tnf_kernel_probes(4)

NAME

tnf_kernel_probes − TNF kernel probes

DESCRIPTION

The set of probes (trace instrumentation points) available in the standard kernel. The probes log trace data to a kernel trace buffer in Trace Normal Form (TNF). Kernel probes are controlled by prex(1). A snapshot of the kernel trace buffer can be made using tnfxtract(1) and examined using tnfdump(1).

Each probe has a name and is associated with a set of symbolic keys, or categories. These are used to select and control probes from prex(1). A probe that is enabled for tracing generates a TNF record, called an event record. An event record contains two common members and may contain other probe-specific data members.

Common Members

tnf type name	member name
tnf_probe_event	tag
tnf_time_delta	time_delta

tag encodes TNF references to two other records:

tag describes the layout of the event record

schedule identifies the writing thread and also contains a 64-bit base time in nanoseconds.

time_delta a 32-bit time offset from the base time; the sum of the two times is the actual time of the event.

Threads

thread_create

	tnf_kthread_id	tid
	tnf_pid	pid
	tnf_symbol	start_pc

Thread creation event.

tid the thread identifier for the new thread

pid the process identifier for the new thread

start_pc the kernel address of its start routine.

thread_state

	tnf_kthread_id	tid
	tnf_microstate	state

Thread microstate transition events.

tid optional; if it is absent, the event is for the writing thread, otherwise the event is for the specified thread.

state indicates the thread state:

• running in user mode

• running in system mode

• asleep waiting for a user-mode lock

• asleep on a kernel object,

• runnable (waiting for a cpu)

• stopped.

The values of this member are defined in <sys/msacct.h>. Note that to reduce trace output, transitions between the system and user microstates that are induced by system calls are not traced. This information is implicit in the system call entry and exit events.

thread_exit

Thread termination event for writing thread. This probe has no data members other than the common members.

Scheduling

thread_queue

	tnf_kthread_id	tid
	tnf_cpuid	cpuid
	tnf_long	priority
	tnf_ulong	queue_length

Thread scheduling events. These are triggered when a runnable thread is placed on a dispatch queue.

cpuid specifies the cpu to which the queue is attached.

priority the (global) dispatch priority of the thread.

queue_length the current length of the cpu’s dispatch queue.

Blocking

thread_block

	tnf_opaque	reason
	tnf_symbols	stack

Thread blockage event. This probe captures a partial stack backtrace when the current thread blocks.

reason the address of the object on which the thread is blocking.

symbols references a TNF array of kernel addresses representing the PCs on the stack at the time the thread blocks.

System Calls

syscall_start

tnf_sysnum

sysnum

System call entry event.

sysnum the system call number. The writing thread implicitly enters the system microstate with this event.

syscall_end

	tnf_long	rval1
	tnf_long	rval2
	tnf_long	errno

System call exit event.

rval1

rval2 the two return values of the system call

errno the error return.

The writing thread implicitly enters the user microstate with this event.

Page Faults

address_fault

	tnf_opaque	address
	tnf_fault_type	fault_type
	tnf_seg_access	access

Address-space fault event.

address gives the faulting virtual address.

fault_type gives the fault type: invalid page, protection fault, software requested locking or unlocking.

access gives the desired access protection: read, write, execute or create. The values for these two members are defined in <vm/seg_enum.h>.

major_fault

	tnf_opaque	vnode
	tnf_offset	offset

Major page fault event. The faulting page is mapped to the file given by the vnode member, at the given offset into the file. (The faulting virtual address is in the most recent address_fault event for the writing thread.)

anon_private

tnf_opaque

address

Copy-on-write page fault event.

address the virtual address at which the new page is mapped.

anon_zero

tnf_opaque

address

Zero-fill page fault event.

address the virtual address at which the new page is mapped.

page_unmap

	tnf_opaque	vnode
	tnf_offset	offset

Page unmapping event. This probe marks the unmapping of a file system page from the system.

vnode and offset
identify the file and offset of the page being unmapped.

Pageins and Pageouts

pagein

	tnf_opaque	vnode
	tnf_offset	offset
	tnf_size	size

Pagein start event. This event signals the initiation of pagein I/O.

vnode and offset
identify the file and offset to be paged in.

size specifies the number of bytes to be paged in.

pageout

	tnf_opaque	vnode
	tnf_ulong	pages_pageout
	tnf_ulong	pages_freed
	tnf_ulong	pages_reclaimed

Pageout completion event. This event signals the completion of pageout I/O.

vnode identifies the file of the pageout request.

pages_pageout the number of pages written out.

pages_freed the number of pages freed after being written out.

pages_reclaimed the number of pages reclaimed after being written out.

Page Daemon (Page Stealer)

pageout_scan_start

	tnf_ulong	pages_free
	tnf_ulong	pages_needed

Page daemon scan start event. This event signals the beginning of one iteration of the page daemon.

pages_free the number of free pages in the system.

pages_needed the number of pages desired free.

pageout_scan_end

	tnf_ulong	pages_free
	tnf_ulong	pages_scanned

Page daemon scan end event. This event signals the end of one iteration of the page daemon.

pages_free the number of free pages in the system.

pages_scanned the number of pages examined by the page daemon. (Potentially more pages will be freed when any queued pageout requests complete.)

Swapper

swapout_process

	tnf_pid	pid
	tnf_ulong	page_count

Address space swapout event. This event marks the swapping out of a process address space.

pid identifies the process.

page_count reports the number of pages either freed or queued for pageout.

swapout_lwp

	tnf_pid	pid
	tnf_lwpid	lwpid
	tnf_kthread_id	tid
	tnf_ulong	page_count

Light-weight process swapout event. This event marks the swapping out of an LWP and its stack.

pid the LWP’s process identifier

lwpid the LWP identifier

tid member the LWP’s kernel thread identifier.

page_count the number of pages swapped out.

swapin_lwp

	tnf_pid	pid
	tnf_lwpid	lwpid
	tnf_kthread_id	tid
	tnf_ulong	page_count

Light-weight process swapin event. This event marks the swapping in of an LWP and its stack.

pid the LWP’s process identifier

lwpid the LWP identifier

tid the LWP’s kernel thread identifier.

page_count the number of pages swapped in.

Local I/O

strategy

	tnf_device	device
	tnf_diskaddr	block
	tnf_size	size
	tnf_opaque	buf
	tnf_bioflags	flags

Block I/O strategy event. This event marks a call to the strategy(9E) routine of a block device driver.

device contains the major and minor numbers of the device.

block the logical block number to be accessed on the device.

size the size of the I/O request.

buf the kernel address of the buf(9S) structure associated with the transfer.

flags the buf(9S) flags associated with the transfer.

biodone

	tnf_device	device
	tnf_diskaddr	block
	tnf_opaque	buf

Buffered I/O completion event. This event marks calls to the biodone(9F) routine.

device contains the major and minor numbers of the device.

block the logical block number accessed on the device.

buf the kernel address of the buf(9S) structure associated with the transfer.

physio_start

	tnf_device	device
	tnf_offset	offset
	tnf_size	size
	tnf_bioflags	rw

Raw I/O start event. This event marks entry into the physio(9F) routine which performs unbuffered I/O.

device contains the major and minor numbers of the device of the transfer.

offset the logical offset on the device for the transfer.

size the number of bytes to be transferred.

rw the direction of the transfer: read or write (see buf(9S)).

physio_end

tnf_device

device

Raw I/O end event. This event marks exit from the physio(9F) routine.

device the major and minor numbers of the device of the transfer.

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