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) && !defined(_MSC_VER)
  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 #ifdef _MSC_VER
  75         ARCH_STORE_REGS (cur_thread_regs);
  76         memcpy (&info->regs, cur_thread_regs, sizeof (info->regs));
  77 #else
  78         ARCH_STORE_REGS (reg_ptr);
  79         memcpy (&info->regs, reg_ptr, sizeof (info->regs));
  80 #endif
  81         if (mono_gc_get_gc_callbacks ()->thread_suspend_func)
  82                 mono_gc_get_gc_callbacks ()->thread_suspend_func (info->runtime_data, NULL, NULL);
  83 #endif
  84 }
  85
  86 static gboolean
  87 is_ip_in_managed_allocator (MonoDomain *domain, gpointer ip)
  88 {
  89         MonoJitInfo *ji;
  90
  91         if (!mono_thread_internal_current ())
  92                 /* Happens during thread attach */
  93                 return FALSE;
  94
  95         if (!ip || !domain)
  96                 return FALSE;
  97         if (!sgen_has_critical_method ())
  98                 return FALSE;
  99         ji = mono_jit_info_table_find (domain, ip);
 100         if (!ji)
 101                 return FALSE;
 102
 103         return sgen_is_critical_method (ji->method);
 104 }
 105
 106 static int
 107 restart_threads_until_none_in_managed_allocator (void)
 108 {
 109         SgenThreadInfo *info;
 110         int num_threads_died = 0;
 111         int sleep_duration = -1;
 112
 113         for (;;) {
 114                 int restart_count = 0, restarted_count = 0;
 115                 /* restart all threads that stopped in the
 116                    allocator */
 117                 FOREACH_THREAD_SAFE (info) {
 118                         gboolean result;
 119                         if (info->skip || info->gc_disabled || !info->joined_stw)
 120                                 continue;
 121                         if (!info->thread_is_dying && (!info->stack_start || info->in_critical_region || info->info.inside_critical_region ||
 122                                         is_ip_in_managed_allocator (info->stopped_domain, info->stopped_ip))) {
 123                                 binary_protocol_thread_restart ((gpointer)mono_thread_info_get_tid (info));
 124                                 SGEN_LOG (3, "thread %p resumed.", (void*) (size_t) info->info.native_handle);
 125                                 result = sgen_resume_thread (info);
 126                                 if (result) {
 127                                         ++restart_count;
 128                                 } else {
 129                                         info->skip = 1;
 130                                 }
 131                         } else {
 132                                 /* we set the stopped_ip to
 133                                    NULL for threads which
 134                                    we're not restarting so
 135                                    that we can easily identify
 136                                    the others */
 137                                 info->stopped_ip = NULL;
 138                                 info->stopped_domain = NULL;
 139                         }
 140                 } END_FOREACH_THREAD_SAFE
 141                 /* if no threads were restarted, we're done */
 142                 if (restart_count == 0)
 143                         break;
 144
 145                 /* wait for the threads to signal their restart */
 146                 sgen_wait_for_suspend_ack (restart_count);
 147
 148                 if (sleep_duration < 0) {
 149 #ifdef HOST_WIN32
 150                         SwitchToThread ();
 151 #else
 152                         sched_yield ();
 153 #endif
 154                         sleep_duration = 0;
 155                 } else {
 156                         g_usleep (sleep_duration);
 157                         sleep_duration += 10;
 158                 }
 159
 160                 /* stop them again */
 161                 FOREACH_THREAD (info) {
 162                         gboolean result;
 163                         if (info->skip || info->stopped_ip == NULL)
 164                                 continue;
 165                         result = sgen_suspend_thread (info);
 166
 167                         if (result) {
 168                                 ++restarted_count;
 169                         } else {
 170                                 info->skip = 1;
 171                         }
 172                 } END_FOREACH_THREAD
 173                 /* some threads might have died */
 174                 num_threads_died += restart_count - restarted_count;
 175                 /* wait for the threads to signal their suspension
 176                    again */
 177                 sgen_wait_for_suspend_ack (restarted_count);
 178         }
 179
 180         return num_threads_died;
 181 }
 182
 183 static void
 184 acquire_gc_locks (void)
 185 {
 186         LOCK_INTERRUPTION;
 187         mono_thread_info_suspend_lock ();
 188 }
 189
 190 static void
 191 release_gc_locks (void)
 192 {
 193         mono_thread_info_suspend_unlock ();
 194         UNLOCK_INTERRUPTION;
 195 }
 196
 197 static void
 198 stw_bridge_process (void)
 199 {
 200         sgen_bridge_processing_stw_step ();
 201 }
 202
 203 static void
 204 bridge_process (int generation)
 205 {
 206         sgen_bridge_processing_finish (generation);
 207 }
 208
 209 static TV_DECLARE (stop_world_time);
 210 static unsigned long max_pause_usec = 0;
 211
 212 /* LOCKING: assumes the GC lock is held */
 213 int
 214 sgen_stop_world (int generation)
 215 {
 216         int count, dead;
 217
 218         /*XXX this is the right stop, thought might not be the nicest place to put it*/
 219         sgen_process_togglerefs ();
 220
 221         mono_profiler_gc_event (MONO_GC_EVENT_PRE_STOP_WORLD, generation);
 222         MONO_GC_WORLD_STOP_BEGIN ();
 223         acquire_gc_locks ();
 224
 225         update_current_thread_stack (&count);
 226
 227         sgen_global_stop_count++;
 228         SGEN_LOG (3, "stopping world n %d from %p %p", sgen_global_stop_count, mono_thread_info_current (), (gpointer)mono_native_thread_id_get ());
 229         TV_GETTIME (stop_world_time);
 230         count = sgen_thread_handshake (TRUE);
 231         dead = restart_threads_until_none_in_managed_allocator ();
 232         if (count < dead)
 233                 g_error ("More threads have died (%d) that been initialy suspended %d", dead, count);
 234         count -= dead;
 235
 236         SGEN_LOG (3, "world stopped %d thread(s)", count);
 237         mono_profiler_gc_event (MONO_GC_EVENT_POST_STOP_WORLD, generation);
 238         MONO_GC_WORLD_STOP_END ();
 239
 240         sgen_memgov_collection_start (generation);
 241         sgen_bridge_reset_data ();
 242
 243         return count;
 244 }
 245
 246 /* LOCKING: assumes the GC lock is held */
 247 int
 248 sgen_restart_world (int generation, GGTimingInfo *timing)
 249 {
 250         int count;
 251         SgenThreadInfo *info;
 252         TV_DECLARE (end_sw);
 253         TV_DECLARE (end_bridge);
 254         unsigned long usec, bridge_usec;
 255
 256         /* notify the profiler of the leftovers */
 257         /* FIXME this is the wrong spot at we can STW for non collection reasons. */
 258         if (G_UNLIKELY (mono_profiler_events & MONO_PROFILE_GC_MOVES))
 259                 sgen_gc_event_moves ();
 260         mono_profiler_gc_event (MONO_GC_EVENT_PRE_START_WORLD, generation);
 261         MONO_GC_WORLD_RESTART_BEGIN (generation);
 262         FOREACH_THREAD (info) {
 263                 info->stack_start = NULL;
 264 #ifdef USE_MONO_CTX
 265                 memset (&info->ctx, 0, sizeof (MonoContext));
 266 #else
 267                 memset (&info->regs, 0, sizeof (info->regs));
 268 #endif
 269         } END_FOREACH_THREAD
 270
 271         stw_bridge_process ();
 272         release_gc_locks ();
 273
 274         count = sgen_thread_handshake (FALSE);
 275         TV_GETTIME (end_sw);
 276         usec = TV_ELAPSED (stop_world_time, end_sw);
 277         max_pause_usec = MAX (usec, max_pause_usec);
 278         SGEN_LOG (2, "restarted %d thread(s) (pause time: %d usec, max: %d)", count, (int)usec, (int)max_pause_usec);
 279         mono_profiler_gc_event (MONO_GC_EVENT_POST_START_WORLD, generation);
 280         MONO_GC_WORLD_RESTART_END (generation);
 281
 282         mono_thread_hazardous_try_free_some ();
 283
 284         bridge_process (generation);
 285
 286         TV_GETTIME (end_bridge);
 287         bridge_usec = TV_ELAPSED (end_sw, end_bridge);
 288
 289         if (timing) {
 290                 timing [0].stw_time = usec;
 291                 timing [0].bridge_time = bridge_usec;
 292         }
 293
 294         sgen_memgov_collection_end (generation, timing, timing ? 2 : 0);
 295
 296         return count;
 297 }
 298
 299 #endif