Changeset acf37bc in mainline

Timestamp:

2009-05-15T20:22:26Z (15 years ago)

Author:

Jiri Svoboda <jirik.svoboda@…>

Branches:

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

Children:

687246b

Parents:

40a0e504

Message:

Reduce Udebug overhead with some nifty tricks.

Location:

kernel/generic/src

Files:

• syscall/syscall.c (modified) (2 diffs)
• udebug/udebug.c (modified) (2 diffs)

kernel/generic/src/syscall/syscall.c

@@ -60 +60 @@
 {
         unative_t rc;
+
+#ifdef CONFIG_UDEBUG
+        bool debug;
+
+        /*
+         * Early check for undebugged tasks. We do not lock anything as this
+         * test need not be precise in either way.
+         */
+        debug = THREAD->udebug.active;
         
-#ifdef CONFIG_UDEBUG
-        udebug_syscall_event(a1, a2, a3, a4, a5, a6, id, 0, false);
+        if (debug) {
+                udebug_syscall_event(a1, a2, a3, a4, a5, a6, id, 0, false);
+        }
 #endif
         
@@ -77 +87 @@
         
 #ifdef CONFIG_UDEBUG
-        udebug_syscall_event(a1, a2, a3, a4, a5, a6, id, rc, true);
+        if (debug) {
+                udebug_syscall_event(a1, a2, a3, a4, a5, a6, id, rc, true);
         
-        /*
-         * Stopping point needed for tasks that only invoke non-blocking
-         * system calls.
-         */
-        udebug_stoppable_begin();
-        udebug_stoppable_end();
+                /*
+                 * Stopping point needed for tasks that only invoke
+                 * non-blocking system calls. Not needed if the task
+                 * is not being debugged (it cannot block here).
+                 */
+                udebug_stoppable_begin();
+                udebug_stoppable_end();
+        }
 #endif
         

kernel/generic/src/udebug/udebug.c

@@ -99 +99 @@
 }
 
-/** Do a preliminary check that a debugging session is in progress.
- * 
- * This only requires the THREAD->udebug.lock mutex (and not TASK->udebug.lock
- * mutex). For an undebugged task, this will never block (while there could be
- * collisions by different threads on the TASK mutex), thus improving SMP
- * perormance for undebugged tasks.
- *
- * @return      True if the thread was in a debugging session when the function
- *              checked, false otherwise.
- */
-static bool udebug_thread_precheck(void)
-{
-        bool res;
-
-        mutex_lock(&THREAD->udebug.lock);
-        res = THREAD->udebug.active;
-        mutex_unlock(&THREAD->udebug.lock);
-
-        return res;
-}
-
 /** Start of stoppable section.
  *
@@ -245 +224 @@
 
         etype = end_variant ? UDEBUG_EVENT_SYSCALL_E : UDEBUG_EVENT_SYSCALL_B;
-
-        /* Early check for undebugged tasks */
-        if (!udebug_thread_precheck()) {
-                return;
-        }
 
         mutex_lock(&TASK->udebug.lock);