Dtrace 快速参考

传统的系统观测工具，truss, iostat, mpstat, cpustat, vmstat, lockstat,proc(1)等可以实现对单个子系统的监测。DTrace 不仅可以实现这些工具的功能，还具备了更强大的能力，从应用程序进程，到操作系统内核；从宏观的模块性能，到具体每个函数的使用、运行情况，甚至到每个指 令的执行过程，DTrace都可以对其进行跟踪。DTrace为系统性能监测，程序开发调试等提供了一个统一的接口。

DTrace probe的基本结构：
provider:module:function:name
/predicate/
{
    /*action*/
}

dtrace -l  -- list all probes
dtrace -l -f function -- list probe function
dtrace -l -m module -- list probe module
dtrace -l -n  name    -- list probe name
dtrace -l -P provider  -- list probe provider

1. 常用D变量（内置）：

int64_t arg0, ..., arg9

The first ten input arguments to a probe represented as raw 64-bit integers. If fewer than ten arguments are passed to the current probe, the remaining variables return zero.

args[]

The typed arguments to the current probe, if any. The args[] array is accessed using an integer index, but each element is defined to be the type corresponding to the given probe argument. For example, if the args[] array is referenced by a read(2) system call probe, args[0] is of type int, args[1] is of type void *, and args[2] is of type size_t.

uintptr_t caller

The program counter location of the current thread just before entering the current probe.

chipid_t chip

The CPU chip identifier for the current physical chip.

processorid_t cpu

The CPU identifier for the current CPU.

cpuinfo_t *curcpu

The CPU information for the current CPU.

lwpsinfo_t *curlwpsinfo

The lightweight process (LWP) state of the LWP associated with the current thread. This structure is described in further detail in the proc(4) man page.

psinfo_t *curpsinfo

The process state of the process associated with the current thread. This structure is described in further detail in the This structure is described in further detail in the proc(4) man page.

kthread_t *curthread

The address of the operating system kernel's internal data structure for the current thread, the kthread_t. The kthread_t is defined in <sys/thread.h>. Refer to Solaris Internals for more information on this variable and other operating system data structures.

string cwd

The name of the current working directory of the process associated with the current thread.

uint_t epid

The enabled probe ID (EPID) for the current probe. This integer uniquely identifiers a particular probe that is enabled with a specific predicate and set of actions.

int errno

The error value returned by the last system call executed by this thread.

string execname

The name that was passed to exec(2) to execute the current process.

gid_t gid

The real group ID of the current process.

uint_t id

The probe ID for the current probe. This ID is the system-wide unique identifier for the probe as published by DTrace and listed in the output of dtrace -l.

uint_t ipl

The interrupt priority level (IPL) on the current CPU at the time that the probe fires. Refer to Solaris Internals for more information on interrupt levels and interrupt handling in the Solaris operating system kernel.

lgrp_id_t lgrp

The locality group ID for the latency group of which the current CPU is a member.

pid_t pid

The process ID of the current process.

pid_t ppid

The parent process ID of the current process.

string probefunc

The function name portion of the current probe's description.

string probemod

The module name portion of the current probe's description.

string probename

The name portion of the current probe's description.

string probeprov

The provider name portion of the current probe's description.

psetid_t pset

The processor set ID for the processor set that contains the current CPU.

string root

The name of the root directory of the process associated with the current thread.

uint_t stackdepth

The current thread's stack frame depth at probe firing time.

id_t tid

The thread ID of the current thread. For threads that are associated with user processes, this value is equal to the result of a call to pthread_self(3C).

uint64_t timestamp

The current value of a nanosecond timestamp counter. This counter increments from an arbitrary point in the past and should only be used for relative computations.

uid_t uid

The real user ID of the current process.

uint64_t uregs[]

The current thread's saved user-mode register values at probe firing time. Use of the uregs[] array is discussed in Chapter 33, User Process Tracing, in Solaris Dynamic Tracing Guide.

uint64_t vtimestamp

The current value of a nanosecond timestamp counter. The counter is virtualized to the amount of time that the current thread has been running on a CPU. The counter does not include the time that is spent in DTrace predicates and actions. This counter increments from an arbitrary point in the past and should only be used for relative time computations.

uint64_t walltimestamp

The current number of nanoseconds since 00:00 Universal Coordinated Time, January 1, 1970.

例：

# dtrace -n 'zfod {trace(pid);trace(execname)}'

2. Aggregation

@name[ keys ] = aggfunc( args );

aggfunc: count(),sum,avg,min,max,lquantize,quantize

3.常用 D Macros:

$[0-9]+

Macro arguments

$egid

Effective group-ID

$euid

Effective user-ID

$gid

Real group-ID

$pid

Process ID

$pgid

Process group ID

$ppid

Parent process ID

$projid

Project ID

$sid

Session ID

$target

Target process ID

$taskid

Task ID

$uid

Real user-ID

变量pid与 macro $pid的区别：

syscall::write:entry
/pid != $pid/
{
	printf("%s", stringof(copyin(arg1, arg2)));
}

The $pid macro variable expands to the process identifier of the process that enabled the probes. The pid variable contains the process identifier of the process whose thread was running on the CPU where the probe was fired. The predicate /pid != $pid/ ensures that the script does not trace any events related to the running of this script.

http://docs.sun.com/app/docs/doc/819-5488

http://developers.sun.com/solaris/articles/dtrace_quickref/dtrace_quickref.html

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