src/hotspot/share/gc/shared/taskTerminator.hpp

*** 20,31 ****
   * 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.
   *
   */
! #ifndef SHARE_GC_SHARED_OWSTTASKTERMINATOR_HPP
! #define SHARE_GC_SHARED_OWSTTASKTERMINATOR_HPP
  
  #include "memory/allocation.hpp"
  #include "runtime/mutex.hpp"
  #include "runtime/thread.hpp"
  
--- 20,31 ----
   * 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.
   *
   */
! #ifndef SHARE_GC_SHARED_TASKTERMINATOR_HPP
! #define SHARE_GC_SHARED_TASKTERMINATOR_HPP
  
  #include "memory/allocation.hpp"
  #include "runtime/mutex.hpp"
  #include "runtime/thread.hpp"
  
*** 34,58 ****
  
  class TaskQueueSetSuper;
  class TerminatorTerminator;
  
  /*
!  * Provides a task termination protocol. OWST stands for Optimized Work Stealing Threads
   *
!  * This is an enhanced implementation of Google's work stealing task termination
!  * protocol, which is described in the paper:
   * "Wessam Hassanein. 2016. Understanding and improving JVM GC work
   * stealing at the data center scale. In Proceedings of the 2016 ACM
   * SIGPLAN International Symposium on Memory Management (ISMM 2016). ACM,
   * New York, NY, USA, 46-54. DOI: https://doi.org/10.1145/2926697.2926706"
   *
   * Instead of a dedicated spin-master, our implementation will let spin-master relinquish
   * the role before it goes to sleep/wait, allowing newly arrived threads to compete for the role.
   * The intention of above enhancement is to reduce spin-master's latency on detecting new tasks
   * for stealing and termination condition.
   */
! class OWSTTaskTerminator : public CHeapObj<mtGC> {
    uint _n_threads;
    TaskQueueSetSuper* _queue_set;
  
    DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0);
    volatile uint _offered_termination;
--- 34,60 ----
  
  class TaskQueueSetSuper;
  class TerminatorTerminator;
  
  /*
!  * Provides a task termination protocol.
   *
!  * This is an enhanced implementation of Google's OWST work stealing task termination
!  * protocol (OWST stands for Optimized Work Stealing Threads).
!  * 
!  * It is described in the paper:
   * "Wessam Hassanein. 2016. Understanding and improving JVM GC work
   * stealing at the data center scale. In Proceedings of the 2016 ACM
   * SIGPLAN International Symposium on Memory Management (ISMM 2016). ACM,
   * New York, NY, USA, 46-54. DOI: https://doi.org/10.1145/2926697.2926706"
   *
   * Instead of a dedicated spin-master, our implementation will let spin-master relinquish
   * the role before it goes to sleep/wait, allowing newly arrived threads to compete for the role.
   * The intention of above enhancement is to reduce spin-master's latency on detecting new tasks
   * for stealing and termination condition.
   */
! class TaskTerminator : public CHeapObj<mtGC> {
    uint _n_threads;
    TaskQueueSetSuper* _queue_set;
  
    DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, 0);
    volatile uint _offered_termination;
*** 79,93 ****
  
    // Perform spin-master task.
    // Return true if termination condition is detected, otherwise return false
    bool do_spin_master_work(TerminatorTerminator* terminator);
  
!   NONCOPYABLE(OWSTTaskTerminator);
  
  public:
!   OWSTTaskTerminator(uint n_threads, TaskQueueSetSuper* queue_set);
!   ~OWSTTaskTerminator();
  
    // The current thread has no work, and is ready to terminate if everyone
    // else is.  If returns "true", all threads are terminated.  If returns
    // "false", available work has been observed in one of the task queues,
    // so the global task is not complete.
--- 81,95 ----
  
    // Perform spin-master task.
    // Return true if termination condition is detected, otherwise return false
    bool do_spin_master_work(TerminatorTerminator* terminator);
  
!   NONCOPYABLE(TaskTerminator);
  
  public:
!   TaskTerminator(uint n_threads, TaskQueueSetSuper* queue_set);
!   ~TaskTerminator();
  
    // The current thread has no work, and is ready to terminate if everyone
    // else is.  If returns "true", all threads are terminated.  If returns
    // "false", available work has been observed in one of the task queues,
    // so the global task is not complete.
*** 115,121 ****
    static uint total_peeks() { return _total_peeks; }
    static void print_termination_counts();
  #endif
  };
  
! 
! #endif // SHARE_GC_SHARED_OWSTTASKTERMINATOR_HPP
--- 117,122 ----
    static uint total_peeks() { return _total_peeks; }
    static void print_termination_counts();
  #endif
  };
  
! #endif // SHARE_GC_SHARED_TASKTERMINATOR_HPP