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

Dmitry Antipov via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Wed Sep 23 09:44:55 PDT 2020

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG68358081585b: Add optimal thread strategy (authored by dmantipov).

  rG LLVM Github Monorepo




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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