commit 273d11009876bca38065ace9a7743c7eceacbcce
author Mathieu Chartier <mathieuc@google.com> Tue Jun 06 17:07:13 2017 -0700
committer Mathieu Chartier <mathieuc@google.com> Fri Jun 09 14:28:51 2017 -0700
tree a2fedab1f90d9d605797d4050e40c6cda5e6d379
parent 29365184fe2e4f3d32f56b32edec8d03852b9556

Update startup compilation thresholds

This change aims to compile less startup methods to save RAM and
reduce code size. Numbers are from shortly after launching the apps.

Leave cutoff as 1 for high end devices for now. We may want to
revisit that later.

For low ram devices, the cutoff is 256. This regresses startup time
by 1% but saves more RAM. Results:
(odex+vdex) PSS: -25% average
odex size: -42% average
vdex size unchanged
Apps: Gmail, Maps, YouTube, Search

Spreadsheet at go/compilethreshold

Bug: 36457259
Test: test-art-host
Change-Id: I49d157df9379532d8d7a1ea1d844bb4beb195bb2

runtime/jit/profile_saver.cc

diff --git a/runtime/jit/profile_saver.cc b/runtime/jit/profile_saver.cc
index 68f33bd..edce9cd 100644
--- a/runtime/jit/profile_saver.cc
+++ b/runtime/jit/profile_saver.cc
@@ -251,7 +251,8 @@
   MethodReferenceCollection hot_methods(allocator.Adapter(), allocator.Adapter());
   MethodReferenceCollection startup_methods(allocator.Adapter(), allocator.Adapter());
   TypeReferenceCollection resolved_classes(allocator.Adapter(), allocator.Adapter());
-  const size_t hot_threshold = options_.GetHotStartupMethodSamples();
+  const bool is_low_ram = Runtime::Current()->GetHeap()->IsLowMemoryMode();
+  const size_t hot_threshold = options_.GetHotStartupMethodSamples(is_low_ram);
   {
     ScopedObjectAccess soa(self);
     gc::ScopedGCCriticalSection sgcs(self,

runtime/jit/profile_saver_options.h

diff --git a/runtime/jit/profile_saver_options.h b/runtime/jit/profile_saver_options.h
index 455bc1a..44550f4 100644
--- a/runtime/jit/profile_saver_options.h
+++ b/runtime/jit/profile_saver_options.h
@@ -24,16 +24,18 @@
   static constexpr uint32_t kSaveResolvedClassesDelayMs = 5 * 1000;  // 5 seconds
   // Minimum number of JIT samples during launch to mark a method as hot in the profile.
   static constexpr uint32_t kHotStartupMethodSamples = 1;
+  static constexpr uint32_t kHotStartupMethodSamplesLowRam = 256;
   static constexpr uint32_t kMinMethodsToSave = 10;
   static constexpr uint32_t kMinClassesToSave = 10;
   static constexpr uint32_t kMinNotificationBeforeWake = 10;
   static constexpr uint32_t kMaxNotificationBeforeWake = 50;
+  static constexpr uint32_t kHotStartupMethodSamplesNotSet = std::numeric_limits<uint32_t>::max();
 
   ProfileSaverOptions() :
     enabled_(false),
     min_save_period_ms_(kMinSavePeriodMs),
     save_resolved_classes_delay_ms_(kSaveResolvedClassesDelayMs),
-    hot_startup_method_samples_(kHotStartupMethodSamples),
+    hot_startup_method_samples_(kHotStartupMethodSamplesNotSet),
     min_methods_to_save_(kMinMethodsToSave),
     min_classes_to_save_(kMinClassesToSave),
     min_notification_before_wake_(kMinNotificationBeforeWake),
@@ -73,8 +75,12 @@
   uint32_t GetSaveResolvedClassesDelayMs() const {
     return save_resolved_classes_delay_ms_;
   }
-  uint32_t GetHotStartupMethodSamples() const {
-    return hot_startup_method_samples_;
+  uint32_t GetHotStartupMethodSamples(bool is_low_ram) const {
+    uint32_t ret = hot_startup_method_samples_;
+    if (ret == kHotStartupMethodSamplesNotSet) {
+      ret = is_low_ram ? kHotStartupMethodSamplesLowRam : kHotStartupMethodSamples;
+    }
+    return ret;
   }
   uint32_t GetMinMethodsToSave() const {
     return min_methods_to_save_;
@@ -107,6 +113,8 @@
   bool enabled_;
   uint32_t min_save_period_ms_;
   uint32_t save_resolved_classes_delay_ms_;
+  // Do not access hot_startup_method_samples_ directly for reading since it may be set to the
+  // placeholder default.
   uint32_t hot_startup_method_samples_;
   uint32_t min_methods_to_save_;
   uint32_t min_classes_to_save_;