diff options
Diffstat (limited to '')
| -rw-r--r-- | gc/linux_threads.c | 1256 |
1 files changed, 1143 insertions, 113 deletions
diff --git a/gc/linux_threads.c b/gc/linux_threads.c index 8287dce..074be89 100644 --- a/gc/linux_threads.c +++ b/gc/linux_threads.c @@ -2,6 +2,7 @@ * Copyright (c) 1994 by Xerox Corporation. All rights reserved. * Copyright (c) 1996 by Silicon Graphics. All rights reserved. * Copyright (c) 1998 by Fergus Henderson. All rights reserved. + * Copyright (c) 2000-2001 by Hewlett-Packard Company. All rights reserved. * * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED * OR IMPLIED. ANY USE IS AT YOUR OWN RISK. @@ -17,35 +18,96 @@ * thread package for Linux which is included in libc6. * * This code relies on implementation details of LinuxThreads, - * (i.e. properties not guaranteed by the Pthread standard): - * - * - the function GC_linux_thread_top_of_stack(void) - * relies on the way LinuxThreads lays out thread stacks - * in the address space. + * (i.e. properties not guaranteed by the Pthread standard), + * though this version now does less of that than the other Pthreads + * support code. * * Note that there is a lot of code duplication between linux_threads.c - * and irix_threads.c; any changes made here may need to be reflected - * there too. + * and thread support for some of the other Posix platforms; any changes + * made here may need to be reflected there too. + */ +/* + * Linux_threads.c now also includes some code to support HPUX and + * OSF1 (Compaq Tru64 Unix, really). The OSF1 support is not yet + * functional. The OSF1 code is based on Eric Benson's + * patch, though that was originally against hpux_irix_threads. The code + * here is completely untested. With 0.0000001% probability, it might + * actually work. + * + * Eric also suggested an alternate basis for a lock implementation in + * his code: + * + #elif defined(OSF1) + * + unsigned long GC_allocate_lock = 0; + * + msemaphore GC_allocate_semaphore; + * + # define GC_TRY_LOCK() \ + * + ((msem_lock(&GC_allocate_semaphore, MSEM_IF_NOWAIT) == 0) \ + * + ? (GC_allocate_lock = 1) \ + * + : 0) + * + # define GC_LOCK_TAKEN GC_allocate_lock */ /* #define DEBUG_THREADS 1 */ /* ANSI C requires that a compilation unit contains something */ -# include "gc_priv.h" -# if defined(LINUX_THREADS) +# if defined(GC_LINUX_THREADS) || defined(LINUX_THREADS) \ + || defined(GC_HPUX_THREADS) || defined(HPUX_THREADS) \ + || defined(GC_OSF1_THREADS) || defined(OSF1_THREADS) \ + +# include "private/gc_priv.h" +# if defined(HPUX_THREADS) && !defined(USE_PTHREAD_SPECIFIC) \ + && !defined(USE_HPUX_TLS) +# define USE_HPUX_TLS +# endif + +# ifdef THREAD_LOCAL_ALLOC +# if !defined(USE_PTHREAD_SPECIFIC) && !defined(USE_HPUX_TLS) +# include "private/specific.h" +# endif +# if defined(USE_PTHREAD_SPECIFIC) +# define GC_getspecific pthread_getspecific +# define GC_setspecific pthread_setspecific +# define GC_key_create pthread_key_create + typedef pthread_key_t GC_key_t; +# endif +# if defined(USE_HPUX_TLS) +# define GC_getspecific(x) (x) +# define GC_setspecific(key, v) ((key) = (v), 0) +# define GC_key_create(key, d) 0 + typedef void * GC_key_t; +# endif +# endif +# include <stdlib.h> # include <pthread.h> +# include <sched.h> # include <time.h> # include <errno.h> # include <unistd.h> # include <sys/mman.h> # include <sys/time.h> # include <semaphore.h> +# include <signal.h> +# include <sys/types.h> +# include <sys/stat.h> +# include <fcntl.h> + +#ifndef __GNUC__ +# define __inline__ +#endif + +#ifdef GC_USE_LD_WRAP +# define WRAP_FUNC(f) __wrap_##f +# define REAL_FUNC(f) __real_##f +#else +# define WRAP_FUNC(f) GC_##f +# define REAL_FUNC(f) f +# undef pthread_create +# undef pthread_sigmask +# undef pthread_join +# undef pthread_detach +#endif -#undef pthread_create -#undef pthread_sigmask -#undef pthread_join void GC_thr_init(); @@ -65,14 +127,13 @@ void GC_print_sig_mask() } #endif + /* We use the allocation lock to protect thread-related data structures. */ /* The set of all known threads. We intercept thread creation and */ -/* joins. We never actually create detached threads. We allocate all */ -/* new thread stacks ourselves. These allow us to maintain this */ -/* data structure. */ -/* Protected by GC_thr_lock. */ -/* Some of this should be declared volatile, but that's incosnsistent */ +/* joins. */ +/* Protected by allocation/GC lock. */ +/* Some of this should be declared volatile, but that's inconsistent */ /* with some library routine declarations. */ typedef struct GC_Thread_Rep { struct GC_Thread_Rep * next; /* More recently allocated threads */ @@ -81,42 +142,324 @@ typedef struct GC_Thread_Rep { /* guaranteed to be dead, but we may */ /* not yet have registered the join.) */ pthread_t id; - word flags; + short flags; # define FINISHED 1 /* Thread has exited. */ # define DETACHED 2 /* Thread is intended to be detached. */ # define MAIN_THREAD 4 /* True for the original thread only. */ - - ptr_t stack_end; - ptr_t stack_ptr; /* Valid only when stopped. */ + short thread_blocked; /* Protected by GC lock. */ + /* Treated as a boolean value. If set, */ + /* thread will acquire GC lock before */ + /* doing any pointer manipulations, and */ + /* has set its sp value. Thus it does */ + /* not need to be sent a signal to stop */ + /* it. */ + ptr_t stack_end; /* Cold end of the stack. */ + ptr_t stack_ptr; /* Valid only when stopped. */ +# ifdef IA64 + ptr_t backing_store_end; + ptr_t backing_store_ptr; +# endif int signal; void * status; /* The value returned from the thread. */ /* Used only to avoid premature */ /* reclamation of any data it might */ /* reference. */ +# ifdef THREAD_LOCAL_ALLOC +# if CPP_WORDSZ == 64 && defined(ALIGN_DOUBLE) +# define GRANULARITY 16 +# define NFREELISTS 49 +# else +# define GRANULARITY 8 +# define NFREELISTS 65 +# endif + /* The ith free list corresponds to size i*GRANULARITY */ +# define INDEX_FROM_BYTES(n) ((ADD_SLOP(n) + GRANULARITY - 1)/GRANULARITY) +# define BYTES_FROM_INDEX(i) ((i) * GRANULARITY - EXTRA_BYTES) +# define SMALL_ENOUGH(bytes) (ADD_SLOP(bytes) <= \ + (NFREELISTS-1)*GRANULARITY) + ptr_t ptrfree_freelists[NFREELISTS]; + ptr_t normal_freelists[NFREELISTS]; +# ifdef GC_GCJ_SUPPORT + ptr_t gcj_freelists[NFREELISTS]; +# endif + /* Free lists contain either a pointer or a small count */ + /* reflecting the number of granules allocated at that */ + /* size. */ + /* 0 ==> thread-local allocation in use, free list */ + /* empty. */ + /* > 0, <= DIRECT_GRANULES ==> Using global allocation, */ + /* too few objects of this size have been */ + /* allocated by this thread. */ + /* >= HBLKSIZE => pointer to nonempty free list. */ + /* > DIRECT_GRANULES, < HBLKSIZE ==> transition to */ + /* local alloc, equivalent to 0. */ +# define DIRECT_GRANULES (HBLKSIZE/GRANULARITY) + /* Don't use local free lists for up to this much */ + /* allocation. */ +# endif } * GC_thread; GC_thread GC_lookup_thread(pthread_t id); +static GC_bool parallel_initialized = FALSE; + +# if defined(__GNUC__) + void GC_init_parallel() __attribute__ ((constructor)); +# else + void GC_init_parallel(); +# endif + +# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL) + +/* We don't really support thread-local allocation with DBG_HDRS_ALL */ + +#ifdef USE_HPUX_TLS + __thread +#endif +GC_key_t GC_thread_key; + +static GC_bool keys_initialized; + +/* Recover the contents of the freelist array fl into the global one gfl.*/ +/* Note that the indexing scheme differs, in that gfl has finer size */ +/* resolution, even if not all entries are used. */ +/* We hold the allocator lock. */ +static void return_freelists(ptr_t *fl, ptr_t *gfl) +{ + int i; + ptr_t q, *qptr; + size_t nwords; + + for (i = 1; i < NFREELISTS; ++i) { + nwords = i * (GRANULARITY/sizeof(word)); + qptr = fl + i; + q = *qptr; + if ((word)q < HBLKSIZE) continue; + if (gfl[nwords] == 0) { + gfl[nwords] = q; + } else { + /* Concatenate: */ + for (; (word)q >= HBLKSIZE; qptr = &(obj_link(q)), q = *qptr); + GC_ASSERT(0 == q); + *qptr = gfl[nwords]; + gfl[nwords] = fl[i]; + } + /* Clear fl[i], since the thread structure may hang around. */ + /* Do it in a way that is likely to trap if we access it. */ + fl[i] = (ptr_t)HBLKSIZE; + } +} + +/* We statically allocate a single "size 0" object. It is linked to */ +/* itself, and is thus repeatedly reused for all size 0 allocation */ +/* requests. (Size 0 gcj allocation requests are incorrect, and */ +/* we arrange for those to fault asap.) */ +static ptr_t size_zero_object = (ptr_t)(&size_zero_object); + +/* Each thread structure must be initialized. */ +/* This call must be made from the new thread. */ +/* Caller holds allocation lock. */ +void GC_init_thread_local(GC_thread p) +{ + int i; + + if (!keys_initialized) { + if (0 != GC_key_create(&GC_thread_key, 0)) { + ABORT("Failed to create key for local allocator"); + } + keys_initialized = TRUE; + } + if (0 != GC_setspecific(GC_thread_key, p)) { + ABORT("Failed to set thread specific allocation pointers"); + } + for (i = 1; i < NFREELISTS; ++i) { + p -> ptrfree_freelists[i] = (ptr_t)1; + p -> normal_freelists[i] = (ptr_t)1; +# ifdef GC_GCJ_SUPPORT + p -> gcj_freelists[i] = (ptr_t)1; +# endif + } + /* Set up the size 0 free lists. */ + p -> ptrfree_freelists[0] = (ptr_t)(&size_zero_object); + p -> normal_freelists[0] = (ptr_t)(&size_zero_object); +# ifdef GC_GCJ_SUPPORT + p -> gcj_freelists[0] = (ptr_t)(-1); +# endif +} + +#ifdef GC_GCJ_SUPPORT + extern ptr_t * GC_gcjobjfreelist; +#endif + +/* We hold the allocator lock. */ +void GC_destroy_thread_local(GC_thread p) +{ + /* We currently only do this from the thread itself. */ + GC_ASSERT(GC_getspecific(GC_thread_key) == (void *)p); + return_freelists(p -> ptrfree_freelists, GC_aobjfreelist); + return_freelists(p -> normal_freelists, GC_objfreelist); +# ifdef GC_GCJ_SUPPORT + return_freelists(p -> gcj_freelists, GC_gcjobjfreelist); +# endif +} + +extern GC_PTR GC_generic_malloc_many(); + +GC_PTR GC_local_malloc(size_t bytes) +{ + if (EXPECT(!SMALL_ENOUGH(bytes),0)) { + return(GC_malloc(bytes)); + } else { + int index = INDEX_FROM_BYTES(bytes); + ptr_t * my_fl; + ptr_t my_entry; + GC_key_t k = GC_thread_key; + void * tsd; + +# if defined(REDIRECT_MALLOC) && !defined(USE_PTHREAD_SPECIFIC) \ + || !defined(__GNUC__) + if (EXPECT(0 == k, 0)) { + /* This can happen if we get called when the world is */ + /* being initialized. Whether we can actually complete */ + /* the initialization then is unclear. */ + GC_init_parallel(); + k = GC_thread_key; + } +# endif + tsd = GC_getspecific(GC_thread_key); +# ifdef GC_ASSERTIONS + LOCK(); + GC_ASSERT(tsd == (void *)GC_lookup_thread(pthread_self())); + UNLOCK(); +# endif + my_fl = ((GC_thread)tsd) -> normal_freelists + index; + my_entry = *my_fl; + if (EXPECT((word)my_entry >= HBLKSIZE, 1)) { + ptr_t next = obj_link(my_entry); + GC_PTR result = (GC_PTR)my_entry; + *my_fl = next; + obj_link(my_entry) = 0; + PREFETCH_FOR_WRITE(next); + return result; + } else if ((word)my_entry - 1 < DIRECT_GRANULES) { + *my_fl = my_entry + index + 1; + return GC_malloc(bytes); + } else { + GC_generic_malloc_many(BYTES_FROM_INDEX(index), NORMAL, my_fl); + if (*my_fl == 0) return GC_oom_fn(bytes); + return GC_local_malloc(bytes); + } + } +} + +GC_PTR GC_local_malloc_atomic(size_t bytes) +{ + if (EXPECT(!SMALL_ENOUGH(bytes), 0)) { + return(GC_malloc_atomic(bytes)); + } else { + int index = INDEX_FROM_BYTES(bytes); + ptr_t * my_fl = ((GC_thread)GC_getspecific(GC_thread_key)) + -> ptrfree_freelists + index; + ptr_t my_entry = *my_fl; + if (EXPECT((word)my_entry >= HBLKSIZE, 1)) { + GC_PTR result = (GC_PTR)my_entry; + *my_fl = obj_link(my_entry); + return result; + } else if ((word)my_entry - 1 < DIRECT_GRANULES) { + *my_fl = my_entry + index + 1; + return GC_malloc_atomic(bytes); + } else { + GC_generic_malloc_many(BYTES_FROM_INDEX(index), PTRFREE, my_fl); + /* *my_fl is updated while the collector is excluded; */ + /* the free list is always visible to the collector as */ + /* such. */ + if (*my_fl == 0) return GC_oom_fn(bytes); + return GC_local_malloc_atomic(bytes); + } + } +} + +#ifdef GC_GCJ_SUPPORT + +#include "include/gc_gcj.h" + +#ifdef GC_ASSERTIONS + extern GC_bool GC_gcj_malloc_initialized; +#endif + +extern int GC_gcj_kind; + +GC_PTR GC_local_gcj_malloc(size_t bytes, + void * ptr_to_struct_containing_descr) +{ + GC_ASSERT(GC_gcj_malloc_initialized); + if (EXPECT(!SMALL_ENOUGH(bytes), 0)) { + return GC_gcj_malloc(bytes, ptr_to_struct_containing_descr); + } else { + int index = INDEX_FROM_BYTES(bytes); + ptr_t * my_fl = ((GC_thread)GC_getspecific(GC_thread_key)) + -> gcj_freelists + index; + ptr_t my_entry = *my_fl; + if (EXPECT((word)my_entry >= HBLKSIZE, 1)) { + GC_PTR result = (GC_PTR)my_entry; + GC_ASSERT(!GC_incremental); + /* We assert that any concurrent marker will stop us. */ + /* Thus it is impossible for a mark procedure to see the */ + /* allocation of the next object, but to see this object */ + /* still containing a free list pointer. Otherwise the */ + /* marker might find a random "mark descriptor". */ + *(volatile ptr_t *)my_fl = obj_link(my_entry); + /* We must update the freelist before we store the pointer. */ + /* Otherwise a GC at this point would see a corrupted */ + /* free list. */ + /* A memory barrier is probably never needed, since the */ + /* action of stopping this thread will cause prior writes */ + /* to complete. */ + *(void * volatile *)result = ptr_to_struct_containing_descr; + return result; + } else if ((word)my_entry - 1 < DIRECT_GRANULES) { + *my_fl = my_entry + index + 1; + return GC_gcj_malloc(bytes, ptr_to_struct_containing_descr); + } else { + GC_generic_malloc_many(BYTES_FROM_INDEX(index), GC_gcj_kind, my_fl); + if (*my_fl == 0) return GC_oom_fn(bytes); + return GC_local_gcj_malloc(bytes, ptr_to_struct_containing_descr); + } + } +} + +#endif /* GC_GCJ_SUPPORT */ + +# else /* !THREAD_LOCAL_ALLOC && !DBG_HDRS_ALL */ + +# define GC_destroy_thread_local(t) + +# endif /* !THREAD_LOCAL_ALLOC */ + /* - * The only way to suspend threads given the pthread interface is to send - * signals. We can't use SIGSTOP directly, because we need to get the - * thread to save its stack pointer in the GC thread table before - * suspending. So we have to reserve a signal of our own for this. - * This means we have to intercept client calls to change the signal mask. - * The linuxthreads package already uses SIGUSR1 and SIGUSR2, - * so we need to reuse something else. I chose SIGPWR. - * (Perhaps SIGUNUSED would be a better choice.) + * We use signals to stop threads during GC. + * + * Suspended threads wait in signal handler for SIG_THR_RESTART. + * That's more portable than semaphores or condition variables. + * (We do use sem_post from a signal handler, but that should be portable.) + * + * The thread suspension signal SIG_SUSPEND is now defined in gc_priv.h. + * Note that we can't just stop a thread; we need it to save its stack + * pointer(s) and acknowledge. */ -#define SIG_SUSPEND SIGPWR -#define SIG_RESTART SIGXCPU +#ifndef SIG_THR_RESTART +# if defined(HPUX_THREADS) || defined(GC_OSF1_THREADS) +# define SIG_THR_RESTART _SIGRTMIN + 5 +# else +# define SIG_THR_RESTART SIGXCPU +# endif +#endif sem_t GC_suspend_ack_sem; +#if !defined(HPUX_THREADS) && !defined(GC_OSF1_THREADS) /* -GC_linux_thread_top_of_stack() relies on implementation details of -LinuxThreads, namely that thread stacks are allocated on 2M boundaries -and grow to no more than 2M. To make sure that we're using LinuxThreads and not some other thread package, we generate a dummy reference to `pthread_kill_other_threads_np' (was `__pthread_initial_thread_bos' but that disappeared), @@ -124,20 +467,90 @@ which is a symbol defined in LinuxThreads, but (hopefully) not in other thread packages. */ void (*dummy_var_to_force_linux_threads)() = pthread_kill_other_threads_np; +#endif /* !HPUX_THREADS */ + +#if defined(SPARC) || defined(IA64) + extern word GC_save_regs_in_stack(); +#endif + +long GC_nprocs = 1; /* Number of processors. We may not have */ + /* access to all of them, but this is as good */ + /* a guess as any ... */ + +#ifdef PARALLEL_MARK -#define LINUX_THREADS_STACK_SIZE (2 * 1024 * 1024) +# ifndef MAX_MARKERS +# define MAX_MARKERS 16 +# endif -static inline ptr_t GC_linux_thread_top_of_stack(void) +static ptr_t marker_sp[MAX_MARKERS] = {0}; + +void * GC_mark_thread(void * id) { - char *sp = GC_approx_sp(); - ptr_t tos = (ptr_t) (((unsigned long)sp | (LINUX_THREADS_STACK_SIZE - 1)) + 1); -#if DEBUG_THREADS - GC_printf1("SP = %lx\n", (unsigned long)sp); - GC_printf1("TOS = %lx\n", (unsigned long)tos); -#endif - return tos; + word my_mark_no = 0; + + marker_sp[(word)id] = GC_approx_sp(); + for (;; ++my_mark_no) { + /* GC_mark_no is passed only to allow GC_help_marker to terminate */ + /* promptly. This is important if it were called from the signal */ + /* handler or from the GC lock acquisition code. Under Linux, it's */ + /* not safe to call it from a signal handler, since it uses mutexes */ + /* and condition variables. Since it is called only here, the */ + /* argument is unnecessary. */ + if (my_mark_no < GC_mark_no || my_mark_no > GC_mark_no + 2) { + /* resynchronize if we get far off, e.g. because GC_mark_no */ + /* wrapped. */ + my_mark_no = GC_mark_no; + } +# ifdef DEBUG_THREADS + GC_printf1("Starting mark helper for mark number %ld\n", my_mark_no); +# endif + GC_help_marker(my_mark_no); + } +} + +extern long GC_markers; /* Number of mark threads we would */ + /* like to have. Includes the */ + /* initiating thread. */ + +pthread_t GC_mark_threads[MAX_MARKERS]; + +#define PTHREAD_CREATE REAL_FUNC(pthread_create) + +static void start_mark_threads() +{ + unsigned i; + pthread_attr_t attr; + + if (GC_markers > MAX_MARKERS) { + WARN("Limiting number of mark threads\n", 0); + GC_markers = MAX_MARKERS; + } + if (0 != pthread_attr_init(&attr)) ABORT("pthread_attr_init failed"); + + if (0 != pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED)) + ABORT("pthread_attr_setdetachstate failed"); +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf1("Starting %ld marker threads\n", GC_markers - 1); + } +# endif + for (i = 0; i < GC_markers - 1; ++i) { + if (0 != PTHREAD_CREATE(GC_mark_threads + i, &attr, + GC_mark_thread, (void *)(word)i)) { + WARN("Marker thread creation failed, errno = %ld.\n", errno); + } + } } +#else /* !PARALLEL_MARK */ + +static __inline__ void start_mark_threads() +{ +} + +#endif /* !PARALLEL_MARK */ + void GC_suspend_handler(int sig) { int dummy; @@ -147,6 +560,12 @@ void GC_suspend_handler(int sig) sigset_t old_sigs; int i; sigset_t mask; +# ifdef PARALLEL_MARK + word my_mark_no = GC_mark_no; + /* Marker can't proceed until we acknowledge. Thus this is */ + /* guaranteed to be the mark_no correspending to our */ + /* suspension, i.e. the marker can't have incremented it yet. */ +# endif if (sig != SIG_SUSPEND) ABORT("Bad signal in suspend_handler"); @@ -159,8 +578,14 @@ void GC_suspend_handler(int sig) /* of a thread which holds the allocation lock in order */ /* to stop the world. Thus concurrent modification of the */ /* data structure is impossible. */ - me -> stack_ptr = (ptr_t)(&dummy); - me -> stack_end = GC_linux_thread_top_of_stack(); +# ifdef SPARC + me -> stack_ptr = (ptr_t)GC_save_regs_in_stack(); +# else + me -> stack_ptr = (ptr_t)(&dummy); +# endif +# ifdef IA64 + me -> backing_store_ptr = (ptr_t)GC_save_regs_in_stack(); +# endif /* Tell the thread that wants to stop the world that this */ /* thread has been stopped. Note that sem_post() is */ @@ -168,15 +593,21 @@ void GC_suspend_handler(int sig) sem_post(&GC_suspend_ack_sem); /* Wait until that thread tells us to restart by sending */ - /* this thread a SIG_RESTART signal. */ - /* SIG_RESTART should be masked at this point. Thus there */ + /* this thread a SIG_THR_RESTART signal. */ + /* SIG_THR_RESTART should be masked at this point. Thus there */ /* is no race. */ if (sigfillset(&mask) != 0) ABORT("sigfillset() failed"); - if (sigdelset(&mask, SIG_RESTART) != 0) ABORT("sigdelset() failed"); + if (sigdelset(&mask, SIG_THR_RESTART) != 0) ABORT("sigdelset() failed"); +# ifdef NO_SIGNALS + if (sigdelset(&mask, SIGINT) != 0) ABORT("sigdelset() failed"); + if (sigdelset(&mask, SIGQUIT) != 0) ABORT("sigdelset() failed"); + if (sigdelset(&mask, SIGTERM) != 0) ABORT("sigdelset() failed"); + if (sigdelset(&mask, SIGABRT) != 0) ABORT("sigdelset() failed"); +# endif do { me->signal = 0; sigsuspend(&mask); /* Wait for signal */ - } while (me->signal != SIG_RESTART); + } while (me->signal != SIG_THR_RESTART); #if DEBUG_THREADS GC_printf1("Continuing 0x%x\n", my_thread); @@ -187,15 +618,15 @@ void GC_restart_handler(int sig) { GC_thread me; - if (sig != SIG_RESTART) ABORT("Bad signal in suspend_handler"); + if (sig != SIG_THR_RESTART) ABORT("Bad signal in suspend_handler"); - /* Let the GC_suspend_handler() know that we got a SIG_RESTART. */ + /* Let the GC_suspend_handler() know that we got a SIG_THR_RESTART. */ /* The lookup here is safe, since I'm doing this on behalf */ /* of a thread which holds the allocation lock in order */ /* to stop the world. Thus concurrent modification of the */ /* data structure is impossible. */ me = GC_lookup_thread(pthread_self()); - me->signal = SIG_RESTART; + me->signal = SIG_THR_RESTART; /* ** Note: even if we didn't do anything useful here, @@ -210,11 +641,57 @@ void GC_restart_handler(int sig) #endif } +/* Defining INSTALL_LOOPING_SEGV_HANDLER causes SIGSEGV and SIGBUS to */ +/* result in an infinite loop in a signal handler. This can be very */ +/* useful for debugging, since (as of RH7) gdb still seems to have */ +/* serious problems with threads. */ +#ifdef INSTALL_LOOPING_SEGV_HANDLER +void GC_looping_handler(int sig) +{ + GC_printf3("Signal %ld in thread %lx, pid %ld\n", + sig, pthread_self(), getpid()); + for (;;); +} +#endif + GC_bool GC_thr_initialized = FALSE; # define THREAD_TABLE_SZ 128 /* Must be power of 2 */ volatile GC_thread GC_threads[THREAD_TABLE_SZ]; +void GC_push_thread_structures GC_PROTO((void)) +{ + GC_push_all((ptr_t)(GC_threads), (ptr_t)(GC_threads)+sizeof(GC_threads)); +} + +#ifdef THREAD_LOCAL_ALLOC +/* We must explicitly mark ptrfree and gcj free lists, since the free */ +/* list links wouldn't otherwise be found. We also set them in the */ +/* normal free lists, since that involves touching less memory than if */ +/* we scanned them normally. */ +void GC_mark_thread_local_free_lists(void) +{ + int i, j; + GC_thread p; + ptr_t q; + + for (i = 0; i < THREAD_TABLE_SZ; ++i) { + for (p = GC_threads[i]; 0 != p; p = p -> next) { + for (j = 1; j < NFREELISTS; ++j) { + q = p -> ptrfree_freelists[j]; + if ((word)q > HBLKSIZE) GC_set_fl_marks(q); + q = p -> normal_freelists[j]; + if ((word)q > HBLKSIZE) GC_set_fl_marks(q); +# ifdef GC_GCJ_SUPPORT + q = p -> gcj_freelists[j]; + if ((word)q > HBLKSIZE) GC_set_fl_marks(q); +# endif /* GC_GCJ_SUPPORT */ + } + } + } +} +#endif /* THREAD_LOCAL_ALLOC */ + /* Add a thread to GC_threads. We assume it wasn't already there. */ /* Caller holds allocation lock. */ GC_thread GC_new_thread(pthread_t id) @@ -227,16 +704,15 @@ GC_thread GC_new_thread(pthread_t id) if (!first_thread_used) { result = &first_thread; first_thread_used = TRUE; - /* Dont acquire allocation lock, since we may already hold it. */ } else { result = (struct GC_Thread_Rep *) - GC_generic_malloc_inner(sizeof(struct GC_Thread_Rep), NORMAL); + GC_INTERNAL_MALLOC(sizeof(struct GC_Thread_Rep), NORMAL); } if (result == 0) return(0); result -> id = id; result -> next = GC_threads[hv]; GC_threads[hv] = result; - /* result -> flags = 0; */ + GC_ASSERT(result -> flags == 0 && result -> thread_blocked == 0); return(result); } @@ -258,6 +734,7 @@ void GC_delete_thread(pthread_t id) } else { prev -> next = p -> next; } + GC_INTERNAL_FREE(p); } /* If a thread has been joined, but we have not yet */ @@ -279,6 +756,7 @@ void GC_delete_gc_thread(pthread_t id, GC_thread gc_id) } else { prev -> next = p -> next; } + GC_INTERNAL_FREE(p); } /* Return a GC_thread corresponding to a given thread_t. */ @@ -296,6 +774,11 @@ GC_thread GC_lookup_thread(pthread_t id) return(p); } +/* There seems to be a very rare thread stopping problem. To help us */ +/* debug that, we save the ids of the stopping thread. */ +pthread_t GC_stopping_thread; +int GC_stopping_pid; + /* Caller holds allocation lock. */ void GC_stop_world() { @@ -305,10 +788,22 @@ void GC_stop_world() register int n_live_threads = 0; register int result; + GC_stopping_thread = my_thread; /* debugging only. */ + GC_stopping_pid = getpid(); /* debugging only. */ + /* Make sure all free list construction has stopped before we start. */ + /* No new construction can start, since free list construction is */ + /* required to acquire and release the GC lock before it starts, */ + /* and we have the lock. */ +# ifdef PARALLEL_MARK + GC_acquire_mark_lock(); + GC_ASSERT(GC_fl_builder_count == 0); + /* We should have previously waited for it to become zero. */ +# endif /* PARALLEL_MARK */ for (i = 0; i < THREAD_TABLE_SZ; i++) { for (p = GC_threads[i]; p != 0; p = p -> next) { if (p -> id != my_thread) { if (p -> flags & FINISHED) continue; + if (p -> thread_blocked) /* Will wait */ continue; n_live_threads++; #if DEBUG_THREADS GC_printf1("Sending suspend signal to 0x%x\n", p -> id); @@ -328,14 +823,20 @@ void GC_stop_world() } } for (i = 0; i < n_live_threads; i++) { - sem_wait(&GC_suspend_ack_sem); + if (0 != sem_wait(&GC_suspend_ack_sem)) + ABORT("sem_wait in handler failed"); } +# ifdef PARALLEL_MARK + GC_release_mark_lock(); +# endif #if DEBUG_THREADS - GC_printf1("World stopped 0x%x\n", pthread_self()); + GC_printf1("World stopped 0x%x\n", pthread_self()); #endif + GC_stopping_thread = 0; /* debugging only */ } -/* Caller holds allocation lock. */ +/* Caller holds allocation lock, and has held it continuously since */ +/* the world stopped. */ void GC_start_world() { pthread_t my_thread = pthread_self(); @@ -352,11 +853,12 @@ void GC_start_world() for (p = GC_threads[i]; p != 0; p = p -> next) { if (p -> id != my_thread) { if (p -> flags & FINISHED) continue; + if (p -> thread_blocked) continue; n_live_threads++; #if DEBUG_THREADS GC_printf1("Sending restart signal to 0x%x\n", p -> id); #endif - result = pthread_kill(p -> id, SIG_RESTART); + result = pthread_kill(p -> id, SIG_THR_RESTART); switch(result) { case ESRCH: /* Not really there anymore. Possible? */ @@ -375,13 +877,21 @@ void GC_start_world() #endif } -/* We hold allocation lock. We assume the world is stopped. */ +# ifdef IA64 +# define IF_IA64(x) x +# else +# define IF_IA64(x) +# endif +/* We hold allocation lock. Should do exactly the right thing if the */ +/* world is stopped. Should not fail if it isn't. */ void GC_push_all_stacks() { - register int i; - register GC_thread p; - register ptr_t sp = GC_approx_sp(); - register ptr_t lo, hi; + int i; + GC_thread p; + ptr_t sp = GC_approx_sp(); + ptr_t lo, hi; + /* On IA64, we also need to scan the register backing store. */ + IF_IA64(ptr_t bs_lo; ptr_t bs_hi;) pthread_t me = pthread_self(); if (!GC_thr_initialized) GC_thr_init(); @@ -392,34 +902,115 @@ void GC_push_all_stacks() for (p = GC_threads[i]; p != 0; p = p -> next) { if (p -> flags & FINISHED) continue; if (pthread_equal(p -> id, me)) { - lo = GC_approx_sp(); +# ifdef SPARC + lo = (ptr_t)GC_save_regs_in_stack(); +# else + lo = GC_approx_sp(); +# endif + IF_IA64(bs_hi = (ptr_t)GC_save_regs_in_stack();) } else { lo = p -> stack_ptr; + IF_IA64(bs_hi = p -> backing_store_ptr;) } if ((p -> flags & MAIN_THREAD) == 0) { - if (pthread_equal(p -> id, me)) { - hi = GC_linux_thread_top_of_stack(); - } else { - hi = p -> stack_end; - } + hi = p -> stack_end; + IF_IA64(bs_lo = p -> backing_store_end); } else { /* The original stack. */ hi = GC_stackbottom; + IF_IA64(bs_lo = BACKING_STORE_BASE;) } #if DEBUG_THREADS GC_printf3("Stack for thread 0x%lx = [%lx,%lx)\n", (unsigned long) p -> id, (unsigned long) lo, (unsigned long) hi); #endif - GC_push_all_stack(lo, hi); + if (0 == lo) ABORT("GC_push_all_stacks: sp not set!\n"); +# ifdef STACK_GROWS_UP + /* We got them backwards! */ + GC_push_all_stack(hi, lo); +# else + GC_push_all_stack(lo, hi); +# endif +# ifdef IA64 + if (pthread_equal(p -> id, me)) { + GC_push_all_eager(bs_lo, bs_hi); + } else { + GC_push_all_stack(bs_lo, bs_hi); + } +# endif } } } +#ifdef USE_PROC_FOR_LIBRARIES +int GC_segment_is_thread_stack(ptr_t lo, ptr_t hi) +{ + int i; + GC_thread p; + +# ifdef PARALLEL_MARK + for (i = 0; i < GC_markers; ++i) { + if (marker_sp[i] > lo & marker_sp[i] < hi) return 1; + } +# endif + for (i = 0; i < THREAD_TABLE_SZ; i++) { + for (p = GC_threads[i]; p != 0; p = p -> next) { + if (0 != p -> stack_end) { +# ifdef STACK_GROWS_UP + if (p -> stack_end >= lo && p -> stack_end < hi) return 1; +# else /* STACK_GROWS_DOWN */ + if (p -> stack_end > lo && p -> stack_end <= hi) return 1; +# endif + } + } + } + return 0; +} +#endif /* USE_PROC_FOR_LIBRARIES */ + +#ifdef LINUX_THREADS +/* Return the number of processors, or i<= 0 if it can't be determined. */ +int GC_get_nprocs() +{ + /* Should be "return sysconf(_SC_NPROCESSORS_ONLN);" but that */ + /* appears to be buggy in many cases. */ + /* We look for lines "cpu<n>" in /proc/stat. */ +# define STAT_BUF_SIZE 4096 +# if defined(GC_USE_LD_WRAP) +# define STAT_READ __real_read +# else +# define STAT_READ read +# endif + char stat_buf[STAT_BUF_SIZE]; + int f; + char c; + word result = 1; + /* Some old kernels only have a single "cpu nnnn ..." */ + /* entry in /proc/stat. We identify those as */ + /* uniprocessors. */ + size_t i, len = 0; + + f = open("/proc/stat", O_RDONLY); + if (f < 0 || (len = STAT_READ(f, stat_buf, STAT_BUF_SIZE)) < 100) { + WARN("Couldn't read /proc/stat\n", 0); + return -1; + } + for (i = 0; i < len - 100; ++i) { + if (stat_buf[i] == '\n' && stat_buf[i+1] == 'c' + && stat_buf[i+2] == 'p' && stat_buf[i+3] == 'u') { + int cpu_no = atoi(stat_buf + i + 4); + if (cpu_no >= result) result = cpu_no + 1; + } + } + return result; +} +#endif /* LINUX_THREADS */ /* We hold the allocation lock. */ void GC_thr_init() { + int dummy; GC_thread t; struct sigaction act; @@ -433,24 +1024,112 @@ void GC_thr_init() if (sigfillset(&act.sa_mask) != 0) { ABORT("sigfillset() failed"); } - /* SIG_RESTART is unmasked by the handler when necessary. */ +# ifdef NO_SIGNALS + if (sigdelset(&act.sa_mask, SIGINT) != 0 + || sigdelset(&act.sa_mask, SIGQUIT != 0) + || sigdelset(&act.sa_mask, SIGABRT != 0) + || sigdelset(&act.sa_mask, SIGTERM != 0)) { + ABORT("sigdelset() failed"); + } +# endif + + /* SIG_THR_RESTART is unmasked by the handler when necessary. */ act.sa_handler = GC_suspend_handler; if (sigaction(SIG_SUSPEND, &act, NULL) != 0) { ABORT("Cannot set SIG_SUSPEND handler"); } act.sa_handler = GC_restart_handler; - if (sigaction(SIG_RESTART, &act, NULL) != 0) { - ABORT("Cannot set SIG_SUSPEND handler"); + if (sigaction(SIG_THR_RESTART, &act, NULL) != 0) { + ABORT("Cannot set SIG_THR_RESTART handler"); } +# ifdef INSTALL_LOOPING_SEGV_HANDLER + act.sa_handler = GC_looping_handler; + if (sigaction(SIGSEGV, &act, NULL) != 0 + || sigaction(SIGBUS, &act, NULL) != 0) { + ABORT("Cannot set SIGSEGV or SIGBUS looping handler"); + } +# endif /* INSTALL_LOOPING_SEGV_HANDLER */ /* Add the initial thread, so we can stop it. */ t = GC_new_thread(pthread_self()); - t -> stack_ptr = 0; + t -> stack_ptr = (ptr_t)(&dummy); t -> flags = DETACHED | MAIN_THREAD; + + /* Set GC_nprocs. */ + { + char * nprocs_string = GETENV("GC_NPROCS"); + GC_nprocs = -1; + if (nprocs_string != NULL) GC_nprocs = atoi(nprocs_string); + } + if (GC_nprocs <= 0) { +# if defined(HPUX_THREADS) + GC_nprocs = pthread_num_processors_np(); +# endif +# if defined(OSF1_THREADS) + GC_nprocs = 1; +# endif +# ifdef LINUX_THREADS + GC_nprocs = GC_get_nprocs(); +# endif + } + if (GC_nprocs <= 0) { + WARN("GC_get_nprocs() returned %ld\n", GC_nprocs); + GC_nprocs = 2; +# ifdef PARALLEL_MARK + GC_markers = 1; +# endif + } else { +# ifdef PARALLEL_MARK + GC_markers = GC_nprocs; +# endif + } +# ifdef PARALLEL_MARK +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf2("Number of processors = %ld, " + "number of marker threads = %ld\n", GC_nprocs, GC_markers); + } +# endif + if (GC_markers == 1) { + GC_parallel = FALSE; +# ifdef CONDPRINT + if (GC_print_stats) { + GC_printf0("Single marker thread, turning off parallel marking\n"); + } +# endif + } else { + GC_parallel = TRUE; + } +# endif +} + + +/* Perform all initializations, including those that */ +/* may require allocation. */ +/* Called as constructor without allocation lock. */ +/* Must be called before a second thread is created. */ +/* Called without allocation lock. */ +void GC_init_parallel() +{ + if (parallel_initialized) return; + parallel_initialized = TRUE; + /* GC_init() calls us back, so set flag first. */ + if (!GC_is_initialized) GC_init(); + /* If we are using a parallel marker, start the helper threads. */ +# ifdef PARALLEL_MARK + if (GC_parallel) start_mark_threads(); +# endif + /* Initialize thread local free lists if used. */ +# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL) + LOCK(); + GC_init_thread_local(GC_lookup_thread(pthread_self())); + UNLOCK(); +# endif } -int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) + +int WRAP_FUNC(pthread_sigmask)(int how, const sigset_t *set, sigset_t *oset) { sigset_t fudged_set; @@ -459,7 +1138,57 @@ int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) sigdelset(&fudged_set, SIG_SUSPEND); set = &fudged_set; } - return(pthread_sigmask(how, set, oset)); + return(REAL_FUNC(pthread_sigmask)(how, set, oset)); +} + +/* Wrappers for functions that are likely to block for an appreciable */ +/* length of time. Must be called in pairs, if at all. */ +/* Nothing much beyond the system call itself should be executed */ +/* between these. */ + +void GC_start_blocking(void) { +# define SP_SLOP 128 + GC_thread me; + LOCK(); + me = GC_lookup_thread(pthread_self()); + GC_ASSERT(!(me -> thread_blocked)); +# ifdef SPARC + me -> stack_ptr = (ptr_t)GC_save_regs_in_stack(); +# else + me -> stack_ptr = (ptr_t)GC_approx_sp(); +# endif +# ifdef IA64 + me -> backing_store_ptr = (ptr_t)GC_save_regs_in_stack() + SP_SLOP; +# endif + /* Add some slop to the stack pointer, since the wrapped call may */ + /* end up pushing more callee-save registers. */ +# ifdef STACK_GROWS_UP + me -> stack_ptr += SP_SLOP; +# else + me -> stack_ptr -= SP_SLOP; +# endif + me -> thread_blocked = TRUE; + UNLOCK(); +} + +GC_end_blocking(void) { + GC_thread me; + LOCK(); /* This will block if the world is stopped. */ + me = GC_lookup_thread(pthread_self()); + GC_ASSERT(me -> thread_blocked); + me -> thread_blocked = FALSE; + UNLOCK(); +} + +/* A wrapper for the standard C sleep function */ +int WRAP_FUNC(sleep) (unsigned int seconds) +{ + int result; + + GC_start_blocking(); + result = REAL_FUNC(sleep)(seconds); + GC_end_blocking(); + return result; } struct start_info { @@ -470,23 +1199,46 @@ struct start_info { /* parent hasn't yet noticed. */ }; - +/* Called at thread exit. */ +/* Never called for main thread. That's OK, since it */ +/* results in at most a tiny one-time leak. And */ +/* linuxthreads doesn't reclaim the main threads */ +/* resources or id anyway. */ void GC_thread_exit_proc(void *arg) { GC_thread me; - struct start_info * si = arg; LOCK(); me = GC_lookup_thread(pthread_self()); + GC_destroy_thread_local(me); if (me -> flags & DETACHED) { GC_delete_thread(pthread_self()); } else { me -> flags |= FINISHED; } +# if defined(THREAD_LOCAL_ALLOC) && !defined(USE_PTHREAD_SPECIFIC) \ + && !defined(USE_HPUX_TLS) && !defined(DBG_HDRS_ALL) + GC_remove_specific(GC_thread_key); +# endif + if (GC_incremental && GC_collection_in_progress()) { + int old_gc_no = GC_gc_no; + + /* Make sure that no part of our stack is still on the mark stack, */ + /* since it's about to be unmapped. */ + while (GC_incremental && GC_collection_in_progress() + && old_gc_no == GC_gc_no) { + ENTER_GC(); + GC_collect_a_little_inner(1); + EXIT_GC(); + UNLOCK(); + sched_yield(); + LOCK(); + } + } UNLOCK(); } -int GC_pthread_join(pthread_t thread, void **retval) +int WRAP_FUNC(pthread_join)(pthread_t thread, void **retval) { int result; GC_thread thread_gc_id; @@ -496,16 +1248,41 @@ int GC_pthread_join(pthread_t thread, void **retval) /* This is guaranteed to be the intended one, since the thread id */ /* cant have been recycled by pthreads. */ UNLOCK(); - result = pthread_join(thread, retval); + result = REAL_FUNC(pthread_join)(thread, retval); + if (result == 0) { + LOCK(); + /* Here the pthread thread id may have been recycled. */ + GC_delete_gc_thread(thread, thread_gc_id); + UNLOCK(); + } + return result; +} + +int +WRAP_FUNC(pthread_detach)(pthread_t thread) +{ + int result; + GC_thread thread_gc_id; + LOCK(); - /* Here the pthread thread id may have been recycled. */ - GC_delete_gc_thread(thread, thread_gc_id); + thread_gc_id = GC_lookup_thread(thread); UNLOCK(); + result = REAL_FUNC(pthread_detach)(thread); + if (result == 0) { + LOCK(); + thread_gc_id -> flags |= DETACHED; + /* Here the pthread thread id may have been recycled. */ + if (thread_gc_id -> flags & FINISHED) { + GC_delete_gc_thread(thread, thread_gc_id); + } + UNLOCK(); + } return result; } void * GC_start_routine(void * arg) { + int dummy; struct start_info * si = arg; void * result; GC_thread me; @@ -514,22 +1291,51 @@ void * GC_start_routine(void * arg) void *start_arg; my_pthread = pthread_self(); +# ifdef DEBUG_THREADS + GC_printf1("Starting thread 0x%lx\n", my_pthread); + GC_printf1("pid = %ld\n", (long) getpid()); + GC_printf1("sp = 0x%lx\n", (long) &arg); +# endif LOCK(); me = GC_new_thread(my_pthread); me -> flags = si -> flags; me -> stack_ptr = 0; - me -> stack_end = 0; + /* me -> stack_end = GC_linux_stack_base(); -- currently (11/99) */ + /* doesn't work because the stack base in /proc/self/stat is the */ + /* one for the main thread. There is a strong argument that that's */ + /* a kernel bug, but a pervasive one. */ +# ifdef STACK_GROWS_DOWN + me -> stack_end = (ptr_t)(((word)(&dummy) + (GC_page_size - 1)) + & ~(GC_page_size - 1)); + me -> stack_ptr = me -> stack_end - 0x10; + /* Needs to be plausible, since an asynchronous stack mark */ + /* should not crash. */ +# else + me -> stack_end = (ptr_t)((word)(&dummy) & ~(GC_page_size - 1)); + me -> stack_ptr = me -> stack_end + 0x10; +# endif + /* This is dubious, since we may be more than a page into the stack, */ + /* and hence skip some of it, though it's not clear that matters. */ +# ifdef IA64 + me -> backing_store_end = (ptr_t) + (GC_save_regs_in_stack() & ~(GC_page_size - 1)); + /* This is also < 100% convincing. We should also read this */ + /* from /proc, but the hook to do so isn't there yet. */ +# endif /* IA64 */ UNLOCK(); start = si -> start_routine; - start_arg = si -> arg; - sem_post(&(si -> registered)); - pthread_cleanup_push(GC_thread_exit_proc, si); # ifdef DEBUG_THREADS - GC_printf1("Starting thread 0x%lx\n", pthread_self()); - GC_printf1("pid = %ld\n", (long) getpid()); - GC_printf1("sp = 0x%lx\n", (long) &arg); GC_printf1("start_routine = 0x%lx\n", start); # endif + start_arg = si -> arg; + sem_post(&(si -> registered)); /* Last action on si. */ + /* OK to deallocate. */ + pthread_cleanup_push(GC_thread_exit_proc, 0); +# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL) + LOCK(); + GC_init_thread_local(me); + UNLOCK(); +# endif result = (*start)(start_arg); #if DEBUG_THREADS GC_printf1("Finishing thread 0x%x\n", pthread_self()); @@ -544,22 +1350,23 @@ void * GC_start_routine(void * arg) } int -GC_pthread_create(pthread_t *new_thread, +WRAP_FUNC(pthread_create)(pthread_t *new_thread, const pthread_attr_t *attr, void *(*start_routine)(void *), void *arg) { int result; GC_thread t; pthread_t my_new_thread; - void * stack; - size_t stacksize; - pthread_attr_t new_attr; int detachstate; word my_flags = 0; - struct start_info * si = GC_malloc(sizeof(struct start_info)); + struct start_info * si; /* This is otherwise saved only in an area mmapped by the thread */ /* library, which isn't visible to the collector. */ - + + LOCK(); + si = (struct start_info *)GC_INTERNAL_MALLOC(sizeof(struct start_info), NORMAL); + UNLOCK(); + if (!parallel_initialized) GC_init_parallel(); if (0 == si) return(ENOMEM); sem_init(&(si -> registered), 0, 0); si -> start_routine = start_routine; @@ -567,32 +1374,132 @@ GC_pthread_create(pthread_t *new_thread, LOCK(); if (!GC_thr_initialized) GC_thr_init(); if (NULL == attr) { - stack = 0; - (void) pthread_attr_init(&new_attr); + detachstate = PTHREAD_CREATE_JOINABLE; } else { - new_attr = *attr; + pthread_attr_getdetachstate(attr, &detachstate); } - pthread_attr_getdetachstate(&new_attr, &detachstate); if (PTHREAD_CREATE_DETACHED == detachstate) my_flags |= DETACHED; si -> flags = my_flags; UNLOCK(); - result = pthread_create(new_thread, &new_attr, GC_start_routine, si); +# ifdef DEBUG_THREADS + GC_printf1("About to start new thread from thread 0x%X\n", + pthread_self()); +# endif + result = REAL_FUNC(pthread_create)(new_thread, attr, GC_start_routine, si); +# ifdef DEBUG_THREADS + GC_printf1("Started thread 0x%X\n", *new_thread); +# endif /* Wait until child has been added to the thread table. */ /* This also ensures that we hold onto si until the child is done */ /* with it. Thus it doesn't matter whether it is otherwise */ /* visible to the collector. */ - if (0 != sem_wait(&(si -> registered))) ABORT("sem_wait failed"); + while (0 != sem_wait(&(si -> registered))) { + if (EINTR != errno) ABORT("sem_wait failed"); + } sem_destroy(&(si -> registered)); - /* pthread_attr_destroy(&new_attr); */ - /* pthread_attr_destroy(&new_attr); */ + LOCK(); + GC_INTERNAL_FREE(si); + UNLOCK(); return(result); } -GC_bool GC_collecting = 0; +#ifdef GENERIC_COMPARE_AND_SWAP + pthread_mutex_t GC_compare_and_swap_lock = PTHREAD_MUTEX_INITIALIZER; + + GC_bool GC_compare_and_exchange(volatile GC_word *addr, + GC_word old, GC_word new_val) + { + GC_bool result; + pthread_mutex_lock(&GC_compare_and_swap_lock); + if (*addr == old) { + *addr = new_val; + result = TRUE; + } else { + result = FALSE; + } + pthread_mutex_unlock(&GC_compare_and_swap_lock); + return result; + } + + GC_word GC_atomic_add(volatile GC_word *addr, GC_word how_much) + { + GC_word old; + pthread_mutex_lock(&GC_compare_and_swap_lock); + old = *addr; + *addr = old + how_much; + pthread_mutex_unlock(&GC_compare_and_swap_lock); + return old; + } + +#endif /* GENERIC_COMPARE_AND_SWAP */ +/* Spend a few cycles in a way that can't introduce contention with */ +/* othre threads. */ +void GC_pause() +{ + int i; + volatile word dummy = 0; + + for (i = 0; i < 10; ++i) { +# ifdef __GNUC__ + __asm__ __volatile__ (" " : : : "memory"); +# else + /* Something that's unlikely to be optimized away. */ + GC_noop(++dummy); +# endif + } +} + +#define SPIN_MAX 1024 /* Maximum number of calls to GC_pause before */ + /* give up. */ + +VOLATILE GC_bool GC_collecting = 0; /* A hint that we're in the collector and */ /* holding the allocation lock for an */ /* extended period. */ +#if !defined(USE_SPIN_LOCK) || defined(PARALLEL_MARK) +/* If we don't want to use the below spinlock implementation, either */ +/* because we don't have a GC_test_and_set implementation, or because */ +/* we don't want to risk sleeping, we can still try spinning on */ +/* pthread_mutex_trylock for a while. This appears to be very */ +/* beneficial in many cases. */ +/* I suspect that under high contention this is nearly always better */ +/* than the spin lock. But it's a bit slower on a uniprocessor. */ +/* Hence we still default to the spin lock. */ +/* This is also used to acquire the mark lock for the parallel */ +/* marker. */ + +/* Here we use a strict exponential backoff scheme. I don't know */ +/* whether that's better or worse than the above. We eventually */ +/* yield by calling pthread_mutex_lock(); it never makes sense to */ +/* explicitly sleep. */ + +void GC_generic_lock(pthread_mutex_t * lock) +{ + unsigned pause_length = 1; + unsigned i; + + if (0 == pthread_mutex_trylock(lock)) return; + for (; pause_length <= SPIN_MAX; pause_length <<= 1) { + for (i = 0; i < pause_length; ++i) { + GC_pause(); + } + switch(pthread_mutex_trylock(lock)) { + case 0: + return; + case EBUSY: + break; + default: + ABORT("Unexpected error from pthread_mutex_trylock"); + } + } + pthread_mutex_lock(lock); +} + +#endif /* !USE_SPIN_LOCK || PARALLEL_MARK */ + +#if defined(USE_SPIN_LOCK) + /* Reasonably fast spin locks. Basically the same implementation */ /* as STL alloc.h. This isn't really the right way to do this. */ /* but until the POSIX scheduling mess gets straightened out ... */ @@ -603,25 +1510,22 @@ volatile unsigned int GC_allocate_lock = 0; void GC_lock() { # define low_spin_max 30 /* spin cycles if we suspect uniprocessor */ -# define high_spin_max 1000 /* spin cycles for multiprocessor */ +# define high_spin_max SPIN_MAX /* spin cycles for multiprocessor */ static unsigned spin_max = low_spin_max; unsigned my_spin_max; static unsigned last_spins = 0; unsigned my_last_spins; - volatile unsigned junk; -# define PAUSE junk *= junk; junk *= junk; junk *= junk; junk *= junk int i; if (!GC_test_and_set(&GC_allocate_lock)) { return; } - junk = 0; my_spin_max = spin_max; my_last_spins = last_spins; for (i = 0; i < my_spin_max; i++) { - if (GC_collecting) goto yield; + if (GC_collecting || GC_nprocs == 1) goto yield; if (i < my_last_spins/2 || GC_allocate_lock) { - PAUSE; + GC_pause(); continue; } if (!GC_test_and_set(&GC_allocate_lock)) { @@ -651,8 +1555,8 @@ yield: } else { struct timespec ts; - if (i > 26) i = 26; - /* Don't wait for more than about 60msecs, even */ + if (i > 24) i = 24; + /* Don't wait for more than about 15msecs, even */ /* under extreme contention. */ ts.tv_sec = 0; ts.tv_nsec = 1 << i; @@ -661,5 +1565,131 @@ yield: } } +#else /* !USE_SPINLOCK */ + +void GC_lock() +{ + if (1 == GC_nprocs || GC_collecting) { + pthread_mutex_lock(&GC_allocate_ml); + } else { + GC_generic_lock(&GC_allocate_ml); + } +} + +#endif /* !USE_SPINLOCK */ + +#if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC) + +#ifdef GC_ASSERTIONS + pthread_t GC_mark_lock_holder = NO_THREAD; +#endif + +#ifdef IA64 + /* Ugly workaround for a linux threads bug in the final versions */ + /* of glibc2.1. Pthread_mutex_trylock sets the mutex owner */ + /* field even when it fails to acquire the mutex. This causes */ + /* pthread_cond_wait to die. Remove for glibc2.2. */ + /* According to the man page, we should use */ + /* PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, but that isn't actually */ + /* defined. */ + static pthread_mutex_t mark_mutex = + {0, 0, 0, PTHREAD_MUTEX_ERRORCHECK_NP, {0, 0}}; +#else + static pthread_mutex_t mark_mutex = PTHREAD_MUTEX_INITIALIZER; +#endif + +static pthread_cond_t builder_cv = PTHREAD_COND_INITIALIZER; + +void GC_acquire_mark_lock() +{ +/* + if (pthread_mutex_lock(&mark_mutex) != 0) { + ABORT("pthread_mutex_lock failed"); + } +*/ + GC_generic_lock(&mark_mutex); +# ifdef GC_ASSERTIONS + GC_mark_lock_holder = pthread_self(); +# endif +} + +void GC_release_mark_lock() +{ + GC_ASSERT(GC_mark_lock_holder == pthread_self()); +# ifdef GC_ASSERTIONS + GC_mark_lock_holder = NO_THREAD; +# endif + if (pthread_mutex_unlock(&mark_mutex) != 0) { + ABORT("pthread_mutex_unlock failed"); + } +} + +/* Collector must wait for a freelist builders for 2 reasons: */ +/* 1) Mark bits may still be getting examined without lock. */ +/* 2) Partial free lists referenced only by locals may not be scanned */ +/* correctly, e.g. if they contain "pointer-free" objects, since the */ +/* free-list link may be ignored. */ +void GC_wait_builder() +{ + GC_ASSERT(GC_mark_lock_holder == pthread_self()); +# ifdef GC_ASSERTIONS + GC_mark_lock_holder = NO_THREAD; +# endif + if (pthread_cond_wait(&builder_cv, &mark_mutex) != 0) { + ABORT("pthread_cond_wait failed"); + } + GC_ASSERT(GC_mark_lock_holder == NO_THREAD); +# ifdef GC_ASSERTIONS + GC_mark_lock_holder = pthread_self(); +# endif +} + +void GC_wait_for_reclaim() +{ + GC_acquire_mark_lock(); + while (GC_fl_builder_count > 0) { + GC_wait_builder(); + } + GC_release_mark_lock(); +} + +void GC_notify_all_builder() +{ + GC_ASSERT(GC_mark_lock_holder == pthread_self()); + if (pthread_cond_broadcast(&builder_cv) != 0) { + ABORT("pthread_cond_broadcast failed"); + } +} + +#endif /* PARALLEL_MARK || THREAD_LOCAL_ALLOC */ + +#ifdef PARALLEL_MARK + +static pthread_cond_t mark_cv = PTHREAD_COND_INITIALIZER; + +void GC_wait_marker() +{ + GC_ASSERT(GC_mark_lock_holder == pthread_self()); +# ifdef GC_ASSERTIONS + GC_mark_lock_holder = NO_THREAD; +# endif + if (pthread_cond_wait(&mark_cv, &mark_mutex) != 0) { + ABORT("pthread_cond_wait failed"); + } + GC_ASSERT(GC_mark_lock_holder == NO_THREAD); +# ifdef GC_ASSERTIONS + GC_mark_lock_holder = pthread_self(); +# endif +} + +void GC_notify_all_marker() +{ + if (pthread_cond_broadcast(&mark_cv) != 0) { + ABORT("pthread_cond_broadcast failed"); + } +} + +#endif /* PARALLEL_MARK */ + # endif /* LINUX_THREADS */ |