simpleperf/cmd_list.cpp - platform/system/extras - Git at Google

 /*
  * Copyright (C) 2015 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.
  */

 #include <sched.h>
 #include <stdio.h>

 #include <atomic>
 #include <map>
 #include <string>
 #include <thread>
 #include <vector>

 #include <android-base/file.h>
 #include <android-base/logging.h>

 #include "ETMRecorder.h"
 #include "command.h"
 #include "environment.h"
 #include "event_attr.h"
 #include "event_fd.h"
 #include "event_selection_set.h"
 #include "event_type.h"

 namespace simpleperf {

 extern std::unordered_map<std::string, std::unordered_set<int>> cpu_supported_raw_events;

 #if defined(__aarch64__) || defined(__arm__)
 extern std::unordered_map<uint64_t, std::string> arm64_cpuid_to_name;
 #endif  // defined(__aarch64__) || defined(__arm__)

 namespace {

 struct RawEventTestThreadArg {
   int cpu;
   std::atomic<pid_t> tid;
   std::atomic<bool> start;
 };

 static void RawEventTestThread(RawEventTestThreadArg* arg) {
   cpu_set_t mask;
   CPU_ZERO(&mask);
   CPU_SET(arg->cpu, &mask);
   int tid = gettid();
   sched_setaffinity(tid, sizeof(mask), &mask);
   arg->tid = tid;
   while (!arg->start) {
     std::this_thread::sleep_for(std::chrono::milliseconds(1));
   }
   TemporaryFile tmpfile;
   FILE* fp = fopen(tmpfile.path, "w");
   if (fp == nullptr) {
     return;
   }
   for (int i = 0; i < 10; ++i) {
     fprintf(fp, "output some data\n");
   }
   fclose(fp);
 }

 struct RawEventSupportStatus {
   std::vector<int> supported_cpus;
   std::vector<int> may_supported_cpus;
 };

 class RawEventSupportChecker {
  public:
   bool Init() {
 #if defined(__aarch64__) || defined(__arm__)
     cpu_models_ = GetARMCpuModels();
     if (cpu_models_.empty()) {
       LOG(ERROR) << "can't get device cpu info";
       return false;
     }
     for (const auto& model : cpu_models_) {
       uint64_t cpu_id = (static_cast<uint64_t>(model.implementer) << 32) | model.partnum;
       if (auto it = arm64_cpuid_to_name.find(cpu_id); it != arm64_cpuid_to_name.end()) {
         cpu_model_names_.push_back(it->second);
       } else {
         cpu_model_names_.push_back("");
       }
     }
 #endif  // defined(__aarch64__) || defined(__arm__)
     return true;
   }

   RawEventSupportStatus GetCpusSupportingEvent(const EventType& event_type) {
     RawEventSupportStatus status;
     std::string required_cpu_model;
     // For cpu model specific events, the limited_arch is like "arm64:Cortex-A520".
     if (auto pos = event_type.limited_arch.find(':'); pos != std::string::npos) {
       required_cpu_model = event_type.limited_arch.substr(pos + 1);
     }

     for (size_t i = 0; i < cpu_models_.size(); ++i) {
       const ARMCpuModel& model = cpu_models_[i];
       const std::string& model_name = cpu_model_names_[i];
       bool supported = false;
       bool may_supported = false;
       if (!required_cpu_model.empty()) {
         // This is a cpu model specific event, only supported on required_cpu_model.
         supported = model_name == required_cpu_model;
       } else if (!model_name.empty()) {
         // We know events supported on this cpu model.
         auto it = cpu_supported_raw_events.find(model_name);
         CHECK(it != cpu_supported_raw_events.end()) << "no events configuration for " << model_name;
         supported = it->second.count(event_type.config) > 0;
       } else {
         // We need to test the event support status.
         TestEventSupportOnCpu(event_type, model.cpus[0], supported, may_supported);
       }

       if (supported) {
         status.supported_cpus.insert(status.supported_cpus.end(), model.cpus.begin(),
                                      model.cpus.end());
       } else if (may_supported) {
         status.may_supported_cpus.insert(status.may_supported_cpus.end(), model.cpus.begin(),
                                          model.cpus.end());
       }
     }
     return status;
   }

  private:
   void TestEventSupportOnCpu(const EventType& event_type, int cpu, bool& supported,
                              bool& may_supported) {
     // Because the kernel may not check whether the raw event is supported by the cpu pmu.
     // We can't decide whether the raw event is supported by calling perf_event_open().
     // Instead, we can check if it can collect some real number.
     RawEventTestThreadArg test_thread_arg;
     test_thread_arg.cpu = cpu;
     test_thread_arg.tid = 0;
     test_thread_arg.start = false;
     std::thread test_thread(RawEventTestThread, &test_thread_arg);
     while (test_thread_arg.tid == 0) {
       std::this_thread::sleep_for(std::chrono::milliseconds(1));
     }
     perf_event_attr attr = CreateDefaultPerfEventAttr(event_type);
     std::unique_ptr<EventFd> event_fd = EventFd::OpenEventFile(
         attr, test_thread_arg.tid, test_thread_arg.cpu, nullptr, event_type.name, false);
     test_thread_arg.start = true;
     test_thread.join();
     if (event_fd == nullptr) {
       supported = may_supported = false;
       return;
     }
     PerfCounter counter;
     if (!event_fd->ReadCounter(&counter)) {
       supported = may_supported = false;
       return;
     }
     if (counter.value != 0) {
       supported = true;
       may_supported = false;
     } else {
       supported = false;
       may_supported = true;
     }
   }

   std::vector<ARMCpuModel> cpu_models_;
   std::vector<std::string> cpu_model_names_;
 };

 static std::string ToCpuString(const std::vector<int>& cpus) {
   std::string s;
   if (cpus.empty()) {
     return s;
   }
   s += std::to_string(cpus[0]);
   int last_cpu = cpus[0];
   bool added = true;
   for (size_t i = 1; i < cpus.size(); ++i) {
     if (cpus[i] == last_cpu + 1) {
       last_cpu = cpus[i];
       added = false;
     } else {
       s += "-" + std::to_string(last_cpu) + "," + std::to_string(cpus[i]);
       last_cpu = cpus[i];
       added = true;
     }
   }
   if (!added) {
     s += "-" + std::to_string(last_cpu);
   }
   return s;
 }

 static void PrintRawEventTypes(const std::string& type_desc) {
   printf("List of %s:\n", type_desc.c_str());
 #if defined(__aarch64__) || defined(__arm__)
   printf(
       // clang-format off
 "  # Please refer to \"PMU common architectural and microarchitectural event numbers\"\n"
 "  # and \"ARM recommendations for IMPLEMENTATION DEFINED event numbers\" listed in\n"
 "  # ARMv9 manual for details.\n"
 "  # A possible link is https://developer.arm.com/documentation/ddi0487.\n"
       // clang-format on
   );
 #endif  // defined(__aarch64__) || defined(__arm__)
   RawEventSupportChecker support_checker;
   if (!support_checker.Init()) {
     return;
   }
   auto callback = [&](const EventType& event_type) {
     if (event_type.type != PERF_TYPE_RAW) {
       return true;
     }
     RawEventSupportStatus status = support_checker.GetCpusSupportingEvent(event_type);
     if (status.supported_cpus.empty() && status.may_supported_cpus.empty()) {
       return true;
     }
     std::string text = "  " + event_type.name + " (";
     if (!status.supported_cpus.empty()) {
       text += "supported on cpu " + ToCpuString(status.supported_cpus);
       if (!status.may_supported_cpus.empty()) {
         text += ", ";
       }
     }
     if (!status.may_supported_cpus.empty()) {
       text += "may supported on cpu " + ToCpuString(status.may_supported_cpus);
     }
     text += ")";
     printf("%s", text.c_str());
     if (!event_type.description.empty()) {
       printf("\t\t# %s", event_type.description.c_str());
     }
     printf("\n");
     return true;
   };
   EventTypeManager::Instance().ForEachType(callback);
   printf("\n");
 }

 static bool IsEventTypeSupported(const EventType& event_type) {
   // PMU and tracepoint events are provided by kernel. So we assume they're supported.
   if (event_type.IsPmuEvent() || event_type.IsTracepointEvent()) {
     return true;
   }
   perf_event_attr attr = CreateDefaultPerfEventAttr(event_type);
   // Exclude kernel to list supported events even when kernel recording isn't allowed.
   attr.exclude_kernel = 1;
   return IsEventAttrSupported(attr, event_type.name);
 }

 static void PrintEventTypesOfType(const std::string& type_name, const std::string& type_desc,
                                   const std::function<bool(const EventType&)>& is_type_fn) {
   if (type_name == "raw") {
     return PrintRawEventTypes(type_desc);
   }
   printf("List of %s:\n", type_desc.c_str());
   if (GetTargetArch() == ARCH_ARM || GetTargetArch() == ARCH_ARM64) {
     if (type_name == "cache") {
       printf("  # More cache events are available in `simpleperf list raw`.\n");
     }
   }
   auto callback = [&](const EventType& event_type) {
     if (is_type_fn(event_type)) {
       if (!IsEventTypeSupported(event_type)) {
         return true;
       }
       printf("  %s", event_type.name.c_str());
       if (!event_type.description.empty()) {
         printf("\t\t# %s", event_type.description.c_str());
       }
       printf("\n");
     }
     return true;
   };
   EventTypeManager::Instance().ForEachType(callback);
   printf("\n");
 }

 class ListCommand : public Command {
  public:
   ListCommand()
       : Command("list", "list available event types",
                 // clang-format off
 "Usage: simpleperf list [options] [hw|sw|cache|raw|tracepoint|pmu]\n"
 "       List all available event types.\n"
 "       Filters can be used to show only event types belong to selected types:\n"
 "         hw          hardware events\n"
 "         sw          software events\n"
 "         cache       hardware cache events\n"
 "         raw         raw cpu pmu events\n"
 "         tracepoint  tracepoint events\n"
 "         cs-etm      coresight etm instruction tracing events\n"
 "         pmu         system-specific pmu events\n"
 "Options:\n"
 "--show-features    Show features supported on the device, including:\n"
 "                     dwarf-based-call-graph\n"
 "                     trace-offcpu\n"
                 // clang-format on
         ) {}

   bool Run(const std::vector<std::string>& args) override;

  private:
   void ShowFeatures();
 };

 bool ListCommand::Run(const std::vector<std::string>& args) {
   if (!CheckPerfEventLimit()) {
     return false;
   }

   static std::map<std::string, std::pair<std::string, std::function<bool(const EventType&)>>>
       type_map =
   { {"hw", {"hardware events", [](const EventType& e) { return e.type == PERF_TYPE_HARDWARE; }}},
     {"sw", {"software events", [](const EventType& e) { return e.type == PERF_TYPE_SOFTWARE; }}},
     {"cache", {"hw-cache events", [](const EventType& e) { return e.type == PERF_TYPE_HW_CACHE; }}},
     {"raw",
      {"raw events provided by cpu pmu",
       [](const EventType& e) { return e.type == PERF_TYPE_RAW; }}},
     {"tracepoint",
      {"tracepoint events", [](const EventType& e) { return e.type == PERF_TYPE_TRACEPOINT; }}},
 #if defined(__arm__) || defined(__aarch64__)
     {"cs-etm",
      {"coresight etm events",
       [](const EventType& e) { return e.type == ETMRecorder::GetInstance().GetEtmEventType(); }}},
 #endif
     {"pmu", {"pmu events", [](const EventType& e) { return e.IsPmuEvent(); }}},
   };

   std::vector<std::string> names;
   if (args.empty()) {
     for (auto& item : type_map) {
       names.push_back(item.first);
     }
   } else {
     for (auto& arg : args) {
       if (type_map.find(arg) != type_map.end()) {
         names.push_back(arg);
       } else if (arg == "--show-features") {
         ShowFeatures();
         return true;
       } else {
         LOG(ERROR) << "unknown event type category: " << arg << ", try using \"help list\"";
         return false;
       }
     }
   }

   for (auto& name : names) {
     auto it = type_map.find(name);
     PrintEventTypesOfType(name, it->second.first, it->second.second);
   }
   return true;
 }

 void ListCommand::ShowFeatures() {
   if (IsDwarfCallChainSamplingSupported()) {
     printf("dwarf-based-call-graph\n");
   }
   if (IsDumpingRegsForTracepointEventsSupported()) {
     printf("trace-offcpu\n");
   }
   if (IsSettingClockIdSupported()) {
     printf("set-clockid\n");
   }
 }

 }  // namespace

 void RegisterListCommand() {
   RegisterCommand("list", [] { return std::unique_ptr<Command>(new ListCommand); });
 }

 }  // namespace simpleperf
	/*
	* Copyright (C) 2015 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.
	*/

	#include <sched.h>
	#include <stdio.h>

	#include <atomic>
	#include <map>
	#include <string>
	#include <thread>
	#include <vector>

	#include <android-base/file.h>
	#include <android-base/logging.h>

	#include "ETMRecorder.h"
	#include "command.h"
	#include "environment.h"
	#include "event_attr.h"
	#include "event_fd.h"
	#include "event_selection_set.h"
	#include "event_type.h"

	namespace simpleperf {

	extern std::unordered_map<std::string, std::unordered_set<int>> cpu_supported_raw_events;

	#if defined(__aarch64__) \|\| defined(__arm__)
	extern std::unordered_map<uint64_t, std::string> arm64_cpuid_to_name;
	#endif // defined(__aarch64__) \|\| defined(__arm__)

	namespace {

	struct RawEventTestThreadArg {
	int cpu;
	std::atomic<pid_t> tid;
	std::atomic<bool> start;
	};

	static void RawEventTestThread(RawEventTestThreadArg* arg) {
	cpu_set_t mask;
	CPU_ZERO(&mask);
	CPU_SET(arg->cpu, &mask);
	int tid = gettid();
	sched_setaffinity(tid, sizeof(mask), &mask);
	arg->tid = tid;
	while (!arg->start) {
	std::this_thread::sleep_for(std::chrono::milliseconds(1));
	}
	TemporaryFile tmpfile;
	FILE* fp = fopen(tmpfile.path, "w");
	if (fp == nullptr) {
	return;
	}
	for (int i = 0; i < 10; ++i) {
	fprintf(fp, "output some data\n");
	}
	fclose(fp);
	}

	struct RawEventSupportStatus {
	std::vector<int> supported_cpus;
	std::vector<int> may_supported_cpus;
	};

	class RawEventSupportChecker {
	public:
	bool Init() {
	#if defined(__aarch64__) \|\| defined(__arm__)
	cpu_models_ = GetARMCpuModels();
	if (cpu_models_.empty()) {
	LOG(ERROR) << "can't get device cpu info";
	return false;
	}
	for (const auto& model : cpu_models_) {
	uint64_t cpu_id = (static_cast<uint64_t>(model.implementer) << 32) \| model.partnum;
	if (auto it = arm64_cpuid_to_name.find(cpu_id); it != arm64_cpuid_to_name.end()) {
	cpu_model_names_.push_back(it->second);
	} else {
	cpu_model_names_.push_back("");
	}
	}
	#endif // defined(__aarch64__) \|\| defined(__arm__)
	return true;
	}

	RawEventSupportStatus GetCpusSupportingEvent(const EventType& event_type) {
	RawEventSupportStatus status;
	std::string required_cpu_model;
	// For cpu model specific events, the limited_arch is like "arm64:Cortex-A520".
	if (auto pos = event_type.limited_arch.find(':'); pos != std::string::npos) {
	required_cpu_model = event_type.limited_arch.substr(pos + 1);
	}

	for (size_t i = 0; i < cpu_models_.size(); ++i) {
	const ARMCpuModel& model = cpu_models_[i];
	const std::string& model_name = cpu_model_names_[i];
	bool supported = false;
	bool may_supported = false;
	if (!required_cpu_model.empty()) {
	// This is a cpu model specific event, only supported on required_cpu_model.
	supported = model_name == required_cpu_model;
	} else if (!model_name.empty()) {
	// We know events supported on this cpu model.
	auto it = cpu_supported_raw_events.find(model_name);
	CHECK(it != cpu_supported_raw_events.end()) << "no events configuration for " << model_name;
	supported = it->second.count(event_type.config) > 0;
	} else {
	// We need to test the event support status.
	TestEventSupportOnCpu(event_type, model.cpus[0], supported, may_supported);
	}

	if (supported) {
	status.supported_cpus.insert(status.supported_cpus.end(), model.cpus.begin(),
	model.cpus.end());
	} else if (may_supported) {
	status.may_supported_cpus.insert(status.may_supported_cpus.end(), model.cpus.begin(),
	model.cpus.end());
	}
	}
	return status;
	}

	private:
	void TestEventSupportOnCpu(const EventType& event_type, int cpu, bool& supported,
	bool& may_supported) {
	// Because the kernel may not check whether the raw event is supported by the cpu pmu.
	// We can't decide whether the raw event is supported by calling perf_event_open().
	// Instead, we can check if it can collect some real number.
	RawEventTestThreadArg test_thread_arg;
	test_thread_arg.cpu = cpu;
	test_thread_arg.tid = 0;
	test_thread_arg.start = false;
	std::thread test_thread(RawEventTestThread, &test_thread_arg);
	while (test_thread_arg.tid == 0) {
	std::this_thread::sleep_for(std::chrono::milliseconds(1));
	}
	perf_event_attr attr = CreateDefaultPerfEventAttr(event_type);
	std::unique_ptr<EventFd> event_fd = EventFd::OpenEventFile(
	attr, test_thread_arg.tid, test_thread_arg.cpu, nullptr, event_type.name, false);
	test_thread_arg.start = true;
	test_thread.join();
	if (event_fd == nullptr) {
	supported = may_supported = false;
	return;
	}
	PerfCounter counter;
	if (!event_fd->ReadCounter(&counter)) {
	supported = may_supported = false;
	return;
	}
	if (counter.value != 0) {
	supported = true;
	may_supported = false;
	} else {
	supported = false;
	may_supported = true;
	}
	}

	std::vector<ARMCpuModel> cpu_models_;
	std::vector<std::string> cpu_model_names_;
	};

	static std::string ToCpuString(const std::vector<int>& cpus) {
	std::string s;
	if (cpus.empty()) {
	return s;
	}
	s += std::to_string(cpus[0]);
	int last_cpu = cpus[0];
	bool added = true;
	for (size_t i = 1; i < cpus.size(); ++i) {
	if (cpus[i] == last_cpu + 1) {
	last_cpu = cpus[i];
	added = false;
	} else {
	s += "-" + std::to_string(last_cpu) + "," + std::to_string(cpus[i]);
	last_cpu = cpus[i];
	added = true;
	}
	}
	if (!added) {
	s += "-" + std::to_string(last_cpu);
	}
	return s;
	}

	static void PrintRawEventTypes(const std::string& type_desc) {
	printf("List of %s:\n", type_desc.c_str());
	#if defined(__aarch64__) \|\| defined(__arm__)
	printf(
	// clang-format off
	" # Please refer to \"PMU common architectural and microarchitectural event numbers\"\n"
	" # and \"ARM recommendations for IMPLEMENTATION DEFINED event numbers\" listed in\n"
	" # ARMv9 manual for details.\n"
	" # A possible link is https://developer.arm.com/documentation/ddi0487.\n"
	// clang-format on
	);
	#endif // defined(__aarch64__) \|\| defined(__arm__)
	RawEventSupportChecker support_checker;
	if (!support_checker.Init()) {
	return;
	}
	auto callback = [&](const EventType& event_type) {
	if (event_type.type != PERF_TYPE_RAW) {
	return true;
	}
	RawEventSupportStatus status = support_checker.GetCpusSupportingEvent(event_type);
	if (status.supported_cpus.empty() && status.may_supported_cpus.empty()) {
	return true;
	}
	std::string text = " " + event_type.name + " (";
	if (!status.supported_cpus.empty()) {
	text += "supported on cpu " + ToCpuString(status.supported_cpus);
	if (!status.may_supported_cpus.empty()) {
	text += ", ";
	}
	}
	if (!status.may_supported_cpus.empty()) {
	text += "may supported on cpu " + ToCpuString(status.may_supported_cpus);
	}
	text += ")";
	printf("%s", text.c_str());
	if (!event_type.description.empty()) {
	printf("\t\t# %s", event_type.description.c_str());
	}
	printf("\n");
	return true;
	};
	EventTypeManager::Instance().ForEachType(callback);
	printf("\n");
	}

	static bool IsEventTypeSupported(const EventType& event_type) {
	// PMU and tracepoint events are provided by kernel. So we assume they're supported.
	if (event_type.IsPmuEvent() \|\| event_type.IsTracepointEvent()) {
	return true;
	}
	perf_event_attr attr = CreateDefaultPerfEventAttr(event_type);
	// Exclude kernel to list supported events even when kernel recording isn't allowed.
	attr.exclude_kernel = 1;
	return IsEventAttrSupported(attr, event_type.name);
	}

	static void PrintEventTypesOfType(const std::string& type_name, const std::string& type_desc,
	const std::function<bool(const EventType&)>& is_type_fn) {
	if (type_name == "raw") {
	return PrintRawEventTypes(type_desc);
	}
	printf("List of %s:\n", type_desc.c_str());
	if (GetTargetArch() == ARCH_ARM \|\| GetTargetArch() == ARCH_ARM64) {
	if (type_name == "cache") {
	printf(" # More cache events are available in `simpleperf list raw`.\n");
	}
	}
	auto callback = [&](const EventType& event_type) {
	if (is_type_fn(event_type)) {
	if (!IsEventTypeSupported(event_type)) {
	return true;
	}
	printf(" %s", event_type.name.c_str());
	if (!event_type.description.empty()) {
	printf("\t\t# %s", event_type.description.c_str());
	}
	printf("\n");
	}
	return true;
	};
	EventTypeManager::Instance().ForEachType(callback);
	printf("\n");
	}

	class ListCommand : public Command {
	public:
	ListCommand()
	: Command("list", "list available event types",
	// clang-format off
	"Usage: simpleperf list [options] [hw\|sw\|cache\|raw\|tracepoint\|pmu]\n"
	" List all available event types.\n"
	" Filters can be used to show only event types belong to selected types:\n"
	" hw hardware events\n"
	" sw software events\n"
	" cache hardware cache events\n"
	" raw raw cpu pmu events\n"
	" tracepoint tracepoint events\n"
	" cs-etm coresight etm instruction tracing events\n"
	" pmu system-specific pmu events\n"
	"Options:\n"
	"--show-features Show features supported on the device, including:\n"
	" dwarf-based-call-graph\n"
	" trace-offcpu\n"
	// clang-format on
	) {}

	bool Run(const std::vector<std::string>& args) override;

	private:
	void ShowFeatures();
	};

	bool ListCommand::Run(const std::vector<std::string>& args) {
	if (!CheckPerfEventLimit()) {
	return false;
	}

	static std::map<std::string, std::pair<std::string, std::function<bool(const EventType&)>>>
	type_map =
	{ {"hw", {"hardware events", [](const EventType& e) { return e.type == PERF_TYPE_HARDWARE; }}},
	{"sw", {"software events", [](const EventType& e) { return e.type == PERF_TYPE_SOFTWARE; }}},
	{"cache", {"hw-cache events", [](const EventType& e) { return e.type == PERF_TYPE_HW_CACHE; }}},
	{"raw",
	{"raw events provided by cpu pmu",
	[](const EventType& e) { return e.type == PERF_TYPE_RAW; }}},
	{"tracepoint",
	{"tracepoint events", [](const EventType& e) { return e.type == PERF_TYPE_TRACEPOINT; }}},
	#if defined(__arm__) \|\| defined(__aarch64__)
	{"cs-etm",
	{"coresight etm events",
	[](const EventType& e) { return e.type == ETMRecorder::GetInstance().GetEtmEventType(); }}},
	#endif
	{"pmu", {"pmu events", [](const EventType& e) { return e.IsPmuEvent(); }}},
	};

	std::vector<std::string> names;
	if (args.empty()) {
	for (auto& item : type_map) {
	names.push_back(item.first);
	}
	} else {
	for (auto& arg : args) {
	if (type_map.find(arg) != type_map.end()) {
	names.push_back(arg);
	} else if (arg == "--show-features") {
	ShowFeatures();
	return true;
	} else {
	LOG(ERROR) << "unknown event type category: " << arg << ", try using \"help list\"";
	return false;
	}
	}
	}

	for (auto& name : names) {
	auto it = type_map.find(name);
	PrintEventTypesOfType(name, it->second.first, it->second.second);
	}
	return true;
	}

	void ListCommand::ShowFeatures() {
	if (IsDwarfCallChainSamplingSupported()) {
	printf("dwarf-based-call-graph\n");
	}
	if (IsDumpingRegsForTracepointEventsSupported()) {
	printf("trace-offcpu\n");
	}
	if (IsSettingClockIdSupported()) {
	printf("set-clockid\n");
	}
	}

	} // namespace

	void RegisterListCommand() {
	RegisterCommand("list", [] { return std::unique_ptr<Command>(new ListCommand); });
	}

	} // namespace simpleperf