Add sampling profiler
This adds a sampling profiler thread that runs every so often, gathering
profiling data and writing the results to a file in /data/data (specific to
app running). The intention is to use these files as input to the compiler
so that it can determine the best methods to compile.
Bug: 11539952
Change-Id: I0bfbb4146fb7966673c792f017ffac8107b6272d
diff --git a/runtime/profiler.h b/runtime/profiler.h
new file mode 100644
index 0000000..e3af47c
--- /dev/null
+++ b/runtime/profiler.h
@@ -0,0 +1,174 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_PROFILER_H_
+#define ART_RUNTIME_PROFILER_H_
+
+#include <ostream>
+#include <set>
+#include <string>
+#include <vector>
+
+#include "base/macros.h"
+#include "globals.h"
+#include "instrumentation.h"
+#include "os.h"
+#include "safe_map.h"
+#include "base/mutex.h"
+#include "locks.h"
+#include "UniquePtr.h"
+#include "barrier.h"
+
+namespace art {
+
+namespace mirror {
+ class ArtMethod;
+ class Class;
+} // namespace mirror
+class Thread;
+
+
+//
+// This class holds all the results for all runs of the profiler. It also
+// counts the number of null methods (where we can't determine the method) and
+// the number of methods in the boot path (where we have already compiled the method).
+//
+// This object is an internal profiler object and uses the same locking as the profiler
+// itself.
+class ProfileSampleResults {
+ public:
+ explicit ProfileSampleResults(Mutex& lock);
+ ~ProfileSampleResults();
+
+ void Put(mirror::ArtMethod* method);
+ uint32_t Write(std::ostream &os);
+ void Clear();
+ uint32_t GetNumSamples() { return num_samples_; }
+ void NullMethod() { ++num_null_methods_; }
+ void BootMethod() { ++num_boot_methods_; }
+ private:
+ uint32_t Hash(mirror::ArtMethod* method);
+ static constexpr int kHashSize = 17;
+ Mutex& lock_; // Reference to the main profiler lock - we don't need two of them.
+ uint32_t num_samples_; // Total number of samples taken.
+ uint32_t num_null_methods_; // Number of samples where can don't know the method.
+ uint32_t num_boot_methods_; // Number of samples in the boot path.
+
+ typedef std::map<mirror::ArtMethod*, uint32_t> Map; // Map of method vs its count.
+ Map *table[kHashSize];
+};
+
+//
+// The BackgroundMethodSamplingProfiler runs in a thread. Most of the time it is sleeping but
+// occasionally wakes up and counts the number of times a method is called. Each time
+// it ticks, it looks at the current method and records it in the ProfileSampleResults
+// table.
+//
+// The timing is controlled by a number of variables:
+// 1. Period: the time between sampling runs.
+// 2. Interval: the time between each sample in a run.
+// 3. Duration: the duration of a run.
+//
+// So the profiler thread is sleeping for the 'period' time. It wakes up and runs for the
+// 'duration'. The run consists of a series of samples, each of which is 'interval' microseconds
+// apart. At the end of a run, it writes the results table to a file and goes back to sleep.
+
+class BackgroundMethodSamplingProfiler {
+ public:
+ static void Start(int period, int duration, std::string profile_filename, int interval_us,
+ double backoff_coefficient, bool startImmediately)
+ LOCKS_EXCLUDED(Locks::mutator_lock_,
+ Locks::thread_list_lock_,
+ Locks::thread_suspend_count_lock_,
+ Locks::profiler_lock_);
+
+ static void Stop() LOCKS_EXCLUDED(Locks::profiler_lock_, wait_lock_);
+ static void Shutdown() LOCKS_EXCLUDED(Locks::profiler_lock_);
+
+ void RecordMethod(mirror::ArtMethod *method) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
+ Barrier& GetBarrier() {
+ return *profiler_barrier_;
+ }
+
+ private:
+ explicit BackgroundMethodSamplingProfiler(int period, int duration, std::string profile_filename,
+ double backoff_coefficient, int interval_us, bool startImmediately);
+
+ // The sampling interval in microseconds is passed as an argument.
+ static void* RunProfilerThread(void* arg) LOCKS_EXCLUDED(Locks::profiler_lock_);
+
+ uint32_t WriteProfile() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
+ void CleanProfile();
+ uint32_t DumpProfile(std::ostream& os) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+ static bool ShuttingDown(Thread* self) LOCKS_EXCLUDED(Locks::profiler_lock_);
+
+ static BackgroundMethodSamplingProfiler* profiler_ GUARDED_BY(Locks::profiler_lock_);
+
+ // We need to shut the sample thread down at exit. Setting this to true will do that.
+ static volatile bool shutting_down_ GUARDED_BY(Locks::profiler_lock_);
+
+ // Sampling thread, non-zero when sampling.
+ static pthread_t profiler_pthread_;
+
+ // Some measure of the number of samples that are significant
+ static constexpr uint32_t kSignificantSamples = 10;
+
+ // File to write profile data out to. Cannot be empty if we are profiling.
+ std::string profile_file_name_;
+
+ // Number of seconds between profile runs.
+ uint32_t period_s_;
+
+ // Most of the time we want to delay the profiler startup to prevent everything
+ // running at the same time (all processes). This is the default, but if we
+ // want to override this, set the 'start_immediately_' to true. This is done
+ // if the -Xprofile option is given on the command line.
+ bool start_immediately_;
+
+ uint32_t interval_us_;
+
+ // A backoff coefficent to adjust the profile period based on time.
+ double backoff_factor_;
+
+ // How much to increase the backoff by on each profile iteration.
+ double backoff_coefficient_;
+
+ // Duration of each profile run. The profile file will be written at the end
+ // of each run.
+ uint32_t duration_s_;
+
+ // Profile condition support.
+ Mutex wait_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
+ ConditionVariable period_condition_ GUARDED_BY(wait_lock_);
+
+ ProfileSampleResults profile_table_;
+
+ UniquePtr<Barrier> profiler_barrier_;
+
+ // Set of methods to be filtered out. This will probably be rare because
+ // most of the methods we want to be filtered reside in the boot path and
+ // are automatically filtered.
+ typedef std::set<std::string> FilteredMethods;
+ FilteredMethods filtered_methods_;
+
+ DISALLOW_COPY_AND_ASSIGN(BackgroundMethodSamplingProfiler);
+};
+
+} // namespace art
+
+#endif // ART_RUNTIME_PROFILER_H_