[Lldb-commits] [PATCH] D87765: [llvm][lldb] Add optimal ThreadPool concurrency

[Dmitry Antipov via Phabricator via lldb-commits]

dmantipov created this revision.
dmantipov added a reviewer: labath.
Herald added subscribers: llvm-commits, lldb-commits, arphaman.
Herald added projects: LLDB, LLVM.
dmantipov requested review of this revision.
Herald added a subscriber: JDevlieghere.

Add an optimal thread strategy to execute specified amount of tasks. This strategy should prevent us from creating too many threads if we occasionaly have an unexpectedly small amount of tasks.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87765

Files:
  lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
  llvm/include/llvm/Support/Threading.h


Index: llvm/include/llvm/Support/Threading.h
===================================================================
--- llvm/include/llvm/Support/Threading.h
+++ llvm/include/llvm/Support/Threading.h
@@ -210,7 +210,7 @@
     return heavyweight_hardware_concurrency();
   }
 
-  /// Returns a default thread strategy where all available hardware ressources
+  /// Returns a default thread strategy where all available hardware resources
   /// are to be used, except for those initially excluded by an affinity mask.
   /// This function takes affinity into consideration. Returns 1 when LLVM is
   /// configured with LLVM_ENABLE_THREADS=OFF.
@@ -220,6 +220,16 @@
     return S;
   }
 
+  /// Returns an optimal thread strategy to execute specified amount of tasks.
+  /// This strategy should prevent us from creating too many threads if we
+  /// occasionaly have an unexpectedly small amount of tasks.
+  inline ThreadPoolStrategy optimal_concurrency(unsigned TaskCount = 0) {
+    ThreadPoolStrategy S;
+    S.Limit = true;
+    S.ThreadsRequested = TaskCount;
+    return S;
+  }
+
   /// Return the current thread id, as used in various OS system calls.
   /// Note that not all platforms guarantee that the value returned will be
   /// unique across the entire system, so portable code should not assume
Index: lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
@@ -73,7 +73,7 @@
 
   // Share one thread pool across operations to avoid the overhead of
   // recreating the threads.
-  llvm::ThreadPool pool;
+  llvm::ThreadPool pool(llvm::optimal_concurrency(units_to_index.size()));
 
   // Create a task runner that extracts dies for each DWARF unit in a
   // separate thread.


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