专业网站开发哪家好,windows优化大师要钱,简述网站开发主要步骤,做网站pytonFtrace相关的文章如何利用ftrace精确跟踪特定进程调度信息1、Ftrace 是什么东西#xff1f;Ftrace是一个直接内置在Linux内核中的跟踪工具。许多发行版在最近的发行版中已经启用了各种各样的Ftrace配置。Ftrace给Linux带来的好处之一是能够看到内核中发生了什么。因此#xf… Ftrace相关的文章如何利用ftrace精确跟踪特定进程调度信息1、Ftrace 是什么东西Ftrace是一个直接内置在Linux内核中的跟踪工具。许多发行版在最近的发行版中已经启用了各种各样的Ftrace配置。Ftrace给Linux带来的好处之一是能够看到内核中发生了什么。因此这使得发现问题区域或简单地跟踪奇怪的bug变得更容易管理。上面那段话是直接翻译过来的原文如下我比较推荐大家直接看英文Ftrace is a tracing utility built directly into the Linux kernel. Many distributions already have various configurations of Ftrace enabled in their most recent releases. One of the benefits that Ftrace brings to Linux is the ability to see what is happening inside the kernel. As such, this makes finding problem areas or simply tracking down that strange bug more manageable.2、怎么使用Ftrace我的实验平台是MT8167、Linux4.4内核2.1、配置内核宏weiqifabsp-ubuntu1804:~/is10-sdk$ git diff kernel-4.4/
diff --git a/kernel-4.4/arch/arm/configs/xxx_defconfig
b/kernel-4.4/arch/arm/configs/xxx_defconfig
index 8da5210003..a88e53253f 100755
--- a/kernel-4.4/arch/arm/configs/xxx_defconfigb/kernel-4.4/arch/arm/configs/xxx_defconfig-400,3 400,7 CONFIG_USB_RTL8152yCONFIG_USB_NET_DRIVERSyCONFIG_GPIO_CONTROLy#CONFIG_POGO_PINy
CONFIG_FUNCTION_TRACERy
CONFIG_FUNCTION_GRAPH_TRACERy
CONFIG_STACK_TRACERy
CONFIG_DYNAMIC_FTRACEy
2.2、烧录boot.img 重新开机2.3、查看是否生效进入ftrace 目录xxx:/ # cd /sys/kernel/debug/tracing
xxx:/sys/kernel/debug/tracing # ls
README enabled_functions saved_cmdlines set_graph_function trace_marker
available_events events saved_cmdlines_size set_graph_notrace trace_options
available_filter_functions free_buffer saved_tgids snapshot trace_pipe
available_tracers instances set_event stack_max_size tracing_cpumask
buffer_size_kb max_graph_depth set_event_pid stack_trace tracing_max_latency
buffer_total_size_kb options set_ftrace_filter stack_trace_filter tracing_on
current_tracer per_cpu set_ftrace_notrace trace tracing_thresh
dyn_ftrace_total_info printk_formats set_ftrace_pid trace_clock
xxx:/sys/kernel/debug/tracing #
查看内核支持的跟踪器列表xxx:/sys/kernel/debug/tracing # cat available_tracers
function_graph function nop
xxx:/sys/kernel/debug/tracing #
Tracer有很多种主要几大类函数类function function_graph stack延时类irqsoff preemptoff preemptirqsoff wakeup wakeup_rt waktup_dl其他类nop mmiotrace blk使能function_graph跟踪器echo function_graph current_tracer
查看当前的跟踪器xxx:/sys/kernel/debug/tracing # cat current_tracer
function_graph
xxx:/sys/kernel/debug/tracing #
使能ftrace 功能xxx:/sys/kernel/debug/tracing # echo 1 tracing_on
查看ftrace输出1|Knowin inSight10:/sys/kernel/debug/tracing # cat trace | head -40
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |2) 4.000 us | } /* path_init */2) | link_path_walk() {2) | inode_permission2() {2) | __inode_permission2() {2) | generic_permission() {2) 0.384 us | in_group_p();2) 2.154 us | }2) | security_inode_permission() {2) | selinux_inode_permission() {2) 0.231 us | __rcu_read_lock();2) 0.308 us | avc_lookup();2) 0.231 us | __rcu_read_unlock();2) 5.923 us | }2) 7.846 us | }2) 13.538 us | }2) 15.308 us | }2) | walk_component() {2) | lookup_fast() {2) 0.307 us | __d_lookup_rcu();2) 0.307 us | __lookup_mnt();2) 4.231 us | }2) 6.077 us | }2) | inode_permission2() {2) | __inode_permission2() {3) 3.923 us | } /* down_trylock */2) | generic_permission() {3) 6.538 us | } /* console_trylock */2) 0.308 us | in_group_p();3) | console_unlock() {3) 0.231 us | _raw_spin_lock_irqsave();2) 2.231 us | }2) | security_inode_permission() {2) | selinux_inode_permission() {3) 0.308 us | _raw_spin_unlock_irqrestore();2) 0.231 us | __rcu_read_lock();3) 0.231 us | _raw_spin_lock_irqsave();
Knowin inSight10:/sys/kernel/debug/tracing #
3、Ftrace 其他使用特点直接cat trace 文件内容太多了我们可以通过设置filter来设置过滤函数。为了方便使用set_ftrace_filter 文件还支持简单格式的通配符。value* 选择所有名字以 value字串开头的函数*value* 选择所有名字中包含 value字串的函数*value 选择所有名字以 value字串结尾的函数设置filterxxx:/sys/kernel/debug/tracing # echo raw* set_ftrace_filter
xxx:/sys/kernel/debug/tracing #
再查看trace文件xxx:/sys/kernel/debug/tracing # cat trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |2) 1.693 us | raw_local_deliver();2) 0.308 us | raw_local_deliver();2) 1.000 us | raw_notifier_call_chain();2) 2.077 us | raw_notifier_call_chain();2) 1.923 us | raw_local_deliver();------------------------------------------2) ntloop--1393 ...-16------------------------------------------2) 0.308 us | raw_local_deliver();------------------------------------------2) ...-16 idle-0------------------------------------------2) 0.307 us | raw_notifier_call_chain();2) 0.846 us | raw_notifier_call_chain();2) 0.385 us | raw_notifier_call_chain();------------------------------------------2) idle-0 droid.b-4348------------------------------------------2) 1.000 us | raw_notifier_call_chain();2) 1.384 us | raw_notifier_call_chain();------------------------------------------2) droid.b-4348 Binder:-524------------------------------------------2) 0.923 us | raw_notifier_call_chain();2) 1.077 us | raw_notifier_call_chain();------------------------------------------2) Binder:-524 droid.b-4348------------------------------------------2) 1.000 us | raw_notifier_call_chain();------------------------------------------2) droid.b-4348 Binder:-524------------------------------------------2) 1.231 us | raw_notifier_call_chain();------------------------------------------2) Binder:-524 droid.b-4348------------------------------------------2) 1.077 us | raw_notifier_call_chain();2) 1.692 us | raw_notifier_call_chain();2) 2.000 us | raw_notifier_call_chain();2) 1.000 us | raw_notifier_call_chain();2) 0.923 us | raw_notifier_call_chain();2) 0.462 us | raw_notifier_call_chain();2) 1.000 us | raw_notifier_call_chain();2) 0.846 us | raw_notifier_call_chain();
查看中间字符串xxx:/sys/kernel/debug/tracing # echo *touch* set_ftrace_filter
查看tracexxx:/sys/kernel/debug/tracing # cat trace |head -40
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |0) | /* 6 [cpu_loading] not_reset_cpu_loading */0) | /* 6 [cpu_loading] update cpu_loading */0) | /* 6 [cpu_loading] cur_idle_time[0].time:933317139 cur_wall_time[0].time:1008009932*/0) | /* 6 [cpu_loading] cur_idle_time[1].time:936071150 cur_wall_time[1].time:1008009942*/0) | /* 6 [cpu_loading] cur_idle_time[2].time:917091836 cur_wall_time[2].time:1008009946*/0) | /* 6 [cpu_loading] cur_idle_time[3].time:890438730 cur_wall_time[3].time:1008009950*/0) | /* 6 [cpu_loading] cur_idle_time[0].time:933317139 cur_wall_time[0].time:1008009932*/0) | /* 6 [cpu_loading] cur_idle_time[1].time:936071150 cur_wall_time[1].time:1008009942*/0) | /* 6 [cpu_loading] cur_idle_time[2].time:917091836 cur_wall_time[2].time:1008009946*/0) | /* 6 [cpu_loading] cur_idle_time[3].time:890438730 cur_wall_time[3].time:1008009950*/0) | /* 6 [cpu_loading] tmp_cpu_loading:2 prev_cpu_loading:1 previous state:3*/0) | /* 6 [cpu_loading] sent uevent success:lower2 */0) | /* 6 [cpu_loading] current state:3*/0) | /* 6 [cpu_loading] enable timer */1) 1.462 us | touch_atime();1) 0.616 us | touch_atime();1) 0.385 us | touch_atime();1) 0.538 us | touch_atime();1) 0.539 us | touch_atime();1) 1.461 us | touch_atime();1) 0.308 us | touch_atime();1) 0.385 us | touch_atime();1) 0.385 us | touch_atime();1) 2.000 us | touch_atime();1) 0.923 us | touch_atime();1) 0.615 us | touch_atime();
xxx:/sys/kernel/debug/tracing #
通过该文件还可以指定属于特定模块的函数这要用到 mod 指令。指定模块的格式为echo :mod:[module_name] set_ftrace_filter
查看对应的内核模块xxx:/sys/kernel/debug/tracing # cat /proc/devices
Character devices:1 mem2 pty3 ttyp4 ttyS5 /dev/tty5 /dev/console5 /dev/ptmx10 misc13 input14 sound29 fb
使用过滤器只针对某个模块进行跟踪xxx:/sys/kernel/debug/tracing # echo :mod:sound set_ftrace_filter
1|xxx:/sys/kernel/debug/tracing #
需要注意的是这三种形式不能组合使用比如“beginmiddleend”实际的效果与“begin”相同。另外使用通配符表达式时需要用单引号将其括起来如果使用双引号shell 可能会对字符‘ * ’进行扩展这样最终跟踪的对象可能与目标函数不一样。4.参考资料[1]、 https://lwn.net/Articles/365835/[2]、https://www.kernel.org/doc/Documentation/trace/ftrace.txt推荐阅读专辑|Linux文章汇总专辑|程序人生专辑|C语言我的知识小密圈
