Systrace实现-1-判断Trace是否使能
基于A12
一、isTagEnabled()执行逻辑
这里以binder的 isTagEnabled() 为例进行说明。
相关文件：
android/frameworks/base/core/java/android/os/Binder.java android/frameworks/base/core/java/android/os/Trace.java android/frameworks/base/core/jni/android_os_Trace.cpp android/system/core/libcutils/trace-dev.inc android/bionic/libc/bionic/system_property_api.cpp
1. Java执行流
execTransactInternal //Binder.java if (Binder.isTracingEnabled()) //可有可无 Trace.traceBegin(Trace.TRACE_TAG_ALWAYS, getClass().getName() + ":" transactionName);
xxx
Trace.traceEnd(Trace.TRACE_TAG_ALWAYS);
下面看 Trace.traceBegin() 是如何实现的:
public static void traceBegin(long traceTag, String methodName) { //Trace.java if (isTagEnabled(traceTag)) { //不抓trace时主要看它是否影响性能 nativeTraceBegin(traceTag, methodName); } } public static boolean isTagEnabled(long traceTag) { //Trace.java long tags = nativeGetEnabledTags(); return (tags & traceTag) != 0; } static const JNINativeMethod gTraceMethods[] = { //android_os_Trace.cpp { "nativeGetEnabledTags", "()J", (void*)atrace_get_enabled_tags }, uint64_t atrace_get_enabled_tags() //trace-dev.inc { atrace_init(); return atrace_enabled_tags; } /* 正常不抓trace时，这里应该就读一下就退出了 */ void atrace_init() { //trace-dev.inc #if defined(__BIONIC__) //它也是读取一个变量 uint32_t seq_no = __system_property_serial(atrace_property_info); //Acquire semantics. #else uint32_t seq_no = 0; #endif uint32_t prev_seq_no = atomic_load_explicit(&last_sequence_number, memory_order_relaxed); if (CC_UNLIKELY(seq_no != prev_seq_no)) { atrace_seq_number_changed(prev_seq_no, seq_no); } } uint32_t __system_property_serial(const prop_info* pi) { //system_property_api.cpp return atomic_load_explicit(&pi->serial, memory_order_acquire); } static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no) { if (!atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) { return; } if (!atomic_compare_exchange_strong(&last_sequence_number, &prev_seq_no, seq_no)) { return; } if (CC_UNLIKELY(prev_seq_no == kSeqNoNotInit)) { #if defined(__BIONIC__) const prop_info* new_pi = __system_property_find("debug.atrace.tags.enableflags"); if (new_pi) atrace_property_info = new_pi; #endif pthread_once(&atrace_once_control, atrace_init_once); } atrace_update_tags(); } void atrace_update_tags() //trace-dev.inc { uint64_t tags; if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) { tags = atrace_get_property(); pthread_mutex_lock(&atrace_tags_mutex); atrace_enabled_tags = tags; pthread_mutex_unlock(&atrace_tags_mutex); } else { /* 此进程的跟踪已被禁用，因此我们不初始化标签 */ pthread_mutex_lock(&atrace_tags_mutex); atrace_enabled_tags = ATRACE_TAG_NOT_READY; pthread_mutex_unlock(&atrace_tags_mutex); } } /* Read the sysprop and return the value tags should be set to */ static uint64_t atrace_get_property() //trace-dev.inc { char value[PROPERTY_VALUE_MAX]; char *endptr; uint64_t tags; property_get("debug.atrace.tags.enableflags", value, "0"); ###### tags = strtoull(value, &endptr, 0); /* 仅当选择此进程进行应用程序级调试跟踪时才设置"app"标签 */ if (atrace_is_app_tracing_enabled()) { tags |= ATRACE_TAG_APP; } else { tags &= ~ATRACE_TAG_APP; } return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK; } /* 确定是否为此进程启用了应用程序级跟踪。 */ static bool atrace_is_app_tracing_enabled() //trace-dev.inc { bool sys_debuggable = property_get_bool("ro.debuggable", 0); bool result = false; if (sys_debuggable || atrace_is_debuggable) { /* Check whether tracing is enabled for this process. */ FILE * file = fopen("/proc/self/cmdline", "re"); if (file) { if (fgets(cmdline, sizeof(cmdline), file)) { result = atrace_is_cmdline_match(cmdline); } fclose(file); } return result; } /* 检查给定的命令行是否与 app_cmdlines 属性中列出的逗号分隔的值之一匹配 */ static bool atrace_is_cmdline_match(const char* cmdline) //trace-dev.inc { int count = property_get_int32("debug.atrace.app_number", 0); char buf[PROPERTY_KEY_MAX]; char value[PROPERTY_VALUE_MAX]; for (int i = 0; i < count; i++) { snprintf(buf, sizeof(buf), "debug.atrace.app_%d", i); property_get(buf, value, ""); if (strcmp(value, "*") == 0 || strcmp(value, cmdline) == 0) { return true; } } return false; }
"ro.debuggable" userdebug 版本是1，user 版本是0.
若是正常不抓systrace的时候，Trace.traceBegin() 对性能的影响应该就是一次JNI调用 + 一次原子变量的读取。
2. atrace_is_debuggable 是如何赋值的
void atrace_set_debuggable(bool debuggable) //trace-dev.inc { atrace_is_debuggable = debuggable; atrace_update_tags(); } static void android_os_Trace_nativeSetAppTracingAllowed(JNIEnv*, jclass, jboolean allowed) { //android_os_Trace.cpp atrace_set_debuggable(allowed); } static const JNINativeMethod gTraceMethods[] = { { "nativeSetAppTracingAllowed", "(Z)V", (void*)android_os_Trace_nativeSetAppTracingAllowed }, } public static void setAppTracingAllowed(boolean allowed) { //Trace.java nativeSetAppTracingAllowed(allowed); } //android/frameworks/base/core/java/android/app/ActivityThread.java private void handleBindApplication(AppBindData data) { /* 如果我们 profileable 的话，允许 Binder trace和应用程序生成的 systrace 消息。 */ boolean isAppDebuggable = (data.appInfo.flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0; boolean isAppProfileable = isAppDebuggable || data.appInfo.isProfileable(); Trace.setAppTracingAllowed(isAppProfileable); //唯一调用位置 if ((isAppProfileable || Build.IS_DEBUGGABLE) && data.enableBinderTracking) { Binder.enableTracing(); //还有可能使能binder trace } }
在 handleBindApplication() 中使能。
3. ATRACE_TAG_APP 谁在用
全局检索 ATRACE_TAG_APP 只有下面这个文件中使用了这个TAG.
//android/frameworks/base/native/android/trace.cpp
但是在系统中检索这里面实现的函数，几乎没有调用位置。
二、trace相关属性
1. trace属性值
/ # getprop | grep trace [debug.atrace.app_0]: [] //ro.debuggable为true时不存在，应该只user版本用 [debug.atrace.app_number]: [] //ro.debuggable为true时不存在，应该只user版本用 [debug.atrace.tags.enableflags]: [0] //不抓trace时是0，抓trace时是 0x496e [debug.atrace.user_initiated]: [] //ro.debuggable为true时不存在，应该只user版本用 [init.svc.traced]: [running] //抓不抓trace都恒为running，TODO: 这个traced服务是谁呀？ [init.svc.traced_perf]: [stopped] //抓不抓trace都恒为stopped [init.svc.traced_probes]: [running] //抓trace时是stopped，停止抓取时是running [init.svc.vendor.atrace-hal-1-0]: [running] //恒为running, TODO: 是 atrace@1.0-serv 吗？看它是做什么的？ [init.svc_debug_pid.traced]: [991] [init.svc_debug_pid.traced_perf]: [] [init.svc_debug_pid.traced_probes]: [988] //这个会变 [init.svc_debug_pid.vendor.atrace-hal-1-0]: [486] [persist.debug.trace]: [0] [persist.traced.enable]: [1] [ro.boottime.traced]: [5760607183] [ro.boottime.traced_probes]: [5737517444] [ro.boottime.vendor.atrace-hal-1-0]: [4075050727]
当使能 ro.debuggable 后，debug.atrace.app_0、debug.atrace.app_number、debug.atrace.user_initiated 就都不存在了。
抓trace时，在默认的配置下 debug.atrace.tags.enableflags 属性的值是 0x496e(0b0100,1001,0110,1110) 对应 atrace 抓取命令的使能项 "gfx input view wm am sched idle freq irq disk workq binder_driver binder_lock audio dalvik hal"
这些值是与 /android/system/core/libcutils/include/cutils/trace.h 里面的定义是对应的:
//android/system/core/libcutils/include/cutils/trace.h //0x496e = 0b0100,1001,0110,1101 = #define ATRACE_TAG_GRAPHICS (1<<1) //对应"gfx" #define ATRACE_TAG_INPUT (1<<2) //对应"input" #define ATRACE_TAG_VIEW (1<<3) //对应"view" #define ATRACE_TAG_WINDOW_MANAGER (1<<5) //对应"wm" #define ATRACE_TAG_ACTIVITY_MANAGER (1<<6) //对应"am" #define ATRACE_TAG_AUDIO (1<<8) //对应"audio" #define ATRACE_TAG_HAL (1<<11) //对应"hal" #define ATRACE_TAG_DALVIK (1<<14) //对应"dalvik"
atrace增加一个 "aidl" 项后是 0x100496e, 多出 1<<24, 刚好是 ATRACE_TAG_AIDL 的值。
[debug.atrace.tags.enableflags]: [0x100496e]
#define ATRACE_TAG_AIDL (1<<24)
2. ro.debuggable 属性
Android系统中 ro.debuggable 属性的初始化逻辑主要分为以下三个阶段：
(1) 编译阶段固化
ro.debuggable 的初始值在 Android 系统编译时由 build.prop 或 default.prop 文件设定，具体取决于设备厂商的配置。例如：
a. 普通用户版 ROM 通常设为 0（禁止全局调试）；
b. 开发版或模拟器镜像可能预设为 1（允许全局调试）。
(2) 启动阶段加载
Android 启动时，init 进程会从 boot.img 的 ramdisk 挂载分区，读取 default.prop 并加载所有系统属性（包括 ro.debuggable）。一旦 init 进程完成初始化，ro.debuggable 会被标记为只读（read-only），普通方法无法修改。
实测 ro.debuggable 位于机器中的 /default.prop 文件中。实测改为1后再push到机器中，无论是执行 stop/start，还是 reboot 都不会改变其值。
三、atrace选项与TAG的对应关系
每一个 TAG 与 atrace 选项的对应关系见 k_categories[]
//android/frameworks/native/cmds/atrace/atrace.cpp /* Tracing categories */ static const TracingCategory k_categories[] = { { "gfx", "Graphics", ATRACE_TAG_GRAPHICS, { { OPT, "events/gpu_mem/gpu_mem_total/enable" }, } }, { "input", "Input", ATRACE_TAG_INPUT, { } }, { "view", "View System", ATRACE_TAG_VIEW, { } }, { "webview", "WebView", ATRACE_TAG_WEBVIEW, { } }, { "wm", "Window Manager", ATRACE_TAG_WINDOW_MANAGER, { } }, { "am", "Activity Manager", ATRACE_TAG_ACTIVITY_MANAGER, { } }, { "sm", "Sync Manager", ATRACE_TAG_SYNC_MANAGER, { } }, { "audio", "Audio", ATRACE_TAG_AUDIO, { } }, { "video", "Video", ATRACE_TAG_VIDEO, { } }, { "camera", "Camera", ATRACE_TAG_CAMERA, { } }, { "hal", "Hardware Modules", ATRACE_TAG_HAL, { } }, { "res", "Resource Loading", ATRACE_TAG_RESOURCES, { } }, { "dalvik", "Dalvik VM", ATRACE_TAG_DALVIK, { } }, { "rs", "RenderScript", ATRACE_TAG_RS, { } }, { "bionic", "Bionic C Library", ATRACE_TAG_BIONIC, { } }, { "power", "Power Management", ATRACE_TAG_POWER, { } }, { "pm", "Package Manager", ATRACE_TAG_PACKAGE_MANAGER, { } }, { "ss", "System Server", ATRACE_TAG_SYSTEM_SERVER, { } }, { "database", "Database", ATRACE_TAG_DATABASE, { } }, { "network", "Network", ATRACE_TAG_NETWORK, { } }, { "adb", "ADB", ATRACE_TAG_ADB, { } }, { "vibrator", "Vibrator", ATRACE_TAG_VIBRATOR, { } }, { "aidl", "AIDL calls", ATRACE_TAG_AIDL, { } }, { "nnapi", "NNAPI", ATRACE_TAG_NNAPI, { } }, { "rro", "Runtime Resource Overlay", ATRACE_TAG_RRO, { } }, { k_coreServiceCategory, "Core services", 0, { } }, { k_pdxServiceCategory, "PDX services", 0, { } }, { "sched", "CPU Scheduling", 0, { { REQ, "events/sched/sched_switch/enable" }, { REQ, "events/sched/sched_wakeup/enable" }, { OPT, "events/sched/sched_waking/enable" }, { OPT, "events/sched/sched_blocked_reason/enable" }, { OPT, "events/sched/sched_cpu_hotplug/enable" }, { OPT, "events/sched/sched_pi_setprio/enable" }, { OPT, "events/sched/sched_process_exit/enable" }, { OPT, "events/cgroup/enable" }, { OPT, "events/oom/oom_score_adj_update/enable" }, { OPT, "events/task/task_rename/enable" }, { OPT, "events/task/task_newtask/enable" }, } }, { "irq", "IRQ Events", 0, { { REQ, "events/irq/enable" }, { OPT, "events/ipi/enable" }, } }, { "irqoff", "IRQ-disabled code section tracing", 0, { { REQ, "events/preemptirq/irq_enable/enable" }, { REQ, "events/preemptirq/irq_disable/enable" }, } }, { "preemptoff", "Preempt-disabled code section tracing", 0, { { REQ, "events/preemptirq/preempt_enable/enable" }, { REQ, "events/preemptirq/preempt_disable/enable" }, } }, { "i2c", "I2C Events", 0, { { REQ, "events/i2c/enable" }, { REQ, "events/i2c/i2c_read/enable" }, { REQ, "events/i2c/i2c_write/enable" }, { REQ, "events/i2c/i2c_result/enable" }, { REQ, "events/i2c/i2c_reply/enable" }, { OPT, "events/i2c/smbus_read/enable" }, { OPT, "events/i2c/smbus_write/enable" }, { OPT, "events/i2c/smbus_result/enable" }, { OPT, "events/i2c/smbus_reply/enable" }, } }, { "freq", "CPU Frequency", 0, { { REQ, "events/power/cpu_frequency/enable" }, { OPT, "events/power/clock_set_rate/enable" }, { OPT, "events/power/clock_disable/enable" }, { OPT, "events/power/clock_enable/enable" }, { OPT, "events/clk/clk_set_rate/enable" }, { OPT, "events/clk/clk_disable/enable" }, { OPT, "events/clk/clk_enable/enable" }, { OPT, "events/power/cpu_frequency_limits/enable" }, { OPT, "events/power/suspend_resume/enable" }, { OPT, "events/cpuhp/cpuhp_enter/enable" }, { OPT, "events/cpuhp/cpuhp_exit/enable" }, { OPT, "events/cpuhp/cpuhp_pause/enable" }, } }, { "membus", "Memory Bus Utilization", 0, { { REQ, "events/memory_bus/enable" }, } }, { "idle", "CPU Idle", 0, { { REQ, "events/power/cpu_idle/enable" }, } }, { "disk", "Disk I/O", 0, { { OPT, "events/f2fs/f2fs_sync_file_enter/enable" }, { OPT, "events/f2fs/f2fs_sync_file_exit/enable" }, { OPT, "events/f2fs/f2fs_write_begin/enable" }, { OPT, "events/f2fs/f2fs_write_end/enable" }, { OPT, "events/ext4/ext4_da_write_begin/enable" }, { OPT, "events/ext4/ext4_da_write_end/enable" }, { OPT, "events/ext4/ext4_sync_file_enter/enable" }, { OPT, "events/ext4/ext4_sync_file_exit/enable" }, { REQ, "events/block/block_rq_issue/enable" }, { REQ, "events/block/block_rq_complete/enable" }, } }, { "mmc", "eMMC commands", 0, { { REQ, "events/mmc/enable" }, } }, { "load", "CPU Load", 0, { { REQ, "events/cpufreq_interactive/enable" }, } }, { "sync", "Synchronization", 0, { // linux kernel < 4.9 { OPT, "events/sync/enable" }, // linux kernel == 4.9.x { OPT, "events/fence/enable" }, // linux kernel > 4.9 { OPT, "events/dma_fence/enable" }, } }, { "workq", "Kernel Workqueues", 0, { { REQ, "events/workqueue/enable" }, } }, { "memreclaim", "Kernel Memory Reclaim", 0, { { REQ, "events/vmscan/mm_vmscan_direct_reclaim_begin/enable" }, { REQ, "events/vmscan/mm_vmscan_direct_reclaim_end/enable" }, { REQ, "events/vmscan/mm_vmscan_kswapd_wake/enable" }, { REQ, "events/vmscan/mm_vmscan_kswapd_sleep/enable" }, { OPT, "events/lowmemorykiller/enable" }, } }, { "regulators", "Voltage and Current Regulators", 0, { { REQ, "events/regulator/enable" }, } }, { "binder_driver", "Binder Kernel driver", 0, { { REQ, "events/binder/binder_transaction/enable" }, { REQ, "events/binder/binder_transaction_received/enable" }, { REQ, "events/binder/binder_transaction_alloc_buf/enable" }, { OPT, "events/binder/binder_set_priority/enable" }, } }, { "binder_lock", "Binder global lock trace", 0, { { OPT, "events/binder/binder_lock/enable" }, { OPT, "events/binder/binder_locked/enable" }, { OPT, "events/binder/binder_unlock/enable" }, } }, { "pagecache", "Page cache", 0, { { REQ, "events/filemap/enable" }, } }, { "memory", "Memory", 0, { { OPT, "events/mm_event/mm_event_record/enable" }, { OPT, "events/kmem/rss_stat/enable" }, { OPT, "events/kmem/ion_heap_grow/enable" }, { OPT, "events/kmem/ion_heap_shrink/enable" }, { OPT, "events/ion/ion_stat/enable" }, { OPT, "events/gpu_mem/gpu_mem_total/enable" }, } }, { "thermal", "Thermal event", 0, { { REQ, "events/thermal/thermal_temperature/enable" }, { OPT, "events/thermal/cdev_update/enable" }, } }, };
注: REQ 是必须要使能的，若写失败会返回false, 而 OPT 可选使能的, 即使不能写或写失败也不报错。
posted on 2025-03-27 17:35 Hello-World3 阅读(110) 评论(0) 收藏 举报
浙公网安备 33010602011771号