7a8a19d1d9
Making sure committed memory is cleared when re-committed, even if using large pages. Reviewed-by: kbarrett, tschatzl
117 lines
4.2 KiB
C++
117 lines
4.2 KiB
C++
/*
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* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
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#define SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
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#include "memory/allocation.hpp"
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#include "memory/memRegion.hpp"
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#include "runtime/virtualspace.hpp"
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#include "utilities/bitMap.hpp"
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// Virtual space management helper for a virtual space with an OS page allocation
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// granularity.
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// (De-)Allocation requests are always OS page aligned by passing a page index
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// and multiples of pages.
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// The implementation gives an error when trying to commit or uncommit pages that
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// have already been committed or uncommitted.
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class G1PageBasedVirtualSpace VALUE_OBJ_CLASS_SPEC {
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friend class VMStructs;
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private:
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// Reserved area addresses.
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char* _low_boundary;
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char* _high_boundary;
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// The commit/uncommit granularity in bytes.
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size_t _page_size;
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// Bitmap used for verification of commit/uncommit operations.
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BitMap _committed;
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// Bitmap used to keep track of which pages are dirty or not for _special
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// spaces. This is needed because for those spaces the underlying memory
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// will only be zero filled the first time it is committed. Calls to commit
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// will use this bitmap and return whether or not the memory is zero filled.
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BitMap _dirty;
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// Indicates that the entire space has been committed and pinned in memory,
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// os::commit_memory() or os::uncommit_memory() have no function.
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bool _special;
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// Indicates whether the committed space should be executable.
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bool _executable;
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// Returns the index of the page which contains the given address.
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uintptr_t addr_to_page_index(char* addr) const;
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// Returns the address of the given page index.
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char* page_start(uintptr_t index);
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// Returns the byte size of the given number of pages.
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size_t byte_size_for_pages(size_t num);
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// Returns true if the entire area is backed by committed memory.
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bool is_area_committed(uintptr_t start, size_t size_in_pages) const;
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// Returns true if the entire area is not backed by committed memory.
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bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
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public:
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// Commit the given area of pages starting at start being size_in_pages large.
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// Returns true if the given area is zero filled upon completion.
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bool commit(uintptr_t start, size_t size_in_pages);
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// Uncommit the given area of pages starting at start being size_in_pages large.
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void uncommit(uintptr_t start, size_t size_in_pages);
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// Initialization
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G1PageBasedVirtualSpace();
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bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
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// Destruction
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~G1PageBasedVirtualSpace();
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// Amount of reserved memory.
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size_t reserved_size() const;
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// Memory used in this virtual space.
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size_t committed_size() const;
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// Memory left to use/expand in this virtual space.
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size_t uncommitted_size() const;
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bool contains(const void* p) const;
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MemRegion reserved() {
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MemRegion x((HeapWord*)_low_boundary, reserved_size() / HeapWordSize);
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return x;
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}
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void release();
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void check_for_contiguity() PRODUCT_RETURN;
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// Debugging
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void print_on(outputStream* out) PRODUCT_RETURN;
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void print();
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};
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#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1PAGEBASEDVIRTUALSPACE_HPP
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