Add build flag to force memcg to the v2 cgroup hierarchy (f8901767) · Commits · e / os / android_system_core

libprocessgroup/Android.bp

+23 −4

Original line number	Diff line number	Diff line
		@@ -2,9 +2,28 @@ package {
		default_applicable_licenses: ["Android-Apache-2.0"],
		}

		cc_defaults {
		name: "libprocessgroup_defaults",
		soong_config_module_type {
		name: "libprocessgroup_flag_aware_cc_defaults",
		module_type: "cc_defaults",
		config_namespace: "ANDROID",
		bool_variables: [
		"memcg_v2_force_enabled",
		],
		properties: [
		"cflags",
		],
		}

		libprocessgroup_flag_aware_cc_defaults {
		name: "libprocessgroup_build_flags_cc",
		cpp_std: "gnu++20",
		soong_config_variables: {
		memcg_v2_force_enabled: {
		cflags: [
		"-DMEMCG_V2_FORCE_ENABLED=true",
		],
		},
		},
		}

		cc_library_headers {
		@@ -67,7 +86,7 @@ cc_library {
		export_header_lib_headers: [
		"libprocessgroup_headers",
		],
		defaults: ["libprocessgroup_defaults"],
		defaults: ["libprocessgroup_build_flags_cc"],
		apex_available: [
		"//apex_available:platform",
		"//apex_available:anyapex",
		@@ -78,7 +97,7 @@ cc_library {
		cc_test {
		name: "task_profiles_test",
		host_supported: true,
		defaults: ["libprocessgroup_defaults"],
		defaults: ["libprocessgroup_build_flags_cc"],
		srcs: [
		"task_profiles_test.cpp",
		],

libprocessgroup/build_flags.h

0 → 100644

+29 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2024 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.
		*/

		#pragma once

		#ifndef MEMCG_V2_FORCE_ENABLED
		#define MEMCG_V2_FORCE_ENABLED false
		#endif

		namespace android::libprocessgroup_flags {

		inline consteval bool force_memcg_v2() {
		return MEMCG_V2_FORCE_ENABLED;
		}

		} // namespace android::libprocessgroup_flags

libprocessgroup/setup/Android.bp

+1 −4

Original line number	Diff line number	Diff line
		@@ -41,8 +41,5 @@ cc_library_shared {
		export_header_lib_headers: [
		"libprocessgroup_headers",
		],
		cflags: [
		"-Wall",
		"-Werror",
		],
		defaults: ["libprocessgroup_build_flags_cc"],
		}

libprocessgroup/setup/cgroup_map_write.cpp

+73 −3

Original line number	Diff line number	Diff line
		@@ -29,7 +29,7 @@
		#include <time.h>
		#include <unistd.h>

		#include <regex>
		#include <optional>

		#include <android-base/file.h>
		#include <android-base/logging.h>
		@@ -43,6 +43,7 @@
		#include <processgroup/processgroup.h>
		#include <processgroup/setup.h>

		#include "../build_flags.h"
		#include "cgroup_descriptor.h"

		using android::base::GetUintProperty;
		@@ -57,6 +58,8 @@ static constexpr const char* CGROUPS_DESC_VENDOR_FILE = "/vendor/etc/cgroups.jso

		static constexpr const char* TEMPLATE_CGROUPS_DESC_API_FILE = "/etc/task_profiles/cgroups_%u.json";

		static const std::string CGROUP_V2_ROOT_DEFAULT = "/sys/fs/cgroup";

		static bool ChangeDirModeAndOwner(const std::string& path, mode_t mode, const std::string& uid,
		const std::string& gid, bool permissive_mode = false) {
		uid_t pw_uid = -1;
		@@ -182,6 +185,8 @@ static void MergeCgroupToDescriptors(std::map<std::string, CgroupDescriptor>* de
		}
		}

		static const bool force_memcg_v2 = android::libprocessgroup_flags::force_memcg_v2();

		static bool ReadDescriptorsFromFile(const std::string& file_name,
		std::map<std::string, CgroupDescriptor>* descriptors) {
		std::vector<CgroupDescriptor> result;
		@@ -205,22 +210,41 @@ static bool ReadDescriptorsFromFile(const std::string& file_name,
		const Json::Value& cgroups = root["Cgroups"];
		for (Json::Value::ArrayIndex i = 0; i < cgroups.size(); ++i) {
		std::string name = cgroups[i]["Controller"].asString();

		if (force_memcg_v2 && name == "memory") continue;

		MergeCgroupToDescriptors(descriptors, cgroups[i], name, "", 1);
		}
		}

		bool memcgv2_present = false;
		std::string root_path;
		if (root.isMember("Cgroups2")) {
		const Json::Value& cgroups2 = root["Cgroups2"];
		std::string root_path = cgroups2["Path"].asString();
		root_path = cgroups2["Path"].asString();
		MergeCgroupToDescriptors(descriptors, cgroups2, CGROUPV2_HIERARCHY_NAME, "", 2);

		const Json::Value& childGroups = cgroups2["Controllers"];
		for (Json::Value::ArrayIndex i = 0; i < childGroups.size(); ++i) {
		std::string name = childGroups[i]["Controller"].asString();

		if (force_memcg_v2 && name == "memory") memcgv2_present = true;

		MergeCgroupToDescriptors(descriptors, childGroups[i], name, root_path, 2);
		}
		}

		if (force_memcg_v2 && !memcgv2_present) {
		LOG(INFO) << "Forcing memcg to v2 hierarchy";
		Json::Value memcgv2;
		memcgv2["Controller"] = "memory";
		memcgv2["NeedsActivation"] = true;
		memcgv2["Path"] = ".";
		memcgv2["Optional"] = true; // In case of cgroup_disabled=memory, so we can still boot
		MergeCgroupToDescriptors(descriptors, memcgv2, "memory",
		root_path.empty() ? CGROUP_V2_ROOT_DEFAULT : root_path, 2);
		}

		return true;
		}

		@@ -308,7 +332,8 @@ static bool ActivateV2CgroupController(const CgroupDescriptor& descriptor) {

		if (!base::WriteStringToFile(str, path)) {
		if (IsOptionalController(controller)) {
		PLOG(INFO) << "Failed to activate optional controller " << controller->name();
		PLOG(INFO) << "Failed to activate optional controller " << controller->name()
		<< " at " << path;
		return true;
		}
		PLOG(ERROR) << "Failed to activate controller " << controller->name();
		@@ -424,6 +449,40 @@ void CgroupDescriptor::set_mounted(bool mounted) {
		} // namespace cgrouprc
		} // namespace android

		static std::optional<bool> MGLRUDisabled() {
		const std::string file_name = "/sys/kernel/mm/lru_gen/enabled";
		std::string content;
		if (!android::base::ReadFileToString(file_name, &content)) {
		PLOG(ERROR) << "Failed to read MGLRU state from " << file_name;
		return {};
		}

		return content == "0x0000";
		}

		static std::optional<bool> MEMCGDisabled(
		const std::map<std::string, android::cgrouprc::CgroupDescriptor>& descriptors) {
		std::string cgroup_v2_root = android::cgrouprc::CGROUP_V2_ROOT_DEFAULT;
		const auto it = descriptors.find(CGROUPV2_HIERARCHY_NAME);
		if (it == descriptors.end()) {
		LOG(WARNING) << "No Cgroups2 path found in cgroups.json. Vendor has modified Android, and "
		<< "kernel memory use will be higher than intended.";
		} else if (it->second.controller()->path() != cgroup_v2_root) {
		cgroup_v2_root = it->second.controller()->path();
		}

		const std::string file_name = cgroup_v2_root + "/cgroup.controllers";
		std::string content;
		if (!android::base::ReadFileToString(file_name, &content)) {
		PLOG(ERROR) << "Failed to read cgroup controllers from " << file_name;
		return {};
		}

		// If we've forced memcg to v2 and it's not available, then it could only have been disabled
		// on the kernel command line (GKI sets CONFIG_MEMCG).
		return content.find("memory") == std::string::npos;
		}

		bool CgroupSetup() {
		using namespace android::cgrouprc;

		@@ -457,6 +516,17 @@ bool CgroupSetup() {
		}
		}

		if (force_memcg_v2) {
		if (MGLRUDisabled().value_or(false)) {
		LOG(WARNING) << "Memcg forced to v2 hierarchy with MGLRU disabled! "
		<< "Global reclaim performance will suffer.";
		}
		if (MEMCGDisabled(descriptors).value_or(false)) {
		LOG(WARNING) << "Memcg forced to v2 hierarchy while memcg is disabled by kernel "
		<< "command line!";
		}
		}

		// mkdir <CGROUPS_RC_DIR> 0711 system system
		if (!Mkdir(android::base::Dirname(CGROUPS_RC_PATH), 0711, "system", "system")) {
		LOG(ERROR) << "Failed to create directory for " << CGROUPS_RC_PATH << " file";