Mercurial > hg > truffle
annotate src/os_cpu/linux_x86/vm/threadLS_linux_x86.cpp @ 21947:9f70fc90169d
Truffle: remove expensive assertion
| author | Andreas Woess <andreas.woess@oracle.com> |
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| date | Wed, 17 Jun 2015 04:09:30 +0200 |
| parents | f34d701e952e |
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| rev | line source |
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| 0 | 1 /* |
| 1972 | 2 * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved. |
| 0 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 0 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
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26 #include "runtime/thread.inline.hpp" |
| 1972 | 27 #include "runtime/threadLocalStorage.hpp" |
| 0 | 28 |
| 29 // Map stack pointer (%esp) to thread pointer for faster TLS access | |
| 30 // | |
| 31 // Here we use a flat table for better performance. Getting current thread | |
| 32 // is down to one memory access (read _sp_map[%esp>>12]) in generated code | |
| 33 // and two in runtime code (-fPIC code needs an extra load for _sp_map). | |
| 34 // | |
| 35 // This code assumes stack page is not shared by different threads. It works | |
| 36 // in 32-bit VM when page size is 4K (or a multiple of 4K, if that matters). | |
| 37 // | |
| 38 // Notice that _sp_map is allocated in the bss segment, which is ZFOD | |
| 39 // (zero-fill-on-demand). While it reserves 4M address space upfront, | |
| 40 // actual memory pages are committed on demand. | |
| 41 // | |
| 42 // If an application creates and destroys a lot of threads, usually the | |
| 43 // stack space freed by a thread will soon get reused by new thread | |
| 44 // (this is especially true in NPTL or LinuxThreads in fixed-stack mode). | |
| 45 // No memory page in _sp_map is wasted. | |
| 46 // | |
| 47 // However, it's still possible that we might end up populating & | |
| 48 // committing a large fraction of the 4M table over time, but the actual | |
| 49 // amount of live data in the table could be quite small. The max wastage | |
| 50 // is less than 4M bytes. If it becomes an issue, we could use madvise() | |
| 51 // with MADV_DONTNEED to reclaim unused (i.e. all-zero) pages in _sp_map. | |
| 52 // MADV_DONTNEED on Linux keeps the virtual memory mapping, but zaps the | |
| 53 // physical memory page (i.e. similar to MADV_FREE on Solaris). | |
| 54 | |
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55 #if !defined(AMD64) && !defined(MINIMIZE_RAM_USAGE) |
| 0 | 56 Thread* ThreadLocalStorage::_sp_map[1UL << (SP_BITLENGTH - PAGE_SHIFT)]; |
| 57 | |
| 58 void ThreadLocalStorage::generate_code_for_get_thread() { | |
| 59 // nothing we can do here for user-level thread | |
| 60 } | |
| 61 | |
| 62 void ThreadLocalStorage::pd_init() { | |
| 63 assert(align_size_down(os::vm_page_size(), PAGE_SIZE) == os::vm_page_size(), | |
| 64 "page size must be multiple of PAGE_SIZE"); | |
| 65 } | |
| 66 | |
| 67 void ThreadLocalStorage::pd_set_thread(Thread* thread) { | |
| 68 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); | |
| 69 address stack_top = os::current_stack_base(); | |
| 70 size_t stack_size = os::current_stack_size(); | |
| 71 | |
| 72 for (address p = stack_top - stack_size; p < stack_top; p += PAGE_SIZE) { | |
| 73 // pd_set_thread() is called with non-NULL value when a new thread is | |
| 74 // created/attached, or with NULL value when a thread is about to exit. | |
| 75 // If both "thread" and the corresponding _sp_map[] entry are non-NULL, | |
| 76 // they should have the same value. Otherwise it might indicate that the | |
| 77 // stack page is shared by multiple threads. However, a more likely cause | |
| 78 // for this assertion to fail is that an attached thread exited without | |
| 79 // detaching itself from VM, which is a program error and could cause VM | |
| 80 // to crash. | |
| 81 assert(thread == NULL || _sp_map[(uintptr_t)p >> PAGE_SHIFT] == NULL || | |
| 82 thread == _sp_map[(uintptr_t)p >> PAGE_SHIFT], | |
| 83 "thread exited without detaching from VM??"); | |
| 84 _sp_map[(uintptr_t)p >> PAGE_SHIFT] = thread; | |
| 85 } | |
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86 } |
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87 #else |
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88 |
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89 void ThreadLocalStorage::generate_code_for_get_thread() { |
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90 // nothing we can do here for user-level thread |
| 0 | 91 } |
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92 |
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93 void ThreadLocalStorage::pd_init() { |
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94 } |
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95 |
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96 void ThreadLocalStorage::pd_set_thread(Thread* thread) { |
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97 os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); |
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98 } |
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99 #endif // !AMD64 && !MINIMIZE_RAM_USAGE |