score: Introduce Thread_queue_Heads

Move the storage for the thread queue heads to the threads.  Each thread
provides a set of thread queue heads allocated from a dedicated memory
pool.  In case a thread blocks on a queue, then it lends its heads to
the queue.  In case the thread unblocks, then it takes a free set of
threads from the queue.  Since a thread can block on at most one queue
this works.  This mechanism is used in FreeBSD.  The motivation for this
change is to reduce the memory demands of the synchronization objects.
On a 32-bit uni-processor configuration the Thread_queue_Control size is
now 8 bytes, compared to 64 bytes in RTEMS 4.10 (other changes reduced
the size as well).

1 files changed, 25 insertions, 22 deletions

diff --git a/cpukit/posix/src/killinfo.c b/cpukit/posix/src/killinfo.c
index d08e68684b..a90f4b1221 100644
--- a/cpukit/posix/src/killinfo.c
+++ b/cpukit/posix/src/killinfo.c
@@ -70,11 +70,11 @@ int killinfo(
   Thread_Control              *the_thread;
   Thread_Control              *interested;
   Priority_Control             interested_priority;
-  Chain_Control               *the_chain;
   Chain_Node                  *the_node;
   siginfo_t                    siginfo_struct;
   siginfo_t                   *siginfo;
   POSIX_signals_Siginfo_node  *psiginfo;
+  Thread_queue_Heads          *heads;
 
   /*
    *  Only supported for the "calling process" (i.e. this node).
@@ -140,32 +140,35 @@ int killinfo(
 
   /* XXX violation of visibility -- need to define thread queue support */
 
-  the_chain = &_POSIX_signals_Wait_queue.Queue.Heads.Fifo;
+  heads = _POSIX_signals_Wait_queue.Queue.heads;
+  if ( heads != NULL ) {
+    Chain_Control *the_chain = &heads->Heads.Fifo;
 
-  for ( the_node = _Chain_First( the_chain );
-        !_Chain_Is_tail( the_chain, the_node ) ;
-        the_node = the_node->next ) {
+    for ( the_node = _Chain_First( the_chain );
+          !_Chain_Is_tail( the_chain, the_node ) ;
+          the_node = the_node->next ) {
 
-    the_thread = THREAD_CHAIN_NODE_TO_THREAD( the_node );
-    api = the_thread->API_Extensions[ THREAD_API_POSIX ];
+      the_thread = THREAD_CHAIN_NODE_TO_THREAD( the_node );
+      api = the_thread->API_Extensions[ THREAD_API_POSIX ];
 
-    #if defined(DEBUG_SIGNAL_PROCESSING)
-      printk( "Waiting Thread=%p option=0x%08x mask=0x%08x blocked=0x%08x\n",
-        the_thread, the_thread->Wait.option, mask, api->signals_blocked);
-    #endif
+      #if defined(DEBUG_SIGNAL_PROCESSING)
+        printk( "Waiting Thread=%p option=0x%08x mask=0x%08x blocked=0x%08x\n",
+          the_thread, the_thread->Wait.option, mask, api->signals_blocked);
+      #endif
 
-    /*
-     * Is this thread is actually blocked waiting for the signal?
-     */
-    if (the_thread->Wait.option & mask)
-      goto process_it;
+      /*
+       * Is this thread is actually blocked waiting for the signal?
+       */
+      if (the_thread->Wait.option & mask)
+        goto process_it;
 
-    /*
-     * Is this thread is blocked waiting for another signal but has
-     * not blocked this one?
-     */
-    if (~api->signals_blocked & mask)
-      goto process_it;
+      /*
+       * Is this thread is blocked waiting for another signal but has
+       * not blocked this one?
+       */
+      if (~api->signals_blocked & mask)
+        goto process_it;
+    }
   }
 
   /*