kstat(9S) manual page
Table of Contents
kstat - kernel statistics structure
#include <sys/types.h>
#include <sys/kstat.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
Solaris DDI specific (Solaris DDI)
Each kernel
statistic (kstat) exported by device drivers consists of a header section
and a data section. The kstat structure is the header portion of the statistic.
A driver receives a pointer to a kstat structure from a successful call
to kstat_create(9F)
. Drivers should never allocate a kstat structure in
any other manner.
After allocation, the driver should perform any further
initialization needed before calling kstat_install(9F)
to actually export
the kstat.
| void | *ks_data; | /* kstat type-specific data */ |
| ulong_t | ks_ndata; | /*
# of type-specific data records */ |
| ulong_t | ks_data_size; | /* total size of kstat
data section */ |
| int | (*ks_update)(struct kstat *, int); |
| void | *ks_private; | /*
arbitrary provider-private data */ |
| void | *ks_lock; | /* protects this kstat’s data
*/ |
The members of the kstat structure available to examine or set by a driver
are as follows:
- ks_data
- points to the data portion of the kstat. Either
allocated by kstat_create(9F)
for the drivers use, or by the driver if
it is using virtual kstats.
- ks_ndata
- is the number of data records in this
kstat. Set by the ks_update(9E)
routine.
- ks_data_size
- is the amount of data
pointed to by ks_data. Set by the ks_update(9E)
routine.
- ks_update
- is a pointer
to a routine which dynamically updates kstats. This is useful for drivers
where the underlying device keeps cheap hardware stats, but extraction
is expensive. Instead of constantly keeping the kstat data section up to
date, the driver can supply a ks_update(9E)
function which updates the
kstat’s data section on demand. To take advantage of this feature, set the
ks_update field before calling kstat_install(9F)
.
- ks_private
- is a private
field for the driver’s use. Often used in ks_update(9E)
.
- ks_lock
- is a pointer
to a mutex that protects this kstat. kstat data sections are optionally
protected by the per-kstat ks_lock. If ks_lock is non-NULL
, kstat clients
(such as /dev/kstat) will acquire this lock for all of their operations
on that kstat. It is up to the kstat provider to decide whether guaranteeing
consistent data to kstat clients is sufficiently important to justify the
locking cost. Note, however, that most statistic updates already occur
under one of the provider’s mutexes, so if the provider sets ks_lock to
point to that mutex, then kstat data locking is free. ks_lock is really
of type (kmutex_t *); it is declared as (void *) in the kstat header so
that users don’t have to be exposed to all of the kernel’s lock-related data
structures.
kstat_create(9F)
Table of Contents
![[Go to CFHT Home Page]](/images/cfht-icon.gif){kind=icon}
Man Pages 
Back to Software Index 
Manpage Top Level