Probes

The sysinfo provider makes available probes that correspond to the fields in the sys named kernel statistic: a probe provided by sysinfo fires immediately before the corresponding sys value is incremented. The following example shows how to display both the names and the current values of the sys named kernel statistic using the kstat(1M) command.

$ kstat -n sys
module: cpu                             instance: 0
name:   sys                             class:    misc
    bawrite                         123
    bread                           2899
    bwrite                          17995
...

The sysinfo probes are described in Table 23-1.

Table 23-1 sysinfo Probes

`bawrite`	Probe that fires whenever a buffer is about to be asynchronously written out to a device.
`bread`	Probe that fires whenever a buffer is physically read from a device. `bread` fires after the buffer has been requested from the device, but before blocking pending its completion.
`bwrite`	Probe that fires whenever a buffer is about to be written out to a device, whether synchronously or asynchronously.
`idlethread`	Probe that fires whenever a CPU enters the idle loop.
`intrblk`	Probe that fires whenever an interrupt thread blocks.
`inv_swtch`	Probe that fires whenever a running thread is forced to involuntarily give up the CPU.
`lread`	Probe that fires whenever a buffer is logically read from a device.
`lwrite`	Probe that fires whenever a buffer is logically written to a device
`modload`	Probe that fires whenever a kernel module is loaded.
`modunload`	Probe that fires whenever a kernel module is unloaded.
`msg`	Probe that fires whenever a `msgsnd`(2) or `msgrcv`(2) system call is made, but before the message queue operations have been performed.
`mutex_adenters`	Probe that fires whenever an attempt is made to acquire an owned adaptive lock. If this probe fires, one of the `lockstat` provider's `adaptive-block` or `adaptive-spin` probes will also fire. See Chapter 18, `lockstat` Provider for details.
`namei`	Probe that fires whenever a name lookup is attempted in the filesystem.
`nthreads`	Probe that fires whenever a thread is created.
`phread`	Probe that fires whenever a raw I/O read is about to be performed.
`phwrite`	Probe that fires whenever a raw I/O write is about to be performed.
`procovf`	Probe that fires whenever a new process cannot be created because the system is out of process table entries.
`pswitch`	Probe that fires whenever a CPU switches from executing one thread to executing another.
`readch`	Probe that fires after each successful read, but before control is returned to the thread performing the read. A read may occur through the `read`(2), `readv`(2) or `pread`(2) system calls. `arg0` contains the number of bytes that were successfully read.
`rw_rdfails`	Probe that fires whenever an attempt is made to read-lock a readers/writer when the lock is either held by a writer, or desired by a writer. If this probe fires, the `lockstat` provider's `rw-block` probe will also fire. See Chapter 18, `lockstat` Provider for details.
`rw_wrfails`	Probe that fires whenever an attempt is made to write-lock a readers/writer lock when the lock is held either by some number of readers or by another writer. If this probe fires, the `lockstat` provider's `rw-block` probe will also fire. See Chapter 18, `lockstat` Provider for details.
`sema`	Probe that fires whenever a `semop`(2) system call is made, but before any semaphore operations have been performed.
`sysexec`	Probe that fires whenever an `exec`(2) system call is made.
`sysfork`	Probe that fires whenever a `fork`(2) system call is made.
`sysread`	Probe that fires whenever a `read`(2), `readv`(2), or `pread`(2) system call is made.
`sysvfork`	Probe that fires whenever a `vfork`(2) system call is made.
`syswrite`	Probe that fires whenever a `write`(2), `writev`(2), or `pwrite`(2) system call is made.
`trap`	Probe that fires whenever a processor trap occurs. Note that some processors, in particular UltraSPARC variants, handle some light-weight traps through a mechanism that does not cause this probe to fire.
`ufsdirblk`	Probe that fires whenever a directory block is read from the UFS file system. See `ufs`(7FS) for details on UFS.
`ufsiget`	Probe that fires whenever an inode is retrieved. See `ufs`(7FS) for details on UFS.
`ufsinopage`	Probe that fires after an in-core inode without any associated data pages has been made available for reuse. See `ufs`(7FS) for details on UFS.
`ufsipage`	Probe that fires after an in-core inode with associated data pages has been made available for reuse. This probe fires after the associated data pages have been flushed to disk. See `ufs`(7FS) for details on UFS.
`writech`	Probe that fires after each successful write, but before control is returned to the thread performing the write. A write may occur through the `write`(2), `writev`(2) or `pwrite`(2) system calls. `arg0` contains the number of bytes that were successfully written.
`xcalls`	Probe that fires whenever a cross-call is about to be made. A cross-call is the operating system's mechanism for one CPU to request immediate work of another CPU.

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