/* -----------------------------------------------------------------------------
*
- * (c) The GHC Team 1998-2006
+ * (c) The GHC Team 1998-2008
*
* Generational garbage collector
*
bdescr * part_list;
unsigned int n_part_blocks; // count of above
-} step_workspace;
+ StgWord pad[5];
+
+} step_workspace ATTRIBUTE_ALIGNED(64);
+// align so that computing gct->steps[n] is a shift, not a multiply
+// fails if the size is <64, which is why we need the pad above
/* ----------------------------------------------------------------------------
GC thread object
Every GC thread has one of these. It contains all the step specific
- workspaces and other GC thread loacl information. At some later
+ workspaces and other GC thread local information. At some later
point it maybe useful to move this other into the TLS store of the
GC threads
------------------------------------------------------------------------- */
typedef struct gc_thread_ {
#ifdef THREADED_RTS
OSThreadId id; // The OS thread that this struct belongs to
- Mutex wake_mutex;
- Condition wake_cond; // So we can go to sleep between GCs
- rtsBool wakeup;
- rtsBool exit;
+ SpinLock gc_spin;
+ SpinLock mut_spin;
+ volatile rtsBool wakeup;
#endif
nat thread_index; // a zero based index identifying the thread
// block that is currently being scanned
bdescr * scan_bd;
+ // Remembered sets on this CPU. Each GC thread has its own
+ // private per-generation remembered sets, so it can add an item
+ // to the remembered set without taking a lock. The mut_lists
+ // array on a gc_thread is the same as the one on the
+ // corresponding Capability; we stash it here too for easy access
+ // during GC; see recordMutableGen_GC().
+ bdescr ** mut_lists;
+
// --------------------
// evacuate flags
extern nat n_gc_threads;
extern gc_thread **gc_threads;
-register gc_thread *gct __asm__("%rbx");
-// extern gc_thread *gct; // this thread's gct TODO: make thread-local
+
+/* -----------------------------------------------------------------------------
+ The gct variable is thread-local and points to the current thread's
+ gc_thread structure. It is heavily accessed, so we try to put gct
+ into a global register variable if possible; if we don't have a
+ register then use gcc's __thread extension to create a thread-local
+ variable.
+
+ Even on x86 where registers are scarce, it is worthwhile using a
+ register variable here: I measured about a 2-5% slowdown with the
+ __thread version.
+ -------------------------------------------------------------------------- */
+
+#define GLOBAL_REG_DECL(type,name,reg) register type name REG(reg);
+
+#if defined(sparc_HOST_ARCH)
+// Don't use REG_base or R1 for gct on SPARC because they're getting clobbered
+// by something else. Not sure what yet. -- BL 2009/01/03
+
+extern __thread gc_thread* gct;
+#define DECLARE_GCT __thread gc_thread* gct;
+
+#elif defined(REG_Base) && !defined(i386_HOST_ARCH)
+// on i386, REG_Base is %ebx which is also used for PIC, so we don't
+// want to steal it
+
+GLOBAL_REG_DECL(gc_thread*, gct, REG_Base)
+#define DECLARE_GCT /* nothing */
+
+#elif defined(REG_R1)
+
+GLOBAL_REG_DECL(gc_thread*, gct, REG_R1)
+#define DECLARE_GCT /* nothing */
+
+#elif defined(__GNUC__)
+
+extern __thread gc_thread* gct;
+#define DECLARE_GCT __thread gc_thread* gct;
+
+#else
+
+#error Cannot find a way to declare the thread-local gct
+
+#endif
#endif // GCTHREAD_H