Solaris Dynamic Tracing Guide


Several proc probes have arguments of type lwpsinfo_t, a structure that is documented in proc(4). The definition of the lwpsinfo_t structure as available to DTrace consumers is as follows:

typedef struct lwpsinfo {
	int pr_flag;              /* flags; see below */
	id_t pr_lwpid;            /* LWP id */
	uintptr_t pr_addr;        /* internal address of thread */
	uintptr_t pr_wchan;       /* wait addr for sleeping thread */
	char pr_stype;            /* synchronization event type */
	char pr_state;            /* numeric thread state */
	char pr_sname;            /* printable character for pr_state */
	char pr_nice;             /* nice for cpu usage */
	short pr_syscall;         /* system call number (if in syscall) */
	int pr_pri;               /* priority, high value = high priority */
	char pr_clname[PRCLSZ];   /* scheduling class name */
	processorid_t pr_onpro;   /* processor which last ran this thread */
	processorid_t pr_bindpro; /* processor to which thread is bound */
	psetid_t pr_bindpset;     /* processor set to which thread is bound */
} lwpsinfo_t;

The pr_flag field is a bit-mask holding flags describing the process. These flags and their meanings are described in Table 25–3.

Table 25–3 pr_flag Values


The process is a system process. 


The process is the parent of a vfork(2)'d child.


The process has its inherit-on-fork mode set. 


The process has its run-on-last-close mode set. 


The process has its kill-on-last-close mode set. 


The process has its asynchronous-stop mode set. 


The process has microstate accounting enabled. 


The process microstate accounting is inherited on fork. 


The process has its breakpoint adjustment mode set. 


The process has its ptrace(3C)-compatibility mode set.


The thread is an LWP that is stopped. 


The thread is an LWP stopped on an event of interest. 


The thread is an LWP that has a stop directive in effect. 


The thread is an LWP that has a single-step directive in effect. 


The thread is an LWP in an interruptible sleep within a system call. 


The thread is a detached LWP. See pthread_create(3C) and pthread_join(3C).


The thread is a daemon LWP. See pthread_create(3C).


The thread is the agent LWP for the process. 


The thread is the idle thread for a CPU. Idle threads only run on a CPU when the run queues for the CPU are empty. 

The pr_addr field is the address of a private, in-kernel data structure representing the thread. While the data structure is private, the pr_addr field may be used as a token unique to a thread for the thread's lifetime.

The pr_wchan field is set when the thread is sleeping on a synchronization object. The meaning of the pr_wchan field is private to the kernel implementation, but the field may be used as a token unique to the synchronization object.

The pr_stype field is set when the thread is sleeping on a synchronization object. The possible values for the pr_stype field are in Table 25–4.

Table 25–4 pr_stype Values


Kernel mutex synchronization object. Used to serialize access to shared data regions in the kernel. See Chapter 18, lockstat Provider and mutex_init(9F) for details on kernel mutex synchronization objects.


Kernel readers/writer synchronization object. Used to synchronize access to shared objects in the kernel that can allow multiple concurrent readers or a single writer. See Chapter 18, lockstat Provider and rwlock(9F) for details on kernel readers/writer synchronization objects.


Condition variable synchronization object. A condition variable is designed to wait indefinitely until some condition becomes true. Condition variables are typically used to synchronize for reasons other than access to a shared data region, and are the mechanism generally used when a process performs a program-directed indefinite wait. For example, blocking in poll(2), pause(2), wait(3C), and the like.


Semaphore synchronization object. A general-purpose synchronization object that – like condition variable objects – does not track a notion of ownership. Because ownership is required to implement priority inheritance in the Solaris kernel, the lack of ownership inherent in semaphore objects inhibits their widespread use. See semaphore(9F) for details.


A user-level synchronization object. All blocking on user-level synchronization objects is handled with SOBJ_USER synchronization objects. User-level synchronization objects include those created with mutex_init(3C), sema_init(3C), rwlock_init(3C), cond_init(3C) and their POSIX equivalents.


A user-level synchronization object that implements priority inheritance. Some user-level synchronization objects that track ownership additionally allow for priority inheritance. For example, mutex objects created with pthread_mutex_init(3C) may be made to inherit priority using pthread_mutexattr_setprotocol(3C).


A shuttle synchronization object. Shuttle objects are used to implement doors. See door_create(3DOOR) for more information. 

The pr_state field is set to one of the values in Table 25–5. The pr_sname field is set to a corresponding character shown in parentheses in the same table.

Table 25–5 pr_state Values


The thread is sleeping. The sched:::sleep probe will fire immediately before a thread's state is transitioned to SSLEEP.


The thread is runnable, but is not currently running. The sched:::enqueue probe will fire immediately before a thread's state is transitioned to SRUN.


The thread is a zombie LWP. 


The thread is stopped, either due to an explicit proc(4) directive or some other stopping mechanism.


The thread is an intermediate state during process creation. 


The thread is running on a CPU. The sched:::on-cpu probe will fire in the context of the SONPROC thread a short time after the thread's state is transitioned to SONPROC.