1 原理说明
这个方案有如下基本需求:
- 构建自定义CPUSET,/dev/cpuset中包含一个全新的cpuset分组。且可以通过set_cpuset_policy和set_sched_policy接口可以设置自定义CPUSET。
- 开机启动后可以通过zygote判定来对特定的应用进程设置CPUSET,并一直保持,且保证自定义CPUSET不受其他CPUSET影响,持续独立。
原理上因为修改代码涉及部分较多,因此共分3个部分:
- framework修改:添加SCHED GROUP和THREAD GROUP(THREAD_GROUP_对应SP_)的支持,且支持开机启动后直接设置。applyOomAdjLSP的判定保持不变。
- system修改:添加SP_CUSTOM的支持及set_cpuset_policy和set_sched_policy接口等支持,同时修改task_profiles.json,添加SP_CUSTOM CPUSET的支持。
- init.rc修改及编译部分调整:对自定义cpuset节点进行操作,vndk部分编译需要重新调整方案以及不修改VNDK如何保证编译通过。
由于修改中涉及代码量过大,这里拆分成两节进行展示。本章节主要针对第2部分和第3部分修改进行说明。上一篇文章👇
Android Framework 常见解决方案(25-1)定制CPUSET解决方案-framework部分修改
主要对第1部分修改进行说明。
2 修改方案(Android S)
2.1 system部分修改
针对system分区修改。具体修改方案如下(这里以S版本修改为主,Q和R有一些差异但原理不变):
在$AOSP/system/core/libprocessgroup/include/processgroup/sched_policy.h文件中修改:
/* Keep in sync with THREAD_GROUP_* in frameworks/base/core/java/android/os/Process.java */
typedef enum {SP_DEFAULT = -1,SP_BACKGROUND = 0,SP_FOREGROUND = 1,SP_SYSTEM = 2,SP_AUDIO_APP = 3,SP_AUDIO_SYS = 4,SP_TOP_APP = 5,SP_RT_APP = 6,SP_RESTRICTED = 7,
+ SP_CUSTOM = 8,SP_CNT,SP_MAX = SP_CNT - 1,SP_SYSTEM_DEFAULT = SP_FOREGROUND,
} SchedPolicy;
这里注意,按照顺序填写修改相对简单,因为后续会用到SP_CNT和SP_MAX这两个变量,代码中还会有许多的遍历操作,因此最好采用累加方案,不要设置其他值。
本方案的修改比较全面,即支持set_cpuset_policy,也兼容到set_sched_policy,在实际操作中,可根据需要只修改其中一个即可。
在$AOSP/system/core/libprocessgroup/sched_policy.cpp文件中修改:
//修改set_cpuset_policy,添加SP_CUSTOM的处理
int set_cpuset_policy(int tid, SchedPolicy policy) {if (tid == 0) {tid = GetThreadId();}policy = _policy(policy);switch (policy) {case SP_BACKGROUND:return SetTaskProfiles(tid, {"CPUSET_SP_BACKGROUND", "BlkIOBackground"}, true) ? 0 : -1;case SP_FOREGROUND:return SetTaskProfiles(tid, {"CPUSET_SP_FOREGROUND", "BlkIOForeground"}, true) ? 0 : -1;case SP_AUDIO_APP:case SP_AUDIO_SYS:return SetTaskProfiles(tid, {"CPUSET_SP_FOREGROUND", "AudioAppCapacity", "BlkIOForeground"}, true) ? 0 : -1;case SP_TOP_APP:return SetTaskProfiles(tid, {"CPUSET_SP_TOP_APP", "BlkIOBackground"}, true) ? 0 : -1;case SP_SYSTEM:return SetTaskProfiles(tid, {"CPUSET_SP_SYSTEM", "BlkIOForeground"}, true) ? 0 : -1;case SP_RESTRICTED:return SetTaskProfiles(tid, {"CPUSET_SP_RESTRICTED"}, true) ? 0 : -1;
+ case SP_CUSTOM:
+ return SetTaskProfiles(tid, {"CPUSET_SP_CUSTOM"}, true) ? 0 : -1;default:break;}return 0;
}//修改set_sched_policy,添加SP_CUSTOM的处理
int set_sched_policy(int tid, SchedPolicy policy) {
//...
#if POLICY_DEBUG //注意:这一段的修改主要是调试使用,功能实现上可以不添加该部分
//...switch (policy) {case SP_BACKGROUND:SLOGD("vvv tid %d (%s)", tid, thread_name);break;case SP_FOREGROUND:case SP_AUDIO_APP:case SP_AUDIO_SYS:case SP_TOP_APP:SLOGD("^^^ tid %d policy %d (%s)", tid, policy, thread_name);break;case SP_SYSTEM:SLOGD("/// tid %d (%s)", tid, thread_name);break;case SP_RT_APP:SLOGD("RT tid %d (%s)", tid, thread_name);break;
+ case SP_CUSTOM:
+ SLOGD("CUSTOM|xxx tid %d (%s)", tid, thread_name);
+ break;default:SLOGD("??? tid %d (%s)", tid, thread_name);break;}
#endif
//...switch (policy) {case SP_BACKGROUND:return SetTaskProfiles(tid, {"SCHED_SP_BACKGROUND", "BlkIOBackground"}, true) ? 0 : -1;case SP_FOREGROUND:case SP_AUDIO_APP:case SP_AUDIO_SYS:return SetTaskProfiles(tid, {"SCHED_SP_FOREGROUND", "BlkIOForeground"}, true) ? 0 : -1;case SP_TOP_APP:return SetTaskProfiles(tid, {"SCHED_SP_TOP_APP", "BlkIOForeground"}, true) ? 0 : -1;case SP_SYSTEM:return SetTaskProfiles(tid, {"SCHED_SP_SYSTEM"}, true) ? 0 : -1;case SP_RT_APP:return SetTaskProfiles(tid, {"SCHED_SP_RT_APP", "BlkIOForeground"}, true) ? 0 : -1;case SP_CUSTOM:return SetTaskProfiles(tid, {"SCHED_SP_CUSTOM"}, true) ? 0 : -1;default:return SetTaskProfiles(tid, {"SCHED_SP_DEFAULT"}, true) ? 0 : -1;}return 0;}
//修改get_sched_policy_from_group,添加SP_CUSTOM的处理
static int get_sched_policy_from_group(const std::string& group, SchedPolicy* policy) {if (group.empty()) {*policy = SP_FOREGROUND;} else if (group == "foreground") {*policy = SP_FOREGROUND;} else if (group == "system-background") {*policy = SP_SYSTEM;} else if (group == "background") {*policy = SP_BACKGROUND;} else if (group == "top-app") {*policy = SP_TOP_APP;} else if (group == "restricted") {*policy = SP_RESTRICTED;} else if (group == "audio-app") {*policy = SP_AUDIO_APP;} else if (group == "custom") {*policy = SP_CUSTOM;} else {errno = ERANGE;return -1;}return 0;
}//修改get_sched_policy_name,添加SP_CUSTOM的处理
const char* get_sched_policy_name(SchedPolicy policy) {policy = _policy(policy);static const char* const kSchedPolicyNames[] = {[SP_BACKGROUND] = "bg", [SP_FOREGROUND] = "fg", [SP_SYSTEM] = " ",[SP_AUDIO_APP] = "aa", [SP_AUDIO_SYS] = "as", [SP_TOP_APP] = "ta",[SP_RT_APP] = "rt", [SP_RESTRICTED] = "rs",[SP_CUSTOM] = "ct",};static_assert(arraysize(kSchedPolicyNames) == SP_CNT, "missing name");if (policy < SP_BACKGROUND || policy >= SP_CNT) {return nullptr;}return kSchedPolicyNames[policy];
}//修改get_cpuset_policy_profile_name,添加SP_CUSTOM的处理
const char* get_cpuset_policy_profile_name(SchedPolicy policy) {/** cpuset profile array for:* SP_DEFAULT(-1), SP_BACKGROUND(0), SP_FOREGROUND(1),* SP_SYSTEM(2), SP_AUDIO_APP(3), SP_AUDIO_SYS(4),
- * SP_TOP_APP(5), SP_RT_APP(6), SP_RESTRICTED(7),
+ * SP_TOP_APP(5), SP_RT_APP(6), SP_RESTRICTED(7), SP_CUSTOM(8)* index is policy + 1* this need keep in sync with SchedPolicy enum*/static constexpr const char* kCpusetProfiles[SP_CNT + 1] = {"CPUSET_SP_DEFAULT", "CPUSET_SP_BACKGROUND", "CPUSET_SP_FOREGROUND","CPUSET_SP_SYSTEM", "CPUSET_SP_FOREGROUND", "CPUSET_SP_FOREGROUND",
- "CPUSET_SP_TOP_APP", "CPUSET_SP_DEFAULT", "CPUSET_SP_RESTRICTED"
+ "CPUSET_SP_TOP_APP", "CPUSET_SP_DEFAULT", "CPUSET_SP_RESTRICTED","CPUSET_SP_CUSTOM"};if (policy < SP_DEFAULT || policy >= SP_CNT) {return nullptr;}return kCpusetProfiles[policy + 1];
}//修改get_sched_policy_profile_name,添加SP_CUSTOM的处理
const char* get_sched_policy_profile_name(SchedPolicy policy) {/** sched profile array for:* SP_DEFAULT(-1), SP_BACKGROUND(0), SP_FOREGROUND(1),* SP_SYSTEM(2), SP_AUDIO_APP(3), SP_AUDIO_SYS(4),
- * SP_TOP_APP(5), SP_RT_APP(6), SP_RESTRICTED(7),
+ * SP_TOP_APP(5), SP_RT_APP(6), SP_RESTRICTED(7),SP_CUSTOM(8)* index is policy + 1* this need keep in sync with SchedPolicy enum*/static constexpr const char* kSchedProfiles[SP_CNT + 1] = {"SCHED_SP_DEFAULT", "SCHED_SP_BACKGROUND", "SCHED_SP_FOREGROUND","SCHED_SP_SYSTEM", "SCHED_SP_FOREGROUND", "SCHED_SP_FOREGROUND",
- "SCHED_SP_TOP_APP", "SCHED_SP_RT_APP", "SCHED_SP_DEFAULT"
+ "SCHED_SP_TOP_APP", "SCHED_SP_RT_APP", "SCHED_SP_DEFAULT","SCHED_SP_CUSTOM"};if (policy < SP_DEFAULT || policy >= SP_CNT) {return nullptr;}return kSchedProfiles[policy + 1];
}
以上2部分主要是逻辑的修改,接下来是配置文件的修改,在$AOSP/system/core/libprocessgroup/profiles/task_profiles.json文件中修改:
{"Attributes": [{"Name": "LowCapacityCPUs","Controller": "cpuset","File": "background/cpus"},...
+ {
+ "Name": "CustomCPUs",
+ "Controller": "cpuset",
+ "File": "custom/cpus"
+ },...{"Name": "FreezerState","Controller": "freezer","File": "cgroup.freeze"}],"Profiles": [{"Name": "HighEnergySaving","Actions": [{"Name": "JoinCgroup","Params":{"Controller": "cpu","Path": "background"}}]},...
+ {
+ "Name": "CustomPerformance",
+ "Actions" : [
+ {
+ "Name" : "JoinCgroup",
+ "Params" :
+ {
+ "Controller": "cpuset",
+ "Path": "custom"
+ }
+ }
+ ]
+ },...{"Name": "SystemMemoryProcess","Actions": [{"Name": "JoinCgroup","Params":{"Controller": "memory","Path": "system"}}]}],"AggregateProfiles": [{"Name": "SCHED_SP_DEFAULT","Profiles": [ "TimerSlackNormal" ]},...{"Name": "SCHED_SP_RT_APP","Profiles": [ "RealtimePerformance", "MaxIoPriority", "TimerSlackNormal" ]},
+ {
+ "Name": "SCHED_SP_CUSTOM",
+ "Profiles": [ "CUSTOMPerformance" ]
+ },...
+ {
+ "Name": "CPUSET_SP_CUSTOM",
+ "Profiles": [ "CUSTOMPerformance" ]
+ },...{"Name": "Dex2OatBootComplete","Profiles": [ "Dex2oatPerformance", "LowIoPriority", "TimerSlackHigh" ]}]
}
至此,system相关修改就结束了。主要是SP_CUSTOM相关逻辑的添加,配置文件task_profiles.json的修改,接口set_cpuset_policy和set_sched_policy的支持等。
2.2 init.rc及编译部分调整
为添加cpuset相关节点,需要修改init.rc文件,这里根据android源码的需要调整到对应的rc中添加即可。具体init.rc修改内容如下:
#第一部分:on init中添加:
...
+#custom add start
+ mkdir /dev/stune/custom
+ chown system system /dev/stune/custom
+ chown system system /dev/stune/custom/tasks
+ chmod 0664 /dev/stune/custom/tasks
+ mkdir /dev/cpuset/custom
+ copy /dev/cpuset/cpus /dev/cpuset/custom/cpus
+ copy /dev/cpuset/mems /dev/cpuset/custom/mems
+ chown system system /dev/cpuset/custom
+ chown system system /dev/cpuset/custom/tasks
+ chown system system /dev/cpuset/custom/cgroup.procs
+ chmod 0664 /dev/cpuset/custom/tasks
+ chmod 0664 /dev/cpuset/custom/cgroup.procs
+#custom add end
...
#第二部分:系统启动完成后添加:
+#custom add start
+on property:sys.boot_completed=1
+ write /dev/cpuset/custom/cpus 6-7
+ write /dev/cpuset/custom/mems 0
+#custom add end
这里主要是通过init.rc文件添加cpuset相关节点,以及修改cpuset相关节点的权限和owner,以及写入值操作。这样,在开机启动后就可以在/dev/cpuset/目录下看到自定义cpuset对应的custom节点。
至此代码和配置文件都已经修改完了。
接下来就需要编译了,但是编译这里要避免vndk报错的问题,需要有先执行如下脚本内容:
source build/envsetup.sh && lunch xxx
cd ./development/vndk/tools/header-checker/utils/
#这里的xxx一般是指out/target/product之后的路径
./create_reference_dumps.py -l libprocessgroup -product xxx
重新编译vndk,否则会出现如下类似的编译错误,如下所示:
error: VNDK library: XXX
******************************************************
error: Please update ABI references with: $ANDROID_BUILD_TOP/development/vndk/tools/header-checker/utils/create_reference_dumps.py -l libprocessgroup
ninja failed with: exit status 1
#### failed to build some targets ####