Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2007, 2011 Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "memory/allocation.inline.hpp"

 #include "memory/cardTableModRefBS.hpp"

 #include "memory/cardTableRS.hpp"

 #include "memory/sharedHeap.hpp"

 #include "memory/space.inline.hpp"

 #include "memory/universe.hpp"

 #include "runtime/java.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "runtime/virtualspace.hpp"

 void CardTableModRefBS::non_clean_card_iterate_parallel_work(Space* sp, MemRegion mr,

                                                              DirtyCardToOopClosure* dcto_cl,

                                                              ClearNoncleanCardWrapper* cl,

                                                              int n_threads) {

   assert(n_threads > 0, "Error: expected n_threads > 0");

   assert((n_threads == 1 && ParallelGCThreads == 0) ||

          n_threads <= (int)ParallelGCThreads,

          "# worker threads != # requested!");

   // Make sure the LNC array is valid for the space.

   jbyte**   lowest_non_clean;

   uintptr_t lowest_non_clean_base_chunk_index;

   size_t    lowest_non_clean_chunk_size;

   get_LNC_array_for_space(sp, lowest_non_clean,

                           lowest_non_clean_base_chunk_index,

                           lowest_non_clean_chunk_size);

   int n_strides = n_threads * StridesPerThread;

   SequentialSubTasksDone* pst = sp->par_seq_tasks();

   pst->set_n_threads(n_threads);

   pst->set_n_tasks(n_strides);

   int stride = 0;

   while (!pst->is_task_claimed(/* reference */ stride)) {

     process_stride(sp, mr, stride, n_strides, dcto_cl, cl,

                    lowest_non_clean,

                    lowest_non_clean_base_chunk_index,

                    lowest_non_clean_chunk_size);

   }

   if (pst->all_tasks_completed()) {

     // Clear lowest_non_clean array for next time.

     intptr_t first_chunk_index = addr_to_chunk_index(mr.start());

     uintptr_t last_chunk_index  = addr_to_chunk_index(mr.last());

     for (uintptr_t ch = first_chunk_index; ch <= last_chunk_index; ch++) {

       intptr_t ind = ch - lowest_non_clean_base_chunk_index;

       assert(0 <= ind && ind < (intptr_t)lowest_non_clean_chunk_size,

              "Bounds error");

       lowest_non_clean[ind] = NULL;

     }

   }

 }

 void

 CardTableModRefBS::

 process_stride(Space* sp,

                MemRegion used,

                jint stride, int n_strides,

                DirtyCardToOopClosure* dcto_cl,

                ClearNoncleanCardWrapper* cl,

                jbyte** lowest_non_clean,

                uintptr_t lowest_non_clean_base_chunk_index,

                size_t    lowest_non_clean_chunk_size) {

   // We don't have to go downwards here; it wouldn't help anyway,

   // because of parallelism.

   // Find the first card address of the first chunk in the stride that is

   // at least "bottom" of the used region.

   jbyte*    start_card  = byte_for(used.start());

   jbyte*    end_card    = byte_after(used.last());

   uintptr_t start_chunk = addr_to_chunk_index(used.start());

   uintptr_t start_chunk_stride_num = start_chunk % n_strides;

   jbyte* chunk_card_start;

   if ((uintptr_t)stride >= start_chunk_stride_num) {

     chunk_card_start = (jbyte*)(start_card +

                                 (stride - start_chunk_stride_num) *

                                 CardsPerStrideChunk);

   } else {

     // Go ahead to the next chunk group boundary, then to the requested stride.

     chunk_card_start = (jbyte*)(start_card +

                                 (n_strides - start_chunk_stride_num + stride) *

                                 CardsPerStrideChunk);

   }

   while (chunk_card_start < end_card) {

     // We don't have to go downwards here; it wouldn't help anyway,

     // because of parallelism.  (We take care with "min_done"; see below.)

     // Invariant: chunk_mr should be fully contained within the "used" region.

     jbyte*    chunk_card_end = chunk_card_start + CardsPerStrideChunk;

     MemRegion chunk_mr       = MemRegion(addr_for(chunk_card_start),

                                          chunk_card_end >= end_card ?

                                            used.end() : addr_for(chunk_card_end));

     assert(chunk_mr.word_size() > 0, "[chunk_card_start > used_end)");

     assert(used.contains(chunk_mr), "chunk_mr should be subset of used");

     // Process the chunk.

     process_chunk_boundaries(sp,

                              dcto_cl,

                              chunk_mr,

                              used,

                              lowest_non_clean,

                              lowest_non_clean_base_chunk_index,

                              lowest_non_clean_chunk_size);

     // We do not call the non_clean_card_iterate_serial() version because

     // we want to clear the cards, and the ClearNoncleanCardWrapper closure

     // itself does the work of finding contiguous dirty ranges of cards to

     // process (and clear).

     cl->do_MemRegion(chunk_mr);

     // Find the next chunk of the stride.

     chunk_card_start += CardsPerStrideChunk * n_strides;

   }

 }

 void

 CardTableModRefBS::

 process_chunk_boundaries(Space* sp,

                          DirtyCardToOopClosure* dcto_cl,

                          MemRegion chunk_mr,

                          MemRegion used,

                          jbyte** lowest_non_clean,

                          uintptr_t lowest_non_clean_base_chunk_index,

                          size_t    lowest_non_clean_chunk_size)

 {

   // We must worry about the chunk boundaries.

   // First, set our max_to_do:

   HeapWord* max_to_do = NULL;

   uintptr_t cur_chunk_index = addr_to_chunk_index(chunk_mr.start());

   cur_chunk_index           = cur_chunk_index - lowest_non_clean_base_chunk_index;

   if (chunk_mr.end() < used.end()) {

     // This is not the last chunk in the used region.  What is the last

     // object?

     HeapWord* last_block = sp->block_start(chunk_mr.end());

     assert(last_block <= chunk_mr.end(), "In case this property changes.");

     if (last_block == chunk_mr.end()

         || !sp->block_is_obj(last_block)) {

       max_to_do = chunk_mr.end();

     } else {

       // It is an object and starts before the end of the current chunk.

       // last_obj_card is the card corresponding to the start of the last object

       // in the chunk.  Note that the last object may not start in

       // the chunk.

       jbyte* last_obj_card = byte_for(last_block);

       if (!card_may_have_been_dirty(*last_obj_card)) {

         // The card containing the head is not dirty.  Any marks in

         // subsequent cards still in this chunk must have been made

         // precisely; we can cap processing at the end.

         max_to_do = chunk_mr.end();

       } else {

         // The last object must be considered dirty, and extends onto the

         // following chunk.  Look for a dirty card in that chunk that will

         // bound our processing.

         jbyte* limit_card = NULL;

         size_t last_block_size = sp->block_size(last_block);

         jbyte* last_card_of_last_obj =

           byte_for(last_block + last_block_size - 1);

         jbyte* first_card_of_next_chunk = byte_for(chunk_mr.end());

         // This search potentially goes a long distance looking

         // for the next card that will be scanned.  For example,

         // an object that is an array of primitives will not

         // have any cards covering regions interior to the array

         // that will need to be scanned. The scan can be terminated

         // at the last card of the next chunk.  That would leave

         // limit_card as NULL and would result in "max_to_do"

         // being set with the LNC value or with the end

         // of the last block.

         jbyte* last_card_of_next_chunk = first_card_of_next_chunk +

           CardsPerStrideChunk;

         assert(byte_for(chunk_mr.end()) - byte_for(chunk_mr.start())

           == CardsPerStrideChunk, "last card of next chunk may be wrong");

         jbyte* last_card_to_check = (jbyte*) MIN2(last_card_of_last_obj,

                                                   last_card_of_next_chunk);

         for (jbyte* cur = first_card_of_next_chunk;

              cur <= last_card_to_check; cur++) {

           if (card_will_be_scanned(*cur)) {

             limit_card = cur; break;

           }

         }

         assert(0 <= cur_chunk_index+1 &&

                cur_chunk_index+1 < lowest_non_clean_chunk_size,

                "Bounds error.");

         // LNC for the next chunk

         jbyte* lnc_card = lowest_non_clean[cur_chunk_index+1];

         if (limit_card == NULL) {

           limit_card = lnc_card;

         }

         if (limit_card != NULL) {

           if (lnc_card != NULL) {

             limit_card = (jbyte*)MIN2((intptr_t)limit_card,

                                       (intptr_t)lnc_card);

           }

           max_to_do = addr_for(limit_card);

         } else {

           max_to_do = last_block + last_block_size;

         }

       }

     }

     assert(max_to_do != NULL, "OOPS!");

   } else {

     max_to_do = used.end();

   }

   // Now we can set the closure we're using so it doesn't to beyond

   // max_to_do.

   dcto_cl->set_min_done(max_to_do);

 #ifndef PRODUCT

   dcto_cl->set_last_bottom(max_to_do);

 #endif

   // Now we set *our" lowest_non_clean entry.

   // Find the object that spans our boundary, if one exists.

   // Nothing to do on the first chunk.

   if (chunk_mr.start() > used.start()) {

     // first_block is the block possibly spanning the chunk start

     HeapWord* first_block = sp->block_start(chunk_mr.start());

     // Does the block span the start of the chunk and is it

     // an object?

     if (first_block < chunk_mr.start() &&

         sp->block_is_obj(first_block)) {

       jbyte* first_dirty_card = NULL;

       jbyte* last_card_of_first_obj =

           byte_for(first_block + sp->block_size(first_block) - 1);

       jbyte* first_card_of_cur_chunk = byte_for(chunk_mr.start());

       jbyte* last_card_of_cur_chunk = byte_for(chunk_mr.last());

       jbyte* last_card_to_check =

         (jbyte*) MIN2((intptr_t) last_card_of_cur_chunk,

                       (intptr_t) last_card_of_first_obj);

       for (jbyte* cur = first_card_of_cur_chunk;

            cur <= last_card_to_check; cur++) {

         if (card_will_be_scanned(*cur)) {

           first_dirty_card = cur; break;

         }

       }

       if (first_dirty_card != NULL) {

         assert(0 <= cur_chunk_index &&

                  cur_chunk_index < lowest_non_clean_chunk_size,

                "Bounds error.");

         lowest_non_clean[cur_chunk_index] = first_dirty_card;

       }

     }

   }

 }

 void

 CardTableModRefBS::

 get_LNC_array_for_space(Space* sp,

                         jbyte**& lowest_non_clean,

                         uintptr_t& lowest_non_clean_base_chunk_index,

                         size_t& lowest_non_clean_chunk_size) {

   int       i        = find_covering_region_containing(sp->bottom());

   MemRegion covered  = _covered[i];

   size_t    n_chunks = chunks_to_cover(covered);

   // Only the first thread to obtain the lock will resize the

   // LNC array for the covered region.  Any later expansion can't affect

   // the used_at_save_marks region.

   // (I observed a bug in which the first thread to execute this would

   // resize, and then it would cause "expand_and_allocates" that would

   // Increase the number of chunks in the covered region.  Then a second

   // thread would come and execute this, see that the size didn't match,

   // and free and allocate again.  So the first thread would be using a

   // freed "_lowest_non_clean" array.)

   // Do a dirty read here. If we pass the conditional then take the rare

   // event lock and do the read again in case some other thread had already

   // succeeded and done the resize.

   int cur_collection = Universe::heap()->total_collections();

   if (_last_LNC_resizing_collection[i] != cur_collection) {

     MutexLocker x(ParGCRareEvent_lock);

     if (_last_LNC_resizing_collection[i] != cur_collection) {

       if (_lowest_non_clean[i] == NULL ||

           n_chunks != _lowest_non_clean_chunk_size[i]) {

         // Should we delete the old?

         if (_lowest_non_clean[i] != NULL) {

           assert(n_chunks != _lowest_non_clean_chunk_size[i],

                  "logical consequence");

           FREE_C_HEAP_ARRAY(CardPtr, _lowest_non_clean[i]);

           _lowest_non_clean[i] = NULL;

         }

         // Now allocate a new one if necessary.

         if (_lowest_non_clean[i] == NULL) {

           _lowest_non_clean[i]                  = NEW_C_HEAP_ARRAY(CardPtr, n_chunks);

           _lowest_non_clean_chunk_size[i]       = n_chunks;

           _lowest_non_clean_base_chunk_index[i] = addr_to_chunk_index(covered.start());

           for (int j = 0; j < (int)n_chunks; j++)

             _lowest_non_clean[i][j] = NULL;

         }

       }

       _last_LNC_resizing_collection[i] = cur_collection;

     }

   }

   // In any case, now do the initialization.

   lowest_non_clean                  = _lowest_non_clean[i];

   lowest_non_clean_base_chunk_index = _lowest_non_clean_base_chunk_index[i];

   lowest_non_clean_chunk_size       = _lowest_non_clean_chunk_size[i];

 }