hotspot/src/os_cpu/linux_x86/vm/threadLS_linux_x86.cpp
changeset 34633 2a6c7c7b30a7
parent 34632 bf3518bba285
child 34634 5b74061eb1bb
child 34635 2dab71a66523
child 34637 9b9298044d23
child 34639 cb73d3c05599
--- a/hotspot/src/os_cpu/linux_x86/vm/threadLS_linux_x86.cpp	Fri Dec 04 04:29:31 2015 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,98 +0,0 @@
-/*
- * Copyright (c) 1999, 2015, 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.
-// 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 Linux keeps the virtual memory mapping, but zaps the
-// physical memory page (i.e. similar to MADV_FREE on Solaris).
-
-#if !defined(AMD64) && !defined(MINIMIZE_RAM_USAGE)
-Thread* ThreadLocalStorage::_sp_map[1UL << (SP_BITLENGTH - PAGE_SHIFT)];
-
-void ThreadLocalStorage::generate_code_for_get_thread() {
-    // nothing we can do here for user-level thread
-}
-
-void ThreadLocalStorage::pd_init() {
-  assert(align_size_down(os::vm_page_size(), PAGE_SIZE) == os::vm_page_size(),
-         "page size must be multiple of PAGE_SIZE");
-}
-
-void ThreadLocalStorage::pd_set_thread(Thread* thread) {
-  os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
-  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;
-  }
-}
-#else
-
-void ThreadLocalStorage::generate_code_for_get_thread() {
-    // nothing we can do here for user-level thread
-}
-
-void ThreadLocalStorage::pd_init() {
-}
-
-void ThreadLocalStorage::pd_set_thread(Thread* thread) {
-  os::thread_local_storage_at_put(ThreadLocalStorage::thread_index(), thread);
-}
-#endif // !AMD64 && !MINIMIZE_RAM_USAGE