) {
-                /*
-                 * The number of available tokens is always equal to the number
-                 * of fibrils in the ready list + the number of free IPC buffer
-                 * buckets.
-                 */
-
-                assert(atomic_get(&ready_semaphore.val) ==
-                    list_count(&ready_list) + list_count(&ipc_buffer_free_list));
-        }
-
-        errno_t rc = futex_down_timeout(&ready_semaphore, expires);
-
+        errno_t rc = _ready_down(expires);
         if (rc != EOK)
                 return NULL;
@@ -284 +319 @@
         if (rc != EOK && rc != ENOENT) {
                 /* Return token. */
-                futex_up(&ready_semaphore);
+                _ready_up();
                 return NULL;
         }
@@ -316 +351 @@
 
                 /* Return token. */
-                futex_up(&ready_semaphore);
+                _ready_up();
         } else {
                 _ipc_buffer_t *buf = list_pop(&ipc_buffer_free_list, _ipc_buffer_t, link);
@@ -347 +382 @@
         /* Enqueue in ready_list. */
         list_append(&f->link, &ready_list);
-        futex_up(&ready_semaphore);
+        _ready_up();
 
         if (atomic_get(&threads_in_ipc_wait)) {
@@ -370 +405 @@
                 list_append(&buf->link, &ipc_buffer_free_list);
                 /* Return IPC wait token. */
-                futex_up(&ready_semaphore);
+                _ready_up();
 
                 futex_unlock(&ipc_lists_futex);
@@ -754 +789 @@
 int fibril_test_spawn_runners(int n)
 {
-        if (!multithreaded)
+        if (!multithreaded) {
+                _ready_debug_check();
+                atomic_set(&ready_semaphore.val, ready_st_count);
                 multithreaded = true;
+        }
 
         errno_t rc;
@@ -829 +867 @@
         for (int i = 0; i < IPC_BUFFER_COUNT; i++) {
                 list_append(&buffers[i].link, &ipc_buffer_free_list);
-                futex_up(&ready_semaphore);
+                _ready_up();
         }
 }