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1 原理說(shuō)明
這個(gè)方案有如下基本需求：
- 構(gòu)建自定義CPUSET，/dev/cpuset中包含一個(gè)全新的cpuset分組。且可以通過(guò)set_cpuset_policy和set_sched_policy接口可以設(shè)置自定義CPUSET。
- 開(kāi)機(jī)啟動(dòng)后可以通過(guò)zygote判定來(lái)對(duì)特定的應(yīng)用進(jìn)程設(shè)置CPUSET，并一直保持，且保證自定義CPUSET不受其他CPUSET影響，持續(xù)獨(dú)立。
原理上因?yàn)樾薷拇a涉及部分較多，因此共分3個(gè)部分：
- framework修改：添加SCHED GROUP和THREAD GROUP（THREAD_GROUP_對(duì)應(yīng)SP_）的支持，且支持開(kāi)機(jī)啟動(dòng)后直接設(shè)置。applyOomAdjLSP的判定保持不變。
- system修改：添加SP_CUSTOM的支持及set_cpuset_policy和set_sched_policy接口等支持，同時(shí)修改task_profiles.json，添加SP_CUSTOM CPUSET的支持。
- init.rc修改及編譯部分調(diào)整：對(duì)自定義cpuset節(jié)點(diǎn)進(jìn)行操作，vndk部分編譯需要重新調(diào)整方案以及不修改VNDK如何保證編譯通過(guò)。
由于修改中涉及代碼量過(guò)大，這里拆分成兩節(jié)進(jìn)行展示。本章節(jié)主要針對(duì)第2部分和第3部分修改進(jìn)行說(shuō)明。上一篇文章👇
Android Framework 常見(jiàn)解決方案（25-1）定制CPUSET解決方案-framework部分修改
主要對(duì)第1部分修改進(jìn)行說(shuō)明。
2 修改方案（Android S）
2.1 system部分修改
針對(duì)system分區(qū)修改。具體修改方案如下（這里以S版本修改為主，Q和R有一些差異但原理不變）：
在$AOSP/system/core/libprocessgroup/include/processgroup/sched_policy.h文件中修改：
/* Keep in sync with THREAD_GROUP_* in frameworks/base/core/java/android/os/Process.java */
typedef enum {SP_DEFAULT = -1,SP_BACKGROUND = 0,SP_FOREGROUND = 1,SP_SYSTEM = 2,SP_AUDIO_APP = 3,SP_AUDIO_SYS = 4,SP_TOP_APP = 5,SP_RT_APP = 6,SP_RESTRICTED = 7,
+ SP_CUSTOM = 8,SP_CNT,SP_MAX = SP_CNT - 1,SP_SYSTEM_DEFAULT = SP_FOREGROUND,
} SchedPolicy;這里注意，按照順序填寫(xiě)修改相對(duì)簡(jiǎn)單，因?yàn)楹罄m(xù)會(huì)用到SP_CNT和SP_MAX這兩個(gè)變量，代碼中還會(huì)有許多的遍歷操作，因此最好采用累加方案，不要設(shè)置其他值。
本方案的修改比較全面，即支持set_cpuset_policy，也兼容到set_sched_policy，在實(shí)際操作中，可根據(jù)需要只修改其中一個(gè)即可。
在$AOSP/system/core/libprocessgroup/sched_policy.cpp文件中修改：
//修改set_cpuset_policy，添加SP_CUSTOM的處理
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的處理
int set_sched_policy(int tid, SchedPolicy policy) {
//...
#if POLICY_DEBUG //注意：這一段的修改主要是調(diào)試使用，功能實(shí)現(xiàn)上可以不添加該部分
//...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的處理
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的處理
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_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的處理
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的處理
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部分主要是邏輯的修改，接下來(lái)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相關(guān)修改就結(jié)束了。主要是SP_CUSTOM相關(guān)邏輯的添加，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及編譯部分調(diào)整
?為添加cpuset相關(guān)節(jié)點(diǎn)，需要修改init.rc文件，這里根據(jù)android源碼的需要調(diào)整到對(duì)應(yīng)的rc中添加即可。具體init.rc修改內(nèi)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：系統(tǒng)啟動(dòng)完成后添加, 這里綁定的是456，可根據(jù)需要調(diào)整：
+#custom add start
+on property:sys.boot_completed=1
+ write /dev/cpuset/custom/cpus 4-6
+ write /dev/cpuset/custom/mems 0
+#custom add end這里主要是通過(guò)init.rc文件添加cpuset相關(guān)節(jié)點(diǎn)，以及修改cpuset相關(guān)節(jié)點(diǎn)的權(quán)限和owner，以及寫(xiě)入值操作。這樣，在開(kāi)機(jī)啟動(dòng)后就可以在/dev/cpuset/目錄下看到自定義cpuset對(duì)應(yīng)的custom節(jié)點(diǎn)。
至此代碼和配置文件都已經(jīng)修改完了。
接下來(lái)就需要編譯了，但是編譯這里要避免vndk報(bào)錯(cuò)的問(wèn)題，需要有先執(zhí)行如下腳本內(nèi)容：
source build/envsetup.sh && lunch xxx
cd ./development/vndk/tools/header-checker/utils/
#這里的xxx一般是指out/target/product之后的路徑
./create_reference_dumps.py -l libprocessgroup -product xxx重新編譯vndk，否則會(huì)出現(xiàn)如下類(lèi)似的編譯錯(cuò)誤，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 ####