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98 lines
3.6 KiB
C++
98 lines
3.6 KiB
C++
/*
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* Copyright (c) 2020, 2021, 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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#include "precompiled.hpp"
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#include "gc/shared/gc_globals.hpp"
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#include "gc/shared/pretouchTask.hpp"
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#include "logging/log.hpp"
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#include "runtime/atomic.hpp"
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#include "runtime/globals.hpp"
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#include "runtime/os.hpp"
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PretouchTask::PretouchTask(const char* task_name,
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char* start_address,
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char* end_address,
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size_t page_size,
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size_t chunk_size) :
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WorkerTask(task_name),
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_cur_addr(start_address),
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_end_addr(end_address),
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_page_size(page_size),
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_chunk_size(chunk_size) {
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assert(chunk_size >= page_size,
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"Chunk size " SIZE_FORMAT " is smaller than page size " SIZE_FORMAT,
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chunk_size, page_size);
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}
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size_t PretouchTask::chunk_size() {
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return PreTouchParallelChunkSize;
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}
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void PretouchTask::work(uint worker_id) {
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while (true) {
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char* cur_start = Atomic::load(&_cur_addr);
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char* cur_end = cur_start + MIN2(_chunk_size, pointer_delta(_end_addr, cur_start, 1));
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if (cur_start >= cur_end) {
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break;
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} else if (cur_start == Atomic::cmpxchg(&_cur_addr, cur_start, cur_end)) {
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os::pretouch_memory(cur_start, cur_end, _page_size);
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} // Else attempt to claim chunk failed, so try again.
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}
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}
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void PretouchTask::pretouch(const char* task_name, char* start_address, char* end_address,
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size_t page_size, WorkerThreads* pretouch_workers) {
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// Chunk size should be at least (unmodified) page size as using multiple threads
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// pretouch on a single page can decrease performance.
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size_t chunk_size = MAX2(PretouchTask::chunk_size(), page_size);
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#ifdef LINUX
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// When using THP we need to always pre-touch using small pages as the OS will
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// initially always use small pages.
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page_size = UseTransparentHugePages ? (size_t)os::vm_page_size() : page_size;
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#endif
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PretouchTask task(task_name, start_address, end_address, page_size, chunk_size);
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size_t total_bytes = pointer_delta(end_address, start_address, sizeof(char));
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if (total_bytes == 0) {
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return;
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}
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if (pretouch_workers != NULL) {
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size_t num_chunks = ((total_bytes - 1) / chunk_size) + 1;
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uint num_workers = (uint)MIN2(num_chunks, (size_t)pretouch_workers->max_workers());
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log_debug(gc, heap)("Running %s with %u workers for " SIZE_FORMAT " work units pre-touching " SIZE_FORMAT "B.",
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task.name(), num_workers, num_chunks, total_bytes);
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pretouch_workers->run_task(&task, num_workers);
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} else {
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log_debug(gc, heap)("Running %s pre-touching " SIZE_FORMAT "B.",
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task.name(), total_bytes);
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task.work(0);
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}
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}
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