#ifndef GC_H
#define GC_H
-#include "OSThreads.h"
-
-/* -----------------------------------------------------------------------------
- General scheme
-
- ToDo: move this to the wiki when the implementation is done.
-
- We're only going to try to parallelise the copying GC for now. The
- Plan is as follows.
-
- Each thread has a gc_thread structure (see below) which holds its
- thread-local data. We'll keep a pointer to this in a thread-local
- variable, or possibly in a register.
-
- In the gc_thread structure is a step_workspace for each step. The
- primary purpose of the step_workspace is to hold evacuated objects;
- when an object is evacuated, it is copied to the "todo" block in
- the thread's workspace for the appropriate step. When the todo
- block is full, it is pushed to the global step->todos list, which
- is protected by a lock. (in fact we intervene a one-place buffer
- here to reduce contention).
-
- A thread repeatedly grabs a block of work from one of the
- step->todos lists, scavenges it, and keeps the scavenged block on
- its own ws->scavd_list (this is to avoid unnecessary contention
- returning the completed buffers back to the step: we can just
- collect them all later).
-
- When there is no global work to do, we start scavenging the todo
- blocks in the workspaces. This is where the scan_bd field comes
- in: we can scan the contents of the todo block, when we have
- scavenged the contents of the todo block (up to todo_bd->free), we
- don't want to move this block immediately to the scavd_list,
- because it is probably only partially full. So we remember that we
- have scanned up to this point by saving the block in ws->scan_bd,
- with the current scan pointer in ws->scan. Later, when more
- objects have been copied to this block, we can come back and scan
- the rest. When we visit this workspace again in the future,
- scan_bd may still be the same as todo_bd, or it might be different:
- if enough objects were copied into this block that it filled up,
- then we will have allocated a new todo block, but *not* pushed the
- old one to the step, because it is partially scanned.
-
- The reason to leave scanning the todo blocks until last is that we
- want to deal with full blocks as far as possible.
- ------------------------------------------------------------------------- */
-
-
-/* -----------------------------------------------------------------------------
- Step Workspace
-
- A step workspace exists for each step for each GC thread. The GC
- thread takes a block from the todos list of the step into the
- scanbd and then scans it. Objects referred to by those in the scan
- block are copied into the todo or scavd blocks of the relevant step.
-
- ------------------------------------------------------------------------- */
-
-typedef struct step_workspace_ {
- step * step; // the step for this workspace
- struct gc_thread_ * gct; // the gc_thread that contains this workspace
-
- // where objects to be scavenged go
- bdescr * todo_bd;
- StgPtr todo_free; // free ptr for todo_bd
- StgPtr todo_lim; // lim for todo_bd
-
- bdescr * buffer_todo_bd; // buffer to reduce contention
- // on the step's todos list
-
- // where large objects to be scavenged go
- bdescr * todo_large_objects;
-
- // Objects that have already been, scavenged.
- bdescr * scavd_list;
- nat n_scavd_blocks; // count of blocks in this list
-
- // Partially-full, scavenged, blocks
- bdescr * part_list;
- unsigned int n_part_blocks; // count of above
-
-} step_workspace;
-
-/* ----------------------------------------------------------------------------
- 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
- 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;
-#endif
- nat thread_index; // a zero based index identifying the thread
-
- bdescr * free_blocks; // a buffer of free blocks for this thread
- // during GC without accessing the block
- // allocators spin lock.
-
- StgClosure* static_objects; // live static objects
- StgClosure* scavenged_static_objects; // static objects scavenged so far
-
- lnat gc_count; // number of GCs this thread has done
-
- // block that is currently being scanned
- bdescr * scan_bd;
-
- // --------------------
- // evacuate flags
-
- step *evac_step; // Youngest generation that objects
- // should be evacuated to in
- // evacuate(). (Logically an
- // argument to evacuate, but it's
- // static a lot of the time so we
- // optimise it into a per-thread
- // variable).
-
- rtsBool failed_to_evac; // failure to evacuate an object typically
- // Causes it to be recorded in the mutable
- // object list
-
- rtsBool eager_promotion; // forces promotion to the evac gen
- // instead of the to-space
- // corresponding to the object
-
- lnat thunk_selector_depth; // ummm.... not used as of now
-
-#ifdef USE_PAPI
- int papi_events;
-#endif
-
- // -------------------
- // stats
-
- lnat copied;
- lnat scanned;
- lnat any_work;
- lnat no_work;
- lnat scav_find_work;
-
- // -------------------
- // workspaces
-
- // array of workspaces, indexed by stp->abs_no. This is placed
- // directly at the end of the gc_thread structure so that we can get from
- // the gc_thread pointer to a workspace using only pointer
- // arithmetic, no memory access. This happens in the inner loop
- // of the GC, see Evac.c:alloc_for_copy().
- step_workspace steps[];
-} gc_thread;
-
extern nat N;
extern rtsBool major_gc;
-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
extern bdescr *mark_stack_bdescr;
extern StgPtr *mark_stack;
extern nat mutlist_MUTVARS, mutlist_MUTARRS, mutlist_MVARS, mutlist_OTHERS;
#endif
-StgClosure * isAlive(StgClosure *p);
+extern void markSomeCapabilities (evac_fn evac, void *user, nat i0, nat delta);
+
+#ifdef THREADED_RTS
+extern SpinLock gc_alloc_block_sync;
+#endif
+
+#if defined(PROF_SPIN) && defined(THREADED_RTS)
+StgWord64 whitehole_spin;
+#endif
#define WORK_UNIT_WORDS 128
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