Adding enable_elasticity option to pool configuration

- fixing performance problem related to get_used_processing_units() for non-elastic pools
STEllAR-GROUP · Nov 21, 2017 · b12dd16 · b12dd16
1 parent e7e1ee2
commit b12dd16
Show file tree

Hide file tree

Showing 3 changed files with 25 additions and 1 deletion.
diff --git a/hpx/runtime/threads/detail/scheduled_thread_pool_impl.hpp b/hpx/runtime/threads/detail/scheduled_thread_pool_impl.hpp
@@ -1347,6 +1347,14 @@ namespace hpx { namespace threads { namespace detail
         std::size_t virt_core, std::size_t thread_num,
         std::shared_ptr<compat::barrier> startup, error_code& ec)
     {
+        if (!(mode_ & enable_elasticity))
+        {
+            HPX_THROW_EXCEPTION(invalid_status,
+                "scheduled_thread_pool<Scheduler>::add_processing_unit",
+                "this thread pool does not support dynamicly adding processing "
+                    "units");
+        }
+
         resource::get_partitioner().assign_pu(id_.name(), virt_core);
 
         std::unique_lock<pu_mutex_type> l(used_processing_units_mtx_);
@@ -1397,6 +1405,14 @@ namespace hpx { namespace threads { namespace detail
     void scheduled_thread_pool<Scheduler>::remove_processing_unit(
         std::size_t virt_core, error_code& ec)
     {
+        if (!(mode_ & enable_elasticity))
+        {
+            HPX_THROW_EXCEPTION(invalid_status,
+                "scheduled_thread_pool<Scheduler>::remove_processing_unit",
+                "this thread pool does not support dynamicly removing "
+                    "processing units");
+        }
+
         compat::thread t;
 
         // inform the scheduler to stop the virtual core

diff --git a/hpx/runtime/threads/policies/scheduler_mode.hpp b/hpx/runtime/threads/policies/scheduler_mode.hpp
@@ -14,7 +14,8 @@ namespace hpx { namespace threads { namespace policies
         do_background_work = 0x1,
         reduce_thread_priority = 0x02,
         delay_exit = 0x04,
-        fast_idle_mode = 0x08
+        fast_idle_mode = 0x08,
+        enable_elasticity = 0x10
     };
 }}}
 

diff --git a/src/runtime/threads/detail/thread_pool_base.cpp b/src/runtime/threads/detail/thread_pool_base.cpp
@@ -47,6 +47,13 @@ namespace hpx { namespace threads { namespace detail
     ///////////////////////////////////////////////////////////////////////////
     mask_cref_type thread_pool_base::get_used_processing_units() const
     {
+        if (!(mode_ & threads::policies::enable_elasticity))
+        {
+            return used_processing_units_;
+        }
+
+        // FIXME: this is broken as the function returns a reference allowing
+        // to access the value of the mask without it being guarded.
         std::lock_guard<pu_mutex_type> l(used_processing_units_mtx_);
         return used_processing_units_;
     }