Add -sample-profiling-freq flag

Summary: This flag allows us to set the profiling frequency in Hz.

Reviewed By: neildhar

Differential Revision: D69156565

fbshipit-source-id: 52bae04c4da95d44c0e4e04c156e676fb96cd3e6

Author: avp

include/hermes/ConsoleHost/ConsoleHost.h

@@ -169,6 +169,9 @@ struct ExecuteOptions {
   /// If not None, run sampling profiler and dump the result.
   SampleProfilingMode sampleProfiling{SampleProfilingMode::None};
 
+  /// Sampling profiler frequency.
+  double sampleProfilingFreq{100};
+
   /// Start tracking heap objects before executing bytecode.
   bool heapTimeline{false};
 };

include/hermes/VM/RuntimeFlags.h

@@ -102,6 +102,12 @@ struct VMOnlyRuntimeFlags {
               "Dump profile in Tracery format")),
       llvh::cl::cat(RuntimeCategory)};
 
+  llvh::cl::opt<double> SampleProfilingFreq{
+      "sample-profiling-freq",
+      llvh::cl::init(100),
+      llvh::cl::desc("Sampling profiler frequency (in Hz)"),
+      llvh::cl::cat(RuntimeCategory)};
+
   llvh::cl::opt<MemorySize, false, MemorySizeParser> MaxHeapSize{
       "gc-max-heap",
       llvh::cl::desc("Max heap size.  Format: <unsigned>{K,M,G}{iB}"),

lib/ConsoleHost/ConsoleHost.cpp

@@ -452,7 +452,7 @@ bool executeHBCBytecodeImpl(
 
 #if HERMESVM_SAMPLING_PROFILER_AVAILABLE
   if (options.sampleProfiling != ExecuteOptions::SampleProfilingMode::None) {
-    vm::SamplingProfiler::enable();
+    vm::SamplingProfiler::enable(options.sampleProfilingFreq);
   }
 #endif // HERMESVM_SAMPLING_PROFILER_AVAILABLE
 

tools/hermes/hermes.cpp

@@ -124,6 +124,7 @@ static int executeHBCBytecodeFromCL(
   options.stopAfterInit = flags.StopAfterInit;
   options.forceGCBeforeStats = flags.GCBeforeStats;
   options.sampleProfiling = flags.SampleProfiling;
+  options.sampleProfilingFreq = flags.SampleProfilingFreq;
   options.heapTimeline = flags.HeapTimeline;
 
   bool success;