Mercurial > hg > truffle
view src/share/vm/gc_implementation/g1/heapRegionSeq.cpp @ 2066:02895c6a2f82
7007769: VM crashes with SIGBUS writing PerfData if tmp space is full
Summary: Fill perfdata file with zeros to verify available disk space
Reviewed-by: coleenp, kamg
author | bobv |
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date | Mon, 20 Dec 2010 14:30:24 -0500 |
parents | f95d63e2154a |
children | 2250ee17e258 |
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/* * Copyright (c) 2001, 2010, 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 "gc_implementation/g1/g1CollectedHeap.inline.hpp" #include "gc_implementation/g1/heapRegionSeq.hpp" #include "memory/allocation.hpp" // Local to this file. static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) { if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1; else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1; else if (*hr1p == *hr2p) return 0; else { assert(false, "We should never compare distinct overlapping regions."); } return 0; } HeapRegionSeq::HeapRegionSeq(const size_t max_size) : _alloc_search_start(0), // The line below is the worst bit of C++ hackery I've ever written // (Detlefs, 11/23). You should think of it as equivalent to // "_regions(100, true)": initialize the growable array and inform it // that it should allocate its elem array(s) on the C heap. // // The first argument, however, is actually a comma expression // (set_allocation_type(this, C_HEAP), 100). The purpose of the // set_allocation_type() call is to replace the default allocation // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will // allow to pass the assert in GenericGrowableArray() which checks // that a growable array object must be on C heap if elements are. // // Note: containing object is allocated on C heap since it is CHeapObj. // _regions((ResourceObj::set_allocation_type((address)&_regions, ResourceObj::C_HEAP), (int)max_size), true), _next_rr_candidate(0), _seq_bottom(NULL) {} // Private methods. HeapWord* HeapRegionSeq::alloc_obj_from_region_index(int ind, size_t word_size) { assert(G1CollectedHeap::isHumongous(word_size), "Allocation size should be humongous"); int cur = ind; int first = cur; size_t sumSizes = 0; while (cur < _regions.length() && sumSizes < word_size) { // Loop invariant: // For all i in [first, cur): // _regions.at(i)->is_empty() // && _regions.at(i) is contiguous with its predecessor, if any // && sumSizes is the sum of the sizes of the regions in the interval // [first, cur) HeapRegion* curhr = _regions.at(cur); if (curhr->is_empty() && (first == cur || (_regions.at(cur-1)->end() == curhr->bottom()))) { sumSizes += curhr->capacity() / HeapWordSize; } else { first = cur + 1; sumSizes = 0; } cur++; } if (sumSizes >= word_size) { _alloc_search_start = cur; // We need to initialize the region(s) we just discovered. This is // a bit tricky given that it can happen concurrently with // refinement threads refining cards on these regions and // potentially wanting to refine the BOT as they are scanning // those cards (this can happen shortly after a cleanup; see CR // 6991377). So we have to set up the region(s) carefully and in // a specific order. // Currently, allocs_are_zero_filled() returns false. The zero // filling infrastructure will be going away soon (see CR 6977804). // So no need to do anything else here. bool zf = G1CollectedHeap::heap()->allocs_are_zero_filled(); assert(!zf, "not supported"); // This will be the "starts humongous" region. HeapRegion* first_hr = _regions.at(first); { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); first_hr->set_zero_fill_allocated(); } // The header of the new object will be placed at the bottom of // the first region. HeapWord* new_obj = first_hr->bottom(); // This will be the new end of the first region in the series that // should also match the end of the last region in the seriers. // (Note: sumSizes = "region size" x "number of regions we found"). HeapWord* new_end = new_obj + sumSizes; // This will be the new top of the first region that will reflect // this allocation. HeapWord* new_top = new_obj + word_size; // First, we need to zero the header of the space that we will be // allocating. When we update top further down, some refinement // threads might try to scan the region. By zeroing the header we // ensure that any thread that will try to scan the region will // come across the zero klass word and bail out. // // NOTE: It would not have been correct to have used // CollectedHeap::fill_with_object() and make the space look like // an int array. The thread that is doing the allocation will // later update the object header to a potentially different array // type and, for a very short period of time, the klass and length // fields will be inconsistent. This could cause a refinement // thread to calculate the object size incorrectly. Copy::fill_to_words(new_obj, oopDesc::header_size(), 0); // We will set up the first region as "starts humongous". This // will also update the BOT covering all the regions to reflect // that there is a single object that starts at the bottom of the // first region. first_hr->set_startsHumongous(new_end); // Then, if there are any, we will set up the "continues // humongous" regions. HeapRegion* hr = NULL; for (int i = first + 1; i < cur; ++i) { hr = _regions.at(i); { MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); hr->set_zero_fill_allocated(); } hr->set_continuesHumongous(first_hr); } // If we have "continues humongous" regions (hr != NULL), then the // end of the last one should match new_end. assert(hr == NULL || hr->end() == new_end, "sanity"); // Up to this point no concurrent thread would have been able to // do any scanning on any region in this series. All the top // fields still point to bottom, so the intersection between // [bottom,top] and [card_start,card_end] will be empty. Before we // update the top fields, we'll do a storestore to make sure that // no thread sees the update to top before the zeroing of the // object header and the BOT initialization. OrderAccess::storestore(); // Now that the BOT and the object header have been initialized, // we can update top of the "starts humongous" region. assert(first_hr->bottom() < new_top && new_top <= first_hr->end(), "new_top should be in this region"); first_hr->set_top(new_top); // Now, we will update the top fields of the "continues humongous" // regions. The reason we need to do this is that, otherwise, // these regions would look empty and this will confuse parts of // G1. For example, the code that looks for a consecutive number // of empty regions will consider them empty and try to // re-allocate them. We can extend is_empty() to also include // !continuesHumongous(), but it is easier to just update the top // fields here. hr = NULL; for (int i = first + 1; i < cur; ++i) { hr = _regions.at(i); if ((i + 1) == cur) { // last continues humongous region assert(hr->bottom() < new_top && new_top <= hr->end(), "new_top should fall on this region"); hr->set_top(new_top); } else { // not last one assert(new_top > hr->end(), "new_top should be above this region"); hr->set_top(hr->end()); } } // If we have continues humongous regions (hr != NULL), then the // end of the last one should match new_end and its top should // match new_top. assert(hr == NULL || (hr->end() == new_end && hr->top() == new_top), "sanity"); return new_obj; } else { // If we started from the beginning, we want to know why we can't alloc. return NULL; } } void HeapRegionSeq::print_empty_runs() { int empty_run = 0; int n_empty = 0; int empty_run_start; for (int i = 0; i < _regions.length(); i++) { HeapRegion* r = _regions.at(i); if (r->continuesHumongous()) continue; if (r->is_empty()) { assert(!r->isHumongous(), "H regions should not be empty."); if (empty_run == 0) empty_run_start = i; empty_run++; n_empty++; } else { if (empty_run > 0) { gclog_or_tty->print(" %d:%d", empty_run_start, empty_run); empty_run = 0; } } } if (empty_run > 0) { gclog_or_tty->print(" %d:%d", empty_run_start, empty_run); } gclog_or_tty->print_cr(" [tot = %d]", n_empty); } int HeapRegionSeq::find(HeapRegion* hr) { // FIXME: optimized for adjacent regions of fixed size. int ind = hr->hrs_index(); if (ind != -1) { assert(_regions.at(ind) == hr, "Mismatch"); } return ind; } // Public methods. void HeapRegionSeq::insert(HeapRegion* hr) { assert(!_regions.is_full(), "Too many elements in HeapRegionSeq"); if (_regions.length() == 0 || _regions.top()->end() <= hr->bottom()) { hr->set_hrs_index(_regions.length()); _regions.append(hr); } else { _regions.append(hr); _regions.sort(orderRegions); for (int i = 0; i < _regions.length(); i++) { _regions.at(i)->set_hrs_index(i); } } char* bot = (char*)_regions.at(0)->bottom(); if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot; } size_t HeapRegionSeq::length() { return _regions.length(); } size_t HeapRegionSeq::free_suffix() { size_t res = 0; int first = _regions.length() - 1; int cur = first; while (cur >= 0 && (_regions.at(cur)->is_empty() && (first == cur || (_regions.at(cur+1)->bottom() == _regions.at(cur)->end())))) { res++; cur--; } return res; } HeapWord* HeapRegionSeq::obj_allocate(size_t word_size) { int cur = _alloc_search_start; // Make sure "cur" is a valid index. assert(cur >= 0, "Invariant."); HeapWord* res = alloc_obj_from_region_index(cur, word_size); if (res == NULL) res = alloc_obj_from_region_index(0, word_size); return res; } void HeapRegionSeq::iterate(HeapRegionClosure* blk) { iterate_from((HeapRegion*)NULL, blk); } // The first argument r is the heap region at which iteration begins. // This operation runs fastest when r is NULL, or the heap region for // which a HeapRegionClosure most recently returned true, or the // heap region immediately to its right in the sequence. In all // other cases a linear search is required to find the index of r. void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) { // :::: FIXME :::: // Static cache value is bad, especially when we start doing parallel // remembered set update. For now just don't cache anything (the // code in the def'd out blocks). #if 0 static int cached_j = 0; #endif int len = _regions.length(); int j = 0; // Find the index of r. if (r != NULL) { #if 0 assert(cached_j >= 0, "Invariant."); if ((cached_j < len) && (r == _regions.at(cached_j))) { j = cached_j; } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) { j = cached_j + 1; } else { j = find(r); #endif if (j < 0) { j = 0; } #if 0 } #endif } int i; for (i = j; i < len; i += 1) { int res = blk->doHeapRegion(_regions.at(i)); if (res) { #if 0 cached_j = i; #endif blk->incomplete(); return; } } for (i = 0; i < j; i += 1) { int res = blk->doHeapRegion(_regions.at(i)); if (res) { #if 0 cached_j = i; #endif blk->incomplete(); return; } } } void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) { int len = _regions.length(); int i; for (i = idx; i < len; i++) { if (blk->doHeapRegion(_regions.at(i))) { blk->incomplete(); return; } } for (i = 0; i < idx; i++) { if (blk->doHeapRegion(_regions.at(i))) { blk->incomplete(); return; } } } MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes, size_t& num_regions_deleted) { assert(shrink_bytes % os::vm_page_size() == 0, "unaligned"); assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned"); if (_regions.length() == 0) { num_regions_deleted = 0; return MemRegion(); } int j = _regions.length() - 1; HeapWord* end = _regions.at(j)->end(); HeapWord* last_start = end; while (j >= 0 && shrink_bytes > 0) { HeapRegion* cur = _regions.at(j); // We have to leave humongous regions where they are, // and work around them. if (cur->isHumongous()) { return MemRegion(last_start, end); } assert(cur == _regions.top(), "Should be top"); if (!cur->is_empty()) break; cur->reset_zero_fill(); shrink_bytes -= cur->capacity(); num_regions_deleted++; _regions.pop(); last_start = cur->bottom(); // We need to delete these somehow, but can't currently do so here: if // we do, the ZF thread may still access the deleted region. We'll // leave this here as a reminder that we have to do something about // this. // delete cur; j--; } return MemRegion(last_start, end); } class PrintHeapRegionClosure : public HeapRegionClosure { public: bool doHeapRegion(HeapRegion* r) { gclog_or_tty->print(PTR_FORMAT ":", r); r->print(); return false; } }; void HeapRegionSeq::print() { PrintHeapRegionClosure cl; iterate(&cl); }