mono/metadata/sgen-stw.c

   1 /*
   2  * sgen-stw.c: Stop the world functionality
   3  *
   4  * Author:
   5  *      Paolo Molaro (lupus@ximian.com)
   6  *  Rodrigo Kumpera (kumpera@gmail.com)
   7  *
   8  * Copyright 2005-2011 Novell, Inc (http://www.novell.com)
   9  * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
  10  * Copyright 2011 Xamarin, Inc.
  11  * Copyright (C) 2012 Xamarin Inc
  12  *
  13  * This library is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU Library General Public
  15  * License 2.0 as published by the Free Software Foundation;
  16  *
  17  * This library is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License 2.0 along with this library; if not, write to the Free
  24  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  25  */
  26
  27 #include "config.h"
  28 #ifdef HAVE_SGEN_GC
  29
  30 #include "metadata/sgen-gc.h"
  31 #include "metadata/sgen-protocol.h"
  32 #include "metadata/sgen-memory-governor.h"
  33 #include "metadata/profiler-private.h"
  34 #include "utils/mono-time.h"
  35 #include "utils/dtrace.h"
  36
  37 #define TV_DECLARE SGEN_TV_DECLARE
  38 #define TV_GETTIME SGEN_TV_GETTIME
  39 #define TV_ELAPSED SGEN_TV_ELAPSED
  40 #define TV_ELAPSED_MS SGEN_TV_ELAPSED_MS
  41
  42 inline static void*
  43 align_pointer (void *ptr)
  44 {
  45         mword p = (mword)ptr;
  46         p += sizeof (gpointer) - 1;
  47         p &= ~ (sizeof (gpointer) - 1);
  48         return (void*)p;
  49 }
  50
  51 #ifdef USE_MONO_CTX
  52 static MonoContext cur_thread_ctx = {0};
  53 #else
  54 static mword cur_thread_regs [ARCH_NUM_REGS] = {0};
  55 #endif
  56
  57 static void
  58 update_current_thread_stack (void *start)
  59 {
  60         int stack_guard = 0;
  61 #if !defined(USE_MONO_CTX)
  62         void *reg_ptr = cur_thread_regs;
  63 #endif
  64         SgenThreadInfo *info = mono_thread_info_current ();
  65
  66         info->stack_start = align_pointer (&stack_guard);
  67         g_assert (info->stack_start >= info->stack_start_limit && info->stack_start < info->stack_end);
  68 #ifdef USE_MONO_CTX
  69         MONO_CONTEXT_GET_CURRENT (cur_thread_ctx);
  70         memcpy (&info->ctx, &cur_thread_ctx, sizeof (MonoContext));
  71         if (mono_gc_get_gc_callbacks ()->thread_suspend_func)
  72                 mono_gc_get_gc_callbacks ()->thread_suspend_func (info->runtime_data, NULL, &info->ctx);
  73 #else
  74         ARCH_STORE_REGS (reg_ptr);
  75         memcpy (&info->regs, reg_ptr, sizeof (info->regs));
  76         if (mono_gc_get_gc_callbacks ()->thread_suspend_func)
  77                 mono_gc_get_gc_callbacks ()->thread_suspend_func (info->runtime_data, NULL, NULL);
  78 #endif
  79 }
  80
  81 static gboolean
  82 is_ip_in_managed_allocator (MonoDomain *domain, gpointer ip)
  83 {
  84         MonoJitInfo *ji;
  85
  86         if (!mono_thread_internal_current ())
  87                 /* Happens during thread attach */
  88                 return FALSE;
  89
  90         if (!ip || !domain)
  91                 return FALSE;
  92         if (!sgen_has_critical_method ())
  93                 return FALSE;
  94
  95         /*
  96          * mono_jit_info_table_find is not async safe since it calls into the AOT runtime to load information for
  97          * missing methods (#13951). To work around this, we disable the AOT fallback. For this to work, the JIT needs
  98          * to register the jit info for all GC critical methods after they are JITted/loaded.
  99          */
 100         ji = mono_jit_info_table_find_internal (domain, ip, FALSE);
 101         if (!ji)
 102                 return FALSE;
 103
 104         return sgen_is_critical_method (mono_jit_info_get_method (ji));
 105 }
 106
 107 static int
 108 restart_threads_until_none_in_managed_allocator (void)
 109 {
 110         SgenThreadInfo *info;
 111         int num_threads_died = 0;
 112         int sleep_duration = -1;
 113
 114         for (;;) {
 115                 int restart_count = 0, restarted_count = 0;
 116                 /* restart all threads that stopped in the
 117                    allocator */
 118                 FOREACH_THREAD_SAFE (info) {
 119                         gboolean result;
 120                         if (info->skip || info->gc_disabled)
 121                                 continue;
 122 #ifdef SGEN_POSIX_STW
 123                         if (info->signal < 0)
 124                                 continue;
 125 #endif
 126                         if (mono_thread_info_run_state (info) == STATE_RUNNING && (!info->stack_start || info->in_critical_region || info->info.inside_critical_region ||
 127                                         is_ip_in_managed_allocator (info->stopped_domain, info->stopped_ip))) {
 128                                 binary_protocol_thread_restart ((gpointer)mono_thread_info_get_tid (info));
 129                                 SGEN_LOG (3, "thread %p resumed.", (void*) (size_t) info->info.native_handle);
 130                                 result = sgen_resume_thread (info);
 131                                 if (result) {
 132                                         ++restart_count;
 133                                 } else {
 134                                         info->skip = 1;
 135                                 }
 136                         } else {
 137                                 /* we set the stopped_ip to
 138                                    NULL for threads which
 139                                    we're not restarting so
 140                                    that we can easily identify
 141                                    the others */
 142                                 info->stopped_ip = NULL;
 143                                 info->stopped_domain = NULL;
 144                         }
 145                 } END_FOREACH_THREAD_SAFE
 146                 /* if no threads were restarted, we're done */
 147                 if (restart_count == 0)
 148                         break;
 149
 150                 /* wait for the threads to signal their restart */
 151                 sgen_wait_for_suspend_ack (restart_count);
 152
 153                 if (sleep_duration < 0) {
 154 #ifdef HOST_WIN32
 155                         SwitchToThread ();
 156 #else
 157                         sched_yield ();
 158 #endif
 159                         sleep_duration = 0;
 160                 } else {
 161                         g_usleep (sleep_duration);
 162                         sleep_duration += 10;
 163                 }
 164
 165                 /* stop them again */
 166                 FOREACH_THREAD (info) {
 167                         gboolean result;
 168                         if (info->skip || info->stopped_ip == NULL)
 169                                 continue;
 170                         result = sgen_suspend_thread (info);
 171
 172                         if (result) {
 173                                 ++restarted_count;
 174                         } else {
 175                                 info->skip = 1;
 176                         }
 177                 } END_FOREACH_THREAD
 178                 /* some threads might have died */
 179                 num_threads_died += restart_count - restarted_count;
 180                 /* wait for the threads to signal their suspension
 181                    again */
 182                 sgen_wait_for_suspend_ack (restarted_count);
 183         }
 184
 185         return num_threads_died;
 186 }
 187
 188 static void
 189 acquire_gc_locks (void)
 190 {
 191         LOCK_INTERRUPTION;
 192         mono_thread_info_suspend_lock ();
 193 }
 194
 195 static void
 196 release_gc_locks (void)
 197 {
 198         mono_thread_info_suspend_unlock ();
 199         UNLOCK_INTERRUPTION;
 200 }
 201
 202 static TV_DECLARE (stop_world_time);
 203 static unsigned long max_pause_usec = 0;
 204
 205 /* LOCKING: assumes the GC lock is held */
 206 int
 207 sgen_stop_world (int generation)
 208 {
 209         int count, dead;
 210
 211         /*XXX this is the right stop, thought might not be the nicest place to put it*/
 212         sgen_process_togglerefs ();
 213
 214         mono_profiler_gc_event (MONO_GC_EVENT_PRE_STOP_WORLD, generation);
 215         MONO_GC_WORLD_STOP_BEGIN ();
 216         acquire_gc_locks ();
 217
 218         update_current_thread_stack (&count);
 219
 220         sgen_global_stop_count++;
 221         SGEN_LOG (3, "stopping world n %d from %p %p", sgen_global_stop_count, mono_thread_info_current (), (gpointer)mono_native_thread_id_get ());
 222         TV_GETTIME (stop_world_time);
 223         count = sgen_thread_handshake (TRUE);
 224         dead = restart_threads_until_none_in_managed_allocator ();
 225         if (count < dead)
 226                 g_error ("More threads have died (%d) that been initialy suspended %d", dead, count);
 227         count -= dead;
 228
 229         SGEN_LOG (3, "world stopped %d thread(s)", count);
 230         mono_profiler_gc_event (MONO_GC_EVENT_POST_STOP_WORLD, generation);
 231         MONO_GC_WORLD_STOP_END ();
 232
 233         sgen_memgov_collection_start (generation);
 234         sgen_bridge_reset_data ();
 235
 236         return count;
 237 }
 238
 239 /* LOCKING: assumes the GC lock is held */
 240 int
 241 sgen_restart_world (int generation, GGTimingInfo *timing)
 242 {
 243         int count;
 244         SgenThreadInfo *info;
 245         TV_DECLARE (end_sw);
 246         TV_DECLARE (end_bridge);
 247         unsigned long usec, bridge_usec;
 248
 249         /* notify the profiler of the leftovers */
 250         /* FIXME this is the wrong spot at we can STW for non collection reasons. */
 251         if (G_UNLIKELY (mono_profiler_events & MONO_PROFILE_GC_MOVES))
 252                 sgen_gc_event_moves ();
 253         mono_profiler_gc_event (MONO_GC_EVENT_PRE_START_WORLD, generation);
 254         MONO_GC_WORLD_RESTART_BEGIN (generation);
 255         FOREACH_THREAD (info) {
 256                 info->stack_start = NULL;
 257 #ifdef USE_MONO_CTX
 258                 memset (&info->ctx, 0, sizeof (MonoContext));
 259 #else
 260                 memset (&info->regs, 0, sizeof (info->regs));
 261 #endif
 262         } END_FOREACH_THREAD
 263
 264         release_gc_locks ();
 265
 266         count = sgen_thread_handshake (FALSE);
 267         TV_GETTIME (end_sw);
 268         usec = TV_ELAPSED (stop_world_time, end_sw);
 269         max_pause_usec = MAX (usec, max_pause_usec);
 270         SGEN_LOG (2, "restarted %d thread(s) (pause time: %d usec, max: %d)", count, (int)usec, (int)max_pause_usec);
 271         mono_profiler_gc_event (MONO_GC_EVENT_POST_START_WORLD, generation);
 272         MONO_GC_WORLD_RESTART_END (generation);
 273
 274         mono_thread_hazardous_try_free_some ();
 275
 276         sgen_bridge_processing_finish (generation);
 277
 278         TV_GETTIME (end_bridge);
 279         bridge_usec = TV_ELAPSED (end_sw, end_bridge);
 280
 281         if (timing) {
 282                 timing [0].stw_time = usec;
 283                 timing [0].bridge_time = bridge_usec;
 284         }
 285
 286         sgen_memgov_collection_end (generation, timing, timing ? 2 : 0);
 287
 288         return count;
 289 }
 290
 291 #endif