Changeset a7504db

Timestamp:

Apr 14, 2021, 4:07:18 PM (4 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

6a9b12b

Parents:

a33c113

Message:

Changed how the cluster idle lock is implemented to be covered by the global RW-lock

Location:

libcfa/src/concurrency

Files:

• kernel/startup.cfa (modified) (2 diffs)
• kernel_private.hfa (modified) (2 diffs)

libcfa/src/concurrency/kernel/startup.cfa

@@ -489 +489 @@
         #endif
 
-        lock( this.cltr->idles );
-                int target = this.cltr->idles.total += 1u;
-        unlock( this.cltr->idles );
-
         // Register and Lock the RWlock so no-one pushes/pops while we are changing the queue
         uint_fast32_t last_size = ready_mutate_register((__processor_id_t*)&this);
+                int target = this.cltr->idles.total += 1u;
 
                 // Adjust the ready queue size
@@ -507 +504 @@
 // Not a ctor, it just preps the destruction but should not destroy members
 static void deinit(processor & this) {
-        lock( this.cltr->idles );
-                int target = this.cltr->idles.total -= 1u;
-        unlock( this.cltr->idles );
-
         // Lock the RWlock so no-one pushes/pops while we are changing the queue
         uint_fast32_t last_size = ready_mutate_lock();
+                int target = this.cltr->idles.total -= 1u;
 
                 // Adjust the ready queue size

libcfa/src/concurrency/kernel_private.hfa

@@ -89 +89 @@
 // Unregister a processor from a given cluster using its id, getting back the original pointer
 void unregister_proc_id( struct __processor_id_t * proc );
-
-//-----------------------------------------------------------------------
-// Cluster idle lock/unlock
-static inline void lock(__cluster_idles & this) {
-        for() {
-                uint64_t l = this.lock;
-                if(
-                        (0 == (l % 2))
-                        && __atomic_compare_exchange_n(&this.lock, &l, l + 1, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)
-                ) return;
-                Pause();
-        }
-}
-
-static inline void unlock(__cluster_idles & this) {
-        /* paranoid */ verify( 1 == (this.lock % 2) );
-        __atomic_fetch_add( &this.lock, 1, __ATOMIC_SEQ_CST );
-}
 
 //=======================================================================
@@ -263 +245 @@
 }
 
+//-----------------------------------------------------------------------
+// Cluster idle lock/unlock
+static inline void lock(__cluster_idles & this) {
+        /* paranoid */ verify( ! __preemption_enabled() );
+
+        // Start by locking the global RWlock so that we know no-one is
+        // adding/removing processors while we mess with the idle lock
+        ready_schedule_lock();
+
+        // Simple counting lock, acquired, acquired by incrementing the counter
+        // to an odd number
+        for() {
+                uint64_t l = this.lock;
+                if(
+                        (0 == (l % 2))
+                        && __atomic_compare_exchange_n(&this.lock, &l, l + 1, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)
+                ) return;
+                Pause();
+        }
+
+        /* paranoid */ verify( ! __preemption_enabled() );
+}
+
+static inline void unlock(__cluster_idles & this) {
+        /* paranoid */ verify( ! __preemption_enabled() );
+
+        /* paranoid */ verify( 1 == (this.lock % 2) );
+        // Simple couting lock, release by incrementing to an even number
+        __atomic_fetch_add( &this.lock, 1, __ATOMIC_SEQ_CST );
+
+        // Release the global lock, which we acquired when locking
+        ready_schedule_unlock();
+
+        /* paranoid */ verify( ! __preemption_enabled() );
+}
+
 //=======================================================================
 // Ready-Queue API