src/hotspot/share/gc/shared/partialArrayTaskStepper.hpp - master - githubmirror/panama-vector

src/hotspot/share/gc/shared/partialArrayTaskStepper.hpp
75 строк3 KB
Ivan Walulya
8382084: Use dynamic chunk sizes in PartialArraySplitter
14 апр 2026, 13:51
14 апр 2026, 13:51540c714
/*
 * Copyright (c) 2020, 2026, 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
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 */

#ifndef SHARE_GC_SHARED_PARTIALARRAYTASKSTEPPER_HPP
#define SHARE_GC_SHARED_PARTIALARRAYTASKSTEPPER_HPP

#include "oops/arrayOop.hpp"
#include "runtime/atomic.hpp"
#include "utilities/globalDefinitions.hpp"

class PartialArrayState;

// Helper for partial array chunking tasks.
//
// When an array is large, we want to split it up into chunks that can be
// processed in parallel.  Each task (implicitly) represents such a chunk.  We
// can enqueue multiple tasks at the same time.  We want to enqueue enough
// tasks to benefit from the available parallelism, while not so many as to
// substantially expand the task queues.
class PartialArrayTaskStepper {
public:
  PartialArrayTaskStepper(uint n_workers);

  struct Step {
    size_t _index;              // Array index for the step.
    uint _ncreate;              // Number of new tasks to create.
  };

  // Called with the length of the array to be processed and chunk size.
  // Returns a Step with _index being the end of the initial chunk, which the
  // caller should process.  This is also the starting index for the next chunk to process.
  // The _ncreate is the number of tasks to enqueue to continue processing the
  // array.  If _ncreate is zero then _index will be length.
  inline Step start(size_t length, size_t chunk_size) const;

  // Atomically increment state's index by chunk_size() to claim the next
  // chunk.  Returns a Step with _index being the starting index of the
  // claimed chunk and _ncreate being the number of additional partial tasks
  // to enqueue.
  inline Step next(PartialArrayState* state) const;

  class TestSupport;            // For unit tests

private:
  // Limit on the number of partial array tasks to create for a given array.
  uint _task_limit;
  // Maximum number of new tasks to create when processing an existing task.
  uint _task_fanout;

  // For unit tests.
  inline Step next_impl(size_t length, size_t chunk_size, Atomic<size_t>* index_addr) const;
};

#endif // SHARE_GC_SHARED_PARTIALARRAYTASKSTEPPER_HPP