--- old/src/os_cpu/bsd_x86/vm/threadLS_bsd_x86.cpp 2015-11-19 01:05:10.822752831 -0500 +++ /dev/null 2015-09-28 11:47:54.419050997 -0400 @@ -1,92 +0,0 @@ -/* - * Copyright (c) 1999, 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 "runtime/thread.inline.hpp" -#include "runtime/threadLocalStorage.hpp" - -// Map stack pointer (%esp) to thread pointer for faster TLS access -// -// Here we use a flat table for better performance. Getting current thread -// is down to one memory access (read _sp_map[%esp>>12]) in generated code -// and two in runtime code (-fPIC code needs an extra load for _sp_map). -// -// This code assumes stack page is not shared by different threads. It works -// in 32-bit VM when page size is 4K (or a multiple of 4K, if that matters). -// -// Notice that _sp_map is allocated in the bss segment, which is ZFOD -// (zero-fill-on-demand). While it reserves 4M address space upfront, -// actual memory pages are committed on demand. -// -// If an application creates and destroys a lot of threads, usually the -// stack space freed by a thread will soon get reused by new thread -// (this is especially true in NPTL or BsdThreads in fixed-stack mode). -// No memory page in _sp_map is wasted. -// -// However, it's still possible that we might end up populating & -// committing a large fraction of the 4M table over time, but the actual -// amount of live data in the table could be quite small. The max wastage -// is less than 4M bytes. If it becomes an issue, we could use madvise() -// with MADV_DONTNEED to reclaim unused (i.e. all-zero) pages in _sp_map. -// MADV_DONTNEED on Bsd keeps the virtual memory mapping, but zaps the -// physical memory page (i.e. similar to MADV_FREE on Solaris). - -#ifndef AMD64 -Thread* ThreadLocalStorage::_sp_map[1UL << (SP_BITLENGTH - PAGE_SHIFT)]; -#endif // !AMD64 - -void ThreadLocalStorage::generate_code_for_get_thread() { - // nothing we can do here for user-level thread -} - -void ThreadLocalStorage::pd_init() { -#ifndef AMD64 - assert(align_size_down(os::vm_page_size(), PAGE_SIZE) == os::vm_page_size(), - "page size must be multiple of PAGE_SIZE"); -#endif // !AMD64 -} - -void ThreadLocalStorage::pd_set_thread(Thread* thread) { - os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread); - -#ifndef AMD64 - address stack_top = os::current_stack_base(); - size_t stack_size = os::current_stack_size(); - - for (address p = stack_top - stack_size; p < stack_top; p += PAGE_SIZE) { - // pd_set_thread() is called with non-NULL value when a new thread is - // created/attached, or with NULL value when a thread is about to exit. - // If both "thread" and the corresponding _sp_map[] entry are non-NULL, - // they should have the same value. Otherwise it might indicate that the - // stack page is shared by multiple threads. However, a more likely cause - // for this assertion to fail is that an attached thread exited without - // detaching itself from VM, which is a program error and could cause VM - // to crash. - assert(thread == NULL || _sp_map[(uintptr_t)p >> PAGE_SHIFT] == NULL || - thread == _sp_map[(uintptr_t)p >> PAGE_SHIFT], - "thread exited without detaching from VM??"); - _sp_map[(uintptr_t)p >> PAGE_SHIFT] = thread; - } -#endif // !AMD64 -}