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Technical Reference: Base Operating System and Extensions , Volume 2
Read the WLM disk I/O
statistics per class or per device
Workload Manager Library (libwlm.a)
#include <sys/types.h>
#include <sys/wlm.h>
int wlm_get_bio_stats ( dev, array, count, class, flags)
dev_t dev;
void *array;
int *count;
char *class;
int flags;
The wlm_get_bio_stats subroutine is used to get the WLM disk IO
statistics. There are two types of statistics available:
- The statistics about disk IO utilization per class and per devices,
returned by wlm_get_bio_stats in wlm_bio_class_info_t
structures,
- The statistics about the disk IO utilization per device, all classes
combined, returned by wlm_get_bio_stats in
wlm_bio_dev_info_t structures.
The type of statistics returned by the function is predicated on the value
of the flags argument. The flags argument,
together with the dev and class arguments, are used to
restrict the scope of the function to a class or a set of classes and/or a
device or a set of devices. If the value passed to the routine in the
count argument is equal to zero (0), wlm_get_bio_stats
does not copy any device statistics (and, in this case, the array
argument can be a NULL pointer but sets this count to the number of elements
in scope for the specific set of parameters. This is a way of finding
out how big an array is needed to get all the information for a given set of
classes and devices.
wlm_get_bio_stats does not require any special privileges and is
accessible to all users. wlm_get_bio_stats fails if WLM is
off.
flags
| Need to be initialized with WLM_VERSION. Optionally,
the following flag values can be or'ed to WLM_VERSION:
- WLM_SUPER_ONLY
- Limits the scope to superclasses only
- WLM_SUB_ONLY
- Limits the scope to subclasses only
- WLM_BIO_CLASS_INFO
- Per class statistics requested
- WLM_BIO_DEV_INFO
- Per device statistics requested
- WLM_BIO_ALL_DEV
- Requests statistics for all devices. When this flag is set, the
value passed in the dev argument is ignored.
- WLM_BIO_ALL_MINOR
- Requests statistics for all devices associated with a given major
number. When this flag is set, only the major number part of the value
passed in the dev argument is used.
- WLM_VERBOSE_MODE
- Shows the system defined subclasses (Default and
Shared)even if they have not been modified by a WLM
administrator.
One of the flags WLM_BIO_CLASS_INFO or
WLM_BIO_DEV_INFO (and only one) must be specified.
WLM_SUPER_ONLY and WLM_SUB_ONLYare mutually
exclusive.
|
dev
| Device identification (major, minor) of a disk device.
- If dev is equal to 0, the statistics for all devices are
returned (even if WLM_BIO_ALL_DEV is not specified in the
flags argument).
- If dev is not equal to 0 and WLM_BIO_ALL_MINOR is
specified in the flags argument, the statistics for all disk
devices with the same major number specified in dev are
returned.
- If dev is not equal to 0 and WLM_BIO_ALL_MINOR is
not specified in the flags argument, only the statistics for the
disk device with the major and minor numbers specified in dev are
returned.
|
array
| Pointer to an array of wlm_bio_class_info_t structures (when
WLM_BIO_CLASS_INFO is specified in the flags argument)
or an array of wlm_bio_dev_info_t structures (when
WLM_BIO_DEV_INFO is specified in the flags
argument). A NULL pointer can be passed together with a
count of 0 to determine how many elements are in scope for the set
of arguments passed.
|
count
| The address of an integer containing the maximum number of elements to be
copied into the array above. If the call to
wlm_get_bio_stats is successful, this integer will contain the
number of elements actually copied. If the initial value is equal to
zero (0), wlm_get_bio_stats sets this value to the number elements
selected by the specified combination of flags and class.
|
class
| A pointer to a character string containing the name of a superclass or
subclass. If class is a pointer to an empty string (""), the
information for all classes are returned. The class
parameter is taken into account only when the flag
WLM_BIO_CLASS_INFO is set.
|
Upon successful completion, a value of 0 is returned and the value pointed
to by count is set to the number of elements copied into the array
of structures pointed to by array. If the
wlm_get_bio_stats subroutine is unsuccessful a non 0 value is
returned.
For a list of the possible error codes returned by the WLM API functions,
see the description of the header file sys/wlm.h.
The wlm.h header file.
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