*
* Capabilities
*
- * The notion of a capability is used when operating in multi-threaded
- * environments (which the THREADED_RTS build of the RTS does), to
- * hold all the state an OS thread/task needs to run Haskell code:
- * its STG registers, a pointer to its TSO, a nursery etc. During
- * STG execution, a pointer to the capabilitity is kept in a
- * register (BaseReg).
+ * A Capability holds all the state an OS thread/task needs to run
+ * Haskell code: its STG registers, a pointer to its TSO, a nursery
+ * etc. During STG execution, a pointer to the Capabilitity is kept in
+ * a register (BaseReg).
*
- * Only in an THREADED_RTS build will there be multiple capabilities,
- * in the non-threaded builds there is one global capability, namely
+ * Only in a THREADED_RTS build will there be multiple capabilities,
+ * in the non-threaded RTS there is one global capability, called
* MainCapability.
*
- * This header file contains the functions for working with capabilities.
- * (the main, and only, consumer of this interface is the scheduler).
- *
* --------------------------------------------------------------------------*/
#ifndef CAPABILITY_H
#define CAPABILITY_H
-#include "RtsFlags.h"
+#include "sm/GC.h" // for evac_fn
#include "Task.h"
#include "Sparks.h"
+BEGIN_RTS_PRIVATE
+
struct Capability_ {
// State required by the STG virtual machine when running Haskell
// code. During STG execution, the BaseReg register always points
// catching unsafe call-ins.
rtsBool in_haskell;
+ // true if this Capability is currently in the GC
+ rtsBool in_gc;
+
// The run queue. The Task owning this Capability has exclusive
// access to its run queue, so can wake up threads without
// taking a lock, and the common path through the scheduler is
Task *suspended_ccalling_tasks;
// One mutable list per generation, so we don't need to take any
- // locks when updating an old-generation thunk. These
- // mini-mut-lists are moved onto the respective gen->mut_list at
- // each GC.
+ // locks when updating an old-generation thunk. This also lets us
+ // keep track of which closures this CPU has been mutating, so we
+ // can traverse them using the right thread during GC and avoid
+ // unnecessarily moving the data from one cache to another.
bdescr **mut_lists;
+ bdescr **saved_mut_lists; // tmp use during GC
+
+ // block for allocating pinned objects into
+ bdescr *pinned_object_block;
// Context switch flag. We used to have one global flag, now one
// per capability. Locks required : none (conflicts are harmless)
} // typedef Capability is defined in RtsAPI.h
// Capabilities are stored in an array, so make sure that adjacent
// Capabilities don't share any cache-lines:
- ATTRIBUTE_ALIGNED(64);
+#ifndef mingw32_HOST_OS
+ ATTRIBUTE_ALIGNED(64)
+#endif
+ ;
#if defined(THREADED_RTS)
INLINE_HEADER Capability *
regTableToCapability (StgRegTable *reg)
{
- return (Capability *)((void *)((unsigned char*)reg - sizeof(StgFunTable)));
+ return (Capability *)((void *)((unsigned char*)reg - STG_FIELD_OFFSET(Capability,r)));
}
// Initialise the available capabilities.
rtsBool always_wakeup STG_UNUSED) {};
#endif
-#if !IN_STG_CODE
-// one global capability
-extern Capability MainCapability;
-#endif
+// declared in includes/rts/Threads.h:
+// extern Capability MainCapability;
+
+// declared in includes/rts/Threads.h:
+// extern nat n_capabilities;
// Array of all the capabilities
//
-extern nat n_capabilities;
extern Capability *capabilities;
// The Capability that was last free. Used as a good guess for where
extern Capability *last_free_capability;
// GC indicator, in scope for the scheduler
+#define PENDING_GC_SEQ 1
+#define PENDING_GC_PAR 2
extern volatile StgWord waiting_for_gc;
// Acquires a capability at a return point. If *cap is non-NULL, then
// need to service some global event.
//
void prodOneCapability (void);
+void prodCapability (Capability *cap, Task *task);
// Similar to prodOneCapability(), but prods all of them.
//
//
rtsBool tryGrabCapability (Capability *cap, Task *task);
-// Try to steal a spark from other Capabilities
+// Try to find a spark to run
//
-StgClosure *stealWork (Capability *cap);
+StgClosure *findSpark (Capability *cap);
// True if any capabilities have sparks
//
// cause all capabilities to context switch as soon as possible.
void setContextSwitches(void);
+INLINE_HEADER void contextSwitchCapability(Capability *cap);
// Free all capabilities
void freeCapabilities (void);
-// FOr the GC:
+// For the GC:
void markSomeCapabilities (evac_fn evac, void *user, nat i0, nat delta,
rtsBool prune_sparks);
void markCapabilities (evac_fn evac, void *user);
{ return discardSparks(cap->sparks); }
#endif
+INLINE_HEADER void
+contextSwitchCapability (Capability *cap)
+{
+ // setting HpLim to NULL ensures that the next heap check will
+ // fail, and the thread will return to the scheduler.
+ cap->r.rHpLim = NULL;
+ // But just in case it didn't work (the target thread might be
+ // modifying HpLim at the same time), we set the end-of-block
+ // context-switch flag too:
+ cap->context_switch = 1;
+}
+
+END_RTS_PRIVATE
+
#endif /* CAPABILITY_H */
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