Add a new option -XX:+DisableEagerlyReleaseExplicitGC.

And use it by default in the 'art' script for benchmarking. This ensures
we can better track performance bottlenecks exposed by benchmarks.

Test: test.py
Change-Id: Ib37e5e1d2d4e5d13ab50392e3217f43ee8fe35e1

6 files changed, 18 insertions, 4 deletions

diff --git a/runtime/gc/collector/garbage_collector.cc b/runtime/gc/collector/garbage_collector.cc
index f35be96625..6eacf2c900 100644
--- a/runtime/gc/collector/garbage_collector.cc
+++ b/runtime/gc/collector/garbage_collector.cc
@@ -321,7 +321,8 @@ bool GarbageCollector::ShouldEagerlyReleaseMemoryToOS() const {
   if (runtime->IsZygote()) {
     return true;
   }
-  if (GetCurrentIteration()->GetGcCause() == kGcCauseExplicit) {
+  if (GetCurrentIteration()->GetGcCause() == kGcCauseExplicit &&
+      !runtime->IsEagerlyReleaseExplicitGcDisabled()) {
     // Our behavior with explicit GCs is to always release any available memory.
     return true;
   }
diff --git a/runtime/parsed_options.cc b/runtime/parsed_options.cc
index 7df765fe29..140503fd36 100644
--- a/runtime/parsed_options.cc
+++ b/runtime/parsed_options.cc
@@ -341,6 +341,8 @@ std::unique_ptr<RuntimeParser> ParsedOptions::MakeParser(bool ignore_unrecognize
           .IntoKey(M::BackgroundGc)
       .Define("-XX:+DisableExplicitGC")
           .IntoKey(M::DisableExplicitGC)
+      .Define("-XX:+DisableEagerlyReleaseExplicitGC")
+          .IntoKey(M::DisableEagerlyReleaseExplicitGC)
       .Define("-Xlockprofthreshold:_")
           .WithType<unsigned int>()
           .IntoKey(M::LockProfThreshold)
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index 62f6a1327d..5c86a81f93 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -250,6 +250,7 @@ Runtime::Runtime()
       must_relocate_(false),
       is_concurrent_gc_enabled_(true),
       is_explicit_gc_disabled_(false),
+      is_eagerly_release_explicit_gc_disabled_(false),
       image_dex2oat_enabled_(true),
       default_stack_size_(0),
       heap_(nullptr),
@@ -1504,6 +1505,8 @@ bool Runtime::Init(RuntimeArgumentMap&& runtime_options_in) {
   is_zygote_ = runtime_options.Exists(Opt::Zygote);
   is_primary_zygote_ = runtime_options.Exists(Opt::PrimaryZygote);
   is_explicit_gc_disabled_ = runtime_options.Exists(Opt::DisableExplicitGC);
+  is_eagerly_release_explicit_gc_disabled_ =
+      runtime_options.Exists(Opt::DisableEagerlyReleaseExplicitGC);
   image_dex2oat_enabled_ = runtime_options.GetOrDefault(Opt::ImageDex2Oat);
   dump_native_stack_on_sig_quit_ = runtime_options.GetOrDefault(Opt::DumpNativeStackOnSigQuit);
   allow_in_memory_compilation_ = runtime_options.Exists(Opt::AllowInMemoryCompilation);
diff --git a/runtime/runtime.h b/runtime/runtime.h
index fc8c050cf1..335ba546ab 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -217,6 +217,10 @@ class Runtime {
     return is_explicit_gc_disabled_;
   }
 
+  bool IsEagerlyReleaseExplicitGcDisabled() const {
+    return is_eagerly_release_explicit_gc_disabled_;
+  }
+
   std::string GetCompilerExecutable() const;
 
   const std::vector<std::string>& GetCompilerOptions() const {
@@ -1260,6 +1264,7 @@ class Runtime {
   bool must_relocate_;
   bool is_concurrent_gc_enabled_;
   bool is_explicit_gc_disabled_;
+  bool is_eagerly_release_explicit_gc_disabled_;
   bool image_dex2oat_enabled_;
 
   std::string compiler_executable_;
diff --git a/runtime/runtime_options.def b/runtime/runtime_options.def
index b2fcf7df13..d4e074273f 100644
--- a/runtime/runtime_options.def
+++ b/runtime/runtime_options.def
@@ -117,6 +117,7 @@ RUNTIME_OPTIONS_KEY (Memory<1>,           LargeObjectThreshold,           gc::He
 RUNTIME_OPTIONS_KEY (BackgroundGcOption,  BackgroundGc)
 
 RUNTIME_OPTIONS_KEY (Unit,                DisableExplicitGC)
+RUNTIME_OPTIONS_KEY (Unit,                DisableEagerlyReleaseExplicitGC)
 RUNTIME_OPTIONS_KEY (Unit,                NoSigChain)
 RUNTIME_OPTIONS_KEY (Unit,                ForceNativeBridge)
 RUNTIME_OPTIONS_KEY (LogVerbosity,        Verbose)
diff --git a/tools/art b/tools/art
index 662c4a0223..47724de9f9 100755
--- a/tools/art
+++ b/tools/art
@@ -330,9 +330,11 @@ ALLOW_DEFAULT_JDWP="no"
 VERBOSE="no"
 CLEAN_OAT_FILES="yes"
 RUN_DEX2OAT="yes"
-# 'art' script is for benchmarking, so override default JIT thresholds that are
-# too conservative for benchmarking.
-EXTRA_OPTIONS=(-Xjitwarmupthreshold:4000 -Xjitthreshold:10000)
+# 'art' script is for benchmarking, so override:
+# - default JIT thresholds that are too conservative for benchmarking
+# - the eagerly releasing memory to the OS on explicit GC, which is more suited
+#   for multi-apps execution than benchmarks.
+EXTRA_OPTIONS=(-Xjitwarmupthreshold:4000 -Xjitthreshold:10000 -XX:+DisableEagerlyReleaseExplicitGC)
 DEX2OAT_FLAGS=()
 DEX2OAT_CLASSPATH=()
 GENERATE_APP_IMAGE="no"