src/hotspot/share/gc/z/zWorkers.cpp

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  #include "precompiled.hpp"
  #include "gc/z/zGlobals.hpp"
  #include "gc/z/zTask.hpp"
  #include "gc/z/zThread.hpp"
  #include "gc/z/zWorkers.inline.hpp"
- #include "runtime/os.hpp"
  #include "runtime/mutexLocker.hpp"
  #include "runtime/safepoint.hpp"
  
- static uint calculate_nworkers_based_on_ncpus(double cpu_share_in_percent) {
-   return ceil(os::initial_active_processor_count() * cpu_share_in_percent / 100.0);
- }
- 
- static uint calculate_nworkers_based_on_heap_size(double reserve_share_in_percent) {
-   const int nworkers = (MaxHeapSize * (reserve_share_in_percent / 100.0)) / ZPageSizeSmall;
-   return MAX2(nworkers, 1);
- }
- 
- static uint calculate_nworkers(double cpu_share_in_percent) {
-   // Cap number of workers so that we don't use more than 2% of the max heap
-   // for the small page reserve. This is useful when using small heaps on
-   // large machines.
-   return MIN2(calculate_nworkers_based_on_ncpus(cpu_share_in_percent),
-               calculate_nworkers_based_on_heap_size(2.0));
- }
- 
- uint ZWorkers::calculate_nparallel() {
-   // Use 60% of the CPUs, rounded up. We would like to use as many threads as
-   // possible to increase parallelism. However, using a thread count that is
-   // close to the number of processors tends to lead to over-provisioning and
-   // scheduling latency issues. Using 60% of the active processors appears to
-   // be a fairly good balance.
-   return calculate_nworkers(60.0);
- }
- 
- uint ZWorkers::calculate_nconcurrent() {
-   // Use 12.5% of the CPUs, rounded up. The number of concurrent threads we
-   // would like to use heavily depends on the type of workload we are running.
-   // Using too many threads will have a negative impact on the application
-   // throughput, while using too few threads will prolong the GC-cycle and
-   // we then risk being out-run by the application. Using 12.5% of the active
-   // processors appears to be a fairly good balance.
-   return calculate_nworkers(12.5);
- }
- 
  class ZWorkersInitializeTask : public ZTask {
  private:
    const uint _nworkers;
    uint       _started;
    Monitor    _monitor;
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